Wednesday, July 30, 2014

Downhills

A short post.  Niholas, with a confident rider and in the right situations, are surprisingly easy to drive very quickly downhill.  Well in this case "very" means perhaps 35-40km/hr, to speeds where the wind roars in the ears, and guys in stretch pants riding racing bikes can't pass a coasting trike without pedaling.  It basically gets easier the more weight is in the box, and the lower and more behind-the-front-axle that weight is.  A loaded Nihola goes down a hill like a cannon ball.  A 20kg kid or two really stabilizes things, and the trike runs smoothly through the corners and pavement imperfections, but an empty Nihola with well-pumped tires is a bit jittery.  I've pedaled (sprinted) to about 35km/hr (based on a GPS track) but generally at those speeds its best to concentrate on smooth driving, and plan well ahead in case it might be necessary to stop.  Definitely a good idea to remember that stopping takes a while.

Gravel downhills work great too, so long as the bumps are not large enough to start throwing people and trikes around.  The tires and frame can smooth out a half-decent gravel road very well with a kid or two in the box, and it just seems to get smoother with speed... just avoid washboard and holes.

Niholas are also great fun on downhills when there are slippery corners.  In this past winter I was doing three-wheel slides in the snow, and in the summer I have a time or two had the chance to push it to the limit on dirty pavement.  I can't recall going nuts on gravel but I think it could be fun too.  I've noticed that in the summer, when riding fast and using the back brake hard, it tends to have abrupt consequences on directional stability.  Its perhaps more fun to squeeze 100% out of the front brakes and corner until the inside tire starts sliding.

Oh, and my kids love speedbumps.

Sunday, July 20, 2014

Brakes

An unusual Nihola that was pictured on the French Nihola site.
The picture above shows a special Nihola.  It has disc brakes in front.  And it also is designed to carry pallets, which is a bit unusual.  But about those disc brakes.  Disc brakes are unfortunately not an option that be ordered on a Nihola by anyone who isn't willing to pay for custom fabrication.  Its easy to see why the Nihola company selected mild-mannered and inexpensive drum brakes up front when virtually all Niholas are sold in Copenhagen, where such brakes are sufficient, even optimal.  Notably the big competitor Christania Cycles does offer disc brakes, as does Bullitt.  There is certainly no need for the strength of disc brakes in Copenhagen, but they look good and who knows, maybe the maintenance isn't too bad.  Its a bit unfortunate, in my opinion, that the Nihola company doesn't offer to take people's money in trade for a disc brake option, because what is decorative in Copenhagen could be practical in Oslo.
Its hard to photograph a hill, but this was a good one.
Climbing out of a valley on route from H√łnefoss to Oslo.

So I should talk about how braking works on a Nihola.  The rear is either a coaster brake (foot brake) or a v-brake, but could in theory also be a different type of hub-mounted drum such as a roller brake (grease-filled drum from Shimano).  I estimate that there is zero possibility of a disc in the rear, the lack of mounts being a prominent problem, but also the shape of the frame appears incompatible, which is a shame because all the most interesting gear hubs are available with disc mounts.  Discs aren't perfect, but I'd take a disc over a rim brake on the rear wheel of a cargo bike.

Now, the rear brake doesn't necessarily need to be strong.  Ideally it is easy to modulate, to use whatever traction is available.  Foot brakes are not known for being strong, but are more than strong enough to skid the back tire on clean pavement (presuming no weight on the rear rack).  The reason that strength is not a problem is because of the significant forward weight transfer under hard braking, especially when weight is concentrated in the box, and also especially on downhill slopes.  This all is to say, the rear brake is generally of little use for quick stops.  This effect is more significant on a Nihola than a regular bike.

Regrettably, the brakes in front are also of little use for quick stops.  They are always 7cm Sturmey-Archer drums, a type of non-greased drum with a replaceable brake shoe.  One single-pull 4-finger lever pulls to a splitter which seeks to distribute force evenly between the left and right, or perhaps it just seeks to keep the cables to each side the same length.  There is, anyway, a splitter which has the potential to allow more cable to be pulled on one side than the other (this pulling is not smooth in my experience) and which has the potential to keep the cables to the front brakes roughly the same length.  It seems to me that the observable strength of the front brakes is usually mismatched if any particular strength can be observed at all, so the splitter is not an effective way to balance braking power.

The brakes, freshly adjusted, are strong enough that on flat ground, with an empty Nihola, I need to brace myself against the handlebar when doing a 100% stop.  Some exertion is required, but certainly no danger of going over the bars unless I could somehow brake without having my hands on them, and certainly no possibility of lifting the back tire off the ground.  Gradual and smooth is the idea.  This is mostly fine at reasonable speeds and on flat ground, but hills are more problematic.  By about 10% slope, I get the impression that the brakes are mostly there to prevent speed from increasing.  Stopping requires planning ahead.  The steeper the slope, the more planning ahead is required.  The brakes are sufficient to hold the trike in place to over 25%, which I suppose is evidence that stopping is possible at such a slope, but this will require the rear brake to be used without much skidding.  A skidding rear tire is not being very helpful.

Skidding the front tires is not easy to do.  The easiest way is to brake hard when turning sharp corners at speed.  Often, because the strength of the front brakes is likely imbalanced, this is possible turning one way and not the other.  About the only other time I've managed is when one brake arm is seized up, apparently causing the other brake to gain strength, which can skid a tire on gravel.  Load in the box makes skidding a lot harder.

The view on a day tour. 
Lots of people will say drums are a low-maintenance cycle brake, but I've spent plenty of time screwing around with the drums on my two Niholas since moving to Oslo.  Understandably, stopping 150kg of trike, cargo and rider on some of these hills can be demanding.  The brakes can easily get too hot to touch.  It rains, it snows, salt and/or other chemicals are sprayed around, there is sand and gravel, mud... sometimes I get plants caught up around the brakes, and often enough they stand outside in the weather.  Its true that little cleaning is required.  There is no particular seal on the brakes, just a design which makes it somewhat non-obvious for water to flow in.  Mostly that appears to get the job done, but if moisture enters, the brakes can be weaker while wet, and can rust a bit on the braking surface.  The rust wears off but appears to contribute to lumpy and/or squeaky braking.

Squeaking from the front brakes can be a major irritant, but can also be entirely nonexistant.  Its difficult for me to figure out what causes the squeaking or how it can be fixed.  Simply using the brakes more will only silence the squeaks until the brakes cool down again, and cleaning seems to have only a short-term effect, but sometimes the passage of time (or the change of weather) seems to change the squeaking situation.  I got though months of snow and melting this winter with perfectly quiet and predictable brake behavior for no reason I can see, although there was some squeaking a week or two after I tightened up front brake cables in the summer.  Squeaking is often associated with strong braking performance, but not always.  There is a possibility that getting the brakes very hot encourages squeaking the next time (next day) they are used.  Mysterious.

The center adjuster with its rubber cover pulled up.
So, maintenance.  The brake arms need to be lubed (drip or spray some oil at the base) or they will start to seize up, which can have interesting effects because it may start causing all cable movement to be "routed" to the easier-to-operate brake, in a crude way.  Definitely oil those arms.  Brake dust might need to be cleaned out from time to time.  Cable stretch and/or brake wear require the brake cable to be tightened, and this is the most interesting bit of service to perform.  For small adjustments, there is an adjuster in the center, above the splitter.  For big adjustments, I have found that the center adjuster should be slackened, the cable fastening bolts on each brake arm should be loosened, both brake arms should be fully engaged (full brake), and the fastening bolts should be tightened again.  So the brake arms are held some distance towards engagement permanently.  Surprisingly, this does not result in dragging brakes, merely a firm brake handle and optimized brake strength.  A brake handle which pulls up close to the handlebars indicates that braking strength could be improved.  In other words, it seems that more strength is delivered when the brakes engage early in the travel of the brake lever, even in the case of a brake lever that pulls a long way but does not touch the hand grip.  I don't know why that is, but the difference can be very noticeable.

The splitter, just a round thing that the brake cable is looped over.  Note center cable at the top.

An exposed brake, with the brake arm visible to the right.
A wrench being used to hold the brake arm fully engaged while the cable on the other side is fastened.
The drums behave strangely when asked to deliver 100%.  The strength seems to reach a certain level fairly easily, and then does not improve further, regardless of the force applied to the brake lever.  I expect that the cable liner running between the lever and the spitter has started to compress at that point.  Fitting a more compression-resistant section of cable liner could improve braking strength.  I've also been tempted to set up the left and right brakes with separate levers, using a foot brake for the rear.  This would have the potential to be a lot of fun on downhill corners.

I've noticed that Sturmey Archer makes a 9cm drum that almost fits on a Nihola, as far as I can tell from photos.  Certainly the Nihola company could make it fit with a small alteration to the piece of metal that is tasked with anchoring the top of the brake's back plate and the fender.  I imagine the 9cm drum would be stronger for the same cable tension, longer lasting, slower to heat, and make for a stiffer wheel (the front wheels have a hard life).

Anyway the brakes on a Nihola are probably the weakest link for 'ambitious' owners.

Gear hub madness

Today I came across a good description of how the new SRAM G8 hub works, and I worked through the ratios in a spreadsheet. Its a strange hub and it took me a while to figure out what was going on, even when someone had already attempted to explain it. This got me thinking about another difficult nut to crack, the Alfine 11.

As far as I can determine, no one has done a teardown of an Alfine 11, counted the teeth, or posted any particular information about how its ratios are created.  In the past, I've thought it was quite similar in design to a Nexus 7, but now I've changed my mind.  However before that, lets go on a tour of gear ratios in hubs.

Gear hubs are made up of planetary gear sets: http://en.wikipedia.org/wiki/Epicyclic_gearing

Generic three speed:

The most basic hubs have one gear set, giving three speeds.  In the middle there is direct drive, then one ratio increased and one ratio decreased (the inverse of the increased ratio).

gear 1 2 3
ratio 0,750 1,000 1,333
ratio change 33 % 33 %
name 1/A - A
calculated ratio 0,750 1,000 1,333

SRAM P5:

This was extended to make 5 speeds such as the SRAM P5 by placing two gear sets into one module, so that one of two ratios could be used at a time, either up or down.

gear 1 2 3 4 5
ratio 0,633 0,781 1,000 1,281 1,579
ratio change 23 % 28 % 28 % 23 %
name 1/A 1/B - B A
calculated ratio 0,633 0,781 1,000 1,281 1,579

SRAM S7:

This also worked for 7 speeds, such as the SRAM S7.

gear 1 2 3 4 5 6 7
ratio 0,574 0,677 0,809 1,000 1,236 1,476 1,742
ratio change 18 % 19 % 24 % 24 % 19 % 18 %
name 1/A 1/B 1/C - C B A
calculated ratio 0,574 0,678 0,809 1,000 1,236 1,476 1,742

SRAM i-Motion 9:

It even worked for a 9 speed, the i-Motion 9.  This hub was basically a failure on the market, apparently because it was too heavy, rough running, expensive, and poorly sealed against weather.  However it was apparently well constructed, and it did achieve 9 tight and evenly-spaced ratios while using only one planetary gear at a time, potentially giving high efficiency.  I think its a shame it didn't make it.

gear 1 2 3 4 5 6 7 8 9
ratio 0,542 0,621 0,727 0,853 1,000 1,172 1,375 1,611 1,844
ratio change 15 % 17 % 17 % 17 % 17 % 17 % 17 % 14 %
name 1/A 1/B 1/C 1/D - D C B A
calculated ratio 0,542 0,621 0,727 0,853 1,000 1,172 1,375 1,611 1,844

Shimano Nexus 4:

But there are other fun things that might be done.  Consider a Nexus 4, which made four ratios from a set of three planetary gears, by only increasing ratios.  Leaving out the ability to decrease ratios simplified the hub.  This simplification, where each planetary gear is only used to either increase or decrease ratio but not both, is a major theme of all recent hubs.  There i-Motion 9 above might well have needed only 4 planetary gears to get 9 beautiful-looking ratios, but those 4 gears were too complicated.

gear 1 2 3 4
ratio 1,000 1,244 1,500 1,843
ratio change 24 % 21 % 23 %
name - A B C
calculated ratio 1,000 1,244 1,500 1,843

Shimano Nexus 5:

But all these hubs have fairly large steps between the gears.  Especially the gap between direct drive and the first ratio up or down was problematic.  While i-Motion 9 got this down to 17%, it was apparently unpleasant.  Even the 22% gap on Nexus 8 leads to some gear whine.  So Shimano got busy with dual-stage compounding its planetary gear sets.  Below is the Nexus 5, which used three planetary gears in two sets, and has no direct drive ratio at all, but is very smooth in my experience.

gear 1 2 3 4 5
ratio 0,750 1,001 1,159 1,335 1,545
ratio change 33 % 16 % 15 % 16 %
name 1/A B/A C/A B C
calculated ratio 0,750 1,001 1,159 1,335 1,545

Shimano Nexus 7:

The Nexus 7 is similar, but with four planetary gears arranged in two sets.  I've used two of these extensively and never been satisfied with either their smoothness or efficiency, but they seem to sell in vast quantities in Denmark.

gear 1 2 3 4 5 6 7
ratio 0,632 0,741 0,843 0,989 1,145 1,335 1,545
ratio change 17 % 14 % 17 % 16 % 17 % 16 %
name 1/A 1/B C/A C/B D/B C D
calculated ratio 0,632 0,741 0,844 0,989 1,145 1,335 1,545

Shimano Nexus 8 / Shimano Alfine 8:

But thats not the only way to do multi-stage compounding.  The Nexus/Alfine 8 is a lot like the old Nexus 4 with a new planetary gear enabling the four original ratios to be used twice.  This leaves a direct drive gear in place which is good, but creates an odd situation where the least efficient gear (4) is right next to the most efficient (5), and switching between the "high" and "low" gears can be problematic.  Still, this seems to be a robust design.

gear 1 2 3 4 5 6 7 8
ratio 0,527 0,644 0,748 0,851 1,000 1,223 1,419 1,615
ratio change 22 % 16 % 14 % 18 % 22 % 16 % 14 %
name 1/A B/A C/A D/A - B C D
calculated ratio 0,527 0,645 0,748 0,851 1,000 1,223 1,419 1,615

Rohloff:

And then there is the monsterous 14 speed Rohloff, that uses 5 planetary gears in three sets.  Gears 3 and 5 actually use triple-stage compounding, which is hard to notice in my experience.  In some ways this combines concepts which are found on both Nexus 7 and Nexus 8, sort of a combination of those designs.

gear 1 2 3 4 5 6 7 8 9 10 11 12 13 14
ratio 0,279 0,316 0,360 0,409 0,464 0,528 0,600 0,682 0,774 0,881 1,000 1,135 1,292 1,467
ratio change 13 % 14 % 14 % 13 % 14 % 14 % 14 % 13 % 14 % 14 % 14 % 14 % 14 %
name 1/B * 1/A 1/C * 1/A D/B * 1/A 1/A E/C * 1/A D/A E/A 1/B 1/C D/B - E/C D E
calculated ratio 0,279 0,317 0,360 0,409 0,464 0,528 0,600 0,682 0,774 0,881 1,000 1,135 1,292 1,467

SRAM G8:

Here is the SRAM G8 in all its confusing glory.  Five planetary gears in two sets, sort of arranged like a backwards Nexus/Alfine 8.  No direct drive, and 6 of the 8 ratios are two-stage compounded.  http://sheldonbrown.com/sram-g8.html

gear 1 2 3 4 5 6 7 8
ratio 0,609 0,710 0,803 0,903 1,054 1,204 1,355 1,581
ratio change 17 % 13 % 12 % 17 % 14 % 13 % 17 %
name 1/B 1/C E/A E/B E/C D/A D/B D/C 1/A D E
calculated ratio 0,609 0,710 0,803 0,904 1,054 1,204 1,356 1,580 0,5411 2,2258 1,4839

Shimano Alfine 11:

Then finally we get to the Alfine 11.  I spent some time on this.  There are lots of ways to make a good approximation of the published ratios, but the way I am most satisfied with uses four planetary gears arranged in three sets.  The main difference between this and Nexus/Alfine 8 is that one gear (number 7) is able to combine with gears 8 and 9 to create ratios 10 and 11.  Then all those resulting 5 ratios are re-used in positions 2-6.  This very nicely explains the 29.2% gap between gears 1 and 2... its same ratio as gear 7 has.  This also has no planetary gears which are used to both increase and decrease ratios, which appears to be very much out of style, it explains the alternating 13% and 14% ratio changes, and it explains how the 11 speed is able to match the weight of the 8 speed.  Essentially, the same number and strength of gears needed to be used.

There is no direct drive ratio, which is instead replaced by a triple-compound approximation, I imagine to achieve mechanical simplicity.  The only difference between 2-6 and 7-11 is whether or not the "low range gear" is active.

gear 1 2 3 4 5 6 7 8 9 10 11
ratio 0,527 0,681 0,770 0,878 0,995 1,134 1,292 1,462 1,667 1,888 2,153
ratio change 29,2 % 13,1 % 14,0 % 13,3 % 14,0 % 13,9 % 13,2 % 14,0 % 13,3 % 14,0 %
name 1/A B/A C/A D/A (B*C)/A (B*D)/A B C D B*C B*D
calculated ratio 0,527 0,681 0,770 0,879 0,995 1,135 1,292 1,462 1,667 1,889 2,154

Further reading, here is the grand daddy of complicated bike gear hubs: http://sheldonbrown.com/elanratios.html

Friday, February 28, 2014

Nasty slush

Oslo just hasn't been a proper winter city this year.  After three weeks frozen, its been going back and forth between snow and rain.  Quite a mess on the way to the daycare, but the conditions were nearly perfect during the commute from the daycare to work.  On most days I chose to use the Nihola with less-impressive gearing and the Schwalbe Snow Stud, to benefit the commute part of the daily journey.

Harmless looking, but difficult.  That rut took some effort, but the hill was climbed.
Slope less than 10%, one kid, perhaps 6kg on the rear.
This was especially nasty, hard to drive on even when level, and it packed into the tread.
Spinning solved nothing here.  Having two kids in the box didn't make it easier.
It turns out that really dense snow, stuff which is transitioning into slush and ice via rain, is really a challenge on a hill.  It drags on the tires, and digging might never reach down to anything better.  It seems that bikes have an advantage here due to better weight distribution and more tire per unit of mass.

Parking lot slush.  I should have taken a picture of the ice that followed.
On level ground, slushy snowy crap can be much deeper and rutted without causing too much trouble.  But remember to rock the trike to "push" past the worst parts.

Looks like snow on top, but it transitions to dense slush.
It doesn't take a lot of dense snow underlain by slush and ice to cause a problem on a climb.  The stuff I encountered was really heavy, so just getting the tires through it was a challenge, but if the rear tire dug much it would just come to some sort of dense semi-slush ice.  On level ground it went well enough.

My son eagerly does a bit of cleanup.  This gate is kind of irritating in difficult conditions.
Slope is as much as 15% through here.
Picking up my son after a daytime snow flurry.  Clean snow isn't a problem.
This period has nicely illustrated to me that I am dependent on someone to do at least a halfassed job of snowplowing on the steeper sections of the climb to my son's daycare.

Friday, February 21, 2014

Nexus 8 SG-8C20

When I broke the SRAM P5 that came with our blue Nihola, we spent considerable time trying to find the right replacement.  It would have been a Nuvinci N360 with a roller brake, except the shop in England selling N360's wasn't really interested in ordering one with a roller brake mount, and bike shop employees in Denmark seemed to have little time for "strange" hub gears.  Basically people were not interested in being paid to do anything they didn't normally do; perhaps the margins were too small for them to care.

The Shimano Nexus 8 with foot brake would be another good option, except in Denmark (and some other countries) it was only possible to order the old SG-8C20 version.  It seemed that Shimano refused to sell the SG-8C31 until the old model was sold out (on a per-country basis), and no one could order one for me, nor could I find any for sale online.

I also considered the SG-8R36 with a roller brake, but it was more expensive and we wanted to stick with a coaster brake (foot brake) unless we had a really good reason to change.

So we ordered the old model, the SG-8C20.  It had probably been sitting on a warehouse shelf for years.  I installed it myself.  Right away I had some issues because the "cassette joint" wanted to occupy a bit of space which the chainstay was using.  I installed some extra washers and bent the cassette joint a little to get the shifting in order, but the whole thing was always a pain to fiddle with.

The hub itself was functional, but made me nervous that it was headed for premature death.  From day #1 it made various clicks and had various shifting issues between gears 4 & 5.  Gear 5 (direct drive) seemed like it might slip at any time (but it never actually slipped, except after shifting from 4th).  Adjustment of the shifter could address the various issues but always at a cost somewhere else.  At some point, the clicking and humming alone was enough for me to know what gear my wife was pedaling in, if I rode along behind her.  Still, it was working.

Happily it seems there are ways to address these problems.

The Nihola company had started using Nexus 8 hubs (I presume SG-8R31), so when visiting Copenhagen I checked with them to see how they handled the cassette joint.  Turns out they had some different non-turn washers that I didn't realize existed: 5L and 5R.  They sold me a set of them for a reasonable cost, and one source of irritation dissappeared.


On my next visit to Denmark I took the Nexus 8 into Byman Cykler and had them put some new grease in it.  Now this was the magic the hub needed.  Most of the noises and shift problems vanished and haven't come back (in over 4 months).  So, moral of the story: hubs like fresh grease.

There is one lingering irritation with this hub, however.  It works its axle nuts loose over time, and then pulls itself crooked in the frame.  I guess I'm putting too much torque on it.  Always carry a 15mm wrench!

So now I can make a bit of a verdict on the Nexus 8 with coaster brake as a hub for a Nihola.  Its pretty good.  A bit rough in 3rd and especially 4th gear, in fact its generally a rough hub.  Buts its strong: ours is set up with a 24t sprocket on the hub and 38t on the crank, well beyond any ratio any hub company endorses, and I've put my entire weight on it countless times, plus added arm strength.  I've gotten small blisters from pulling on the handles to force the pedals around.  (I do these terrible things in 1st gear exclusively, which is probably the strongest gear available.)

The Nexus 8 is a strange hub.  Its not symmetric (i.e. the top ratios are not mirror images of the bottom ratios) and the least efficient gears are in the middle of the range (3 & 4) rather than the ends.  However this works out well enough on a Nihola.  For any real hill, I just drop to 1st gear and pedal.  On any reasonably flat ground, I can stick to gears 5-8, which are mostly pleasant.  I never make any strenuous effort in 3rd or 4th gears.

The foot brake is strong enough to slide the rear tire at will, though Oslo hills might cook the hub.  More than once I have been unable to touch the hub's shell after a good downhill.  After that happened a few times, I decided to have a V-brake installed in addition to the foot brake, so now that Nihola has two rear brakes.  Overall I am very pleased with the foot brake.  I'm convinced foot brakes are the best rear brakes for Niholas, except possibly in deep snow, ice, or mud.

But is the Nexus 8 a worthy upgrade over a SRAM P5?  For any moderately serious cyclist, I would say yes.  The ratios are closer, which makes it easier to go fast without knee injuries.  The lowest ratio is good and low.  The hub itself is stronger.  It shifts easier.  Its easier to handle a freezing shift cable.  There is no "clickbox" sticking out in the way of pannier bags.  On the other hand, the P5 is a lot smoother in operation, its likely a bit more efficient, and it doesn't take tools to disconnect its shift cable.

Anyway, Nexus 8 is a good Nihola hub.

Thursday, February 20, 2014

The right winter tire

So we have two Niholas.  They've got different gear hubs and winter tires on them, and I swap back and forth as appropriate.  (We basically only take out both trikes at the same time in the summer.)  Since I can jump back and forth, I've got rather more insight into winter tires on Niholas than most.  Allow me to share.

The fancy trike has a Nokian/Suomi Extreme 294 (26x2.1), and the basic one has a Schwalbe Snow Stud (26x1.9).  While both are studded winter tires, the tires are in different categories.  Which is to say, they can be compared, but the differences outweigh the similarities.  The Extreme has way more studs and has more aggressive tread, which pays off on climbs, and on pavement it sounds like a wheel covered in velcro (especially at low pressures).  The Snow Stud is mild mannered on pavement, making hardly any noise of note, wasting less energy, and doubtless lasting longer, while also being a lot cheaper.  Of course it doesn't climb as well.

And to be clear, the Nokian/Suomi Extreme does climb.  It digs and it scratches; pure ice can possibly be climbed up to a 15% slope with something like 20kg in front 10kg in back, and low pressure.  Softer stuff can be climbed beyond that, however this can require patience, low gearing, and stamina.  The Snow Stud gives and spins up much sooner in almost any snowy, slushy or icy surface.  The worst surface I have experienced for the Snow Stud is one that is icy and slightly lumpy, it just completely defeats the tire.

So here is the difficult part about transporting children as part of a cycle commute in an Oslo winter: each tire is sub-optimal, one could say annoying, when its out of its element.  I haul a kid up a fairly steep and marginally-maintained hill on my way to work, and I also go the rest of the way into the office with less load, on better paths, on the same Nihola.  The tire that can conquer the hill (the Extreme) proceeds to sap my energy and destroy itself on km's of pavement.  The tire (Snow Stud) that is pleasant on the pavement can be difficult to scale the slopes with, in many conditions.  Happily, rear tire inflation can be adjusted to significantly widen the range of situations a given tire can perform acceptably.  Airing up and down is kind of annoying, but its a lot less work than cycling km's with an inefficient tire.  (So: want traction?  Air down.)

For a more normal Nihola usage scenario, which would be a relatively short tour of schools, stores and public transportation, either tire would vastly outperform a standard slick summer tire (in snow or on ice).  Also, with some basic steps like airing down and carrying some kilos on the rear rack, even the Snow Stud will likely provide more traction that the standard gearing of a Nihola can require.  (With the exception of smooth ice.)

A few more nuggets.  Its pretty easy to lock up the rear tire of a Nihola while going down hill on ice.  If not addressed, this can easily lead to the trike not pointing in the same direction it is moving, which is not necessarily cause for alarm, but should probably be corrected.  A rear tire with more studs will make sliding harder and recovery easier.  (I would advise using front and rear brakes on icy hills.)

I have purchased a pair of studded front tires (20x1.6 Schwalbe Marathon Winter), but not installed them.  The regular Schwalbe Marathon Plus tires work pretty well on some pretty slippery stuff, and unlike on a bike, sliding the front tires is not necessarily cause for alarm.  Studs would probably help, but also that adds rolling resistance and noise.  I have decided that the conditions are not currently bad enough to bother swapping the tires.

I would like to try a Schwalbe 26x2.0 Marathon Winter in back.  Looks like a great choice for ice, or even pavement, but its harder to say if it can dig well enough in snow.  One of the problems I've had with the Snow Stud is that it won't dig sufficiently in some types of dense slushy snow.  Sheets of ice may or may not be a primary concern, and the Snow Stud is priced fairly low, so it could be that the humble Snow Stud remains the best trike tire for reasonably flat places with reasonably mild winters.

Update a month later:

Still running the Snow Stud, and its pretty harmless on pavement.  Really not a bad tire for insecure weather.

A Schwalbe Snow Stud is happy even with no snow in sight.

Monday, February 3, 2014

The Nihola vs The Snowy Hill

My son is always ready with the snow shovel.
After a snowless holiday season, Oslo finally reached freezing and stayed there between the 11th of January and the 2nd of February, which was three full working weeks.  Strangely enough, snow fell almost every day, ranging from dust to 10cm/4in.

About when this was all starting, I actually went out with a 60cm/2ft level and tape measure, and made a few measurements of the slope that I need to haul my son up, to reach his daycare.  Of course I didn't want to spend too much time looking ridiculous measuring the public path, so I only measured the most interesting spots.  To jump to the numbers, I can now say that I have definitely climbed slopes over 25% with two kids in the box (lets say 50kg of cargo total) on my 15 gear-inch Nihola.  I can also confidently say that a 15% slope is doable with the same load on my 21 gear-inch Nihola (with a Shimano Nexus 8 hub, nothing exotic).  So thats good to keep in mind.  Niholas can do hills.

The more interesting question to a year-round utility cyclist might be how steep of a slope can be managed when its covered in snow.  I've been testing this the past three weeks, but first a little about the hills I've been climbing.  On the way to the daycare, there is in fact a small bit of 25% slope, rising suddenly after a tunnel under a road.  This flattens to nothing in 40m or so, but its a definite problem spot.  After some modest climbing, a 200m stretch that is up to 10% slope starts, then a stretch of 70m at 12% slope, with a measured max of 15%.  Overall > 50m in < 600m with an average slope of 8-9%.  On the opposite side of that hill, without children, I climb/descend 175m in 3km with slopes up to around 15%, and once in this period I also took a long way home, which ended up being un-plowed for 2km averaging 3% slope.  Now none of this is epic on the scale of hills where snow accumulates, but its plenty hard enough, and since I don't see a lot of people doing it, I might as well share what I have observed.  Perhaps people think its harder than it is.

First observation: I can pedal my Nihola some places and conditions where mountain bikes carrying no particular cargo can't be ridden.  I shouldn't be too proud of myself; sometimes it might be faster to just pick up a bike and walk, than grind through the snow on a trike.  But anyway, if a person is intent on bringing their trike with them, it can be done, and it doesn't involve falling over.

This unstable snow caused a lot of trouble for bikers.
The dark mark is where someone had to fight to remain upright.
Second observation: Light fluffy snow on relatively flat ground is not a problem, given appropriate preparation of the Nihola (rear tire type and inflation, weight in back).  If the snow gets deep enough so that the steering linkages or cargo box start dragging, then forward progress becomes markedly more difficult (depending on how heavy the snow is).  The box bottom is about 15cm/6in off the ground, the lowest steering components are around 11cm/4in, and the pedals go down to around 8cm/3in.

This amount of new snow was no particular problem, even with a shifting foundation underneath.
Further observations: A 25% snow-covered slope is in reach if the conditions are right.  For example, on hard-packed snow, when the temperature was -15C/5F, starting from being almost stopped at the bottom, on a Nihola with around 23kg of stuff in front, 10kg of stuff on the rear rack, 21 gear-inches and a Schwable Snow Stud for traction, I could manage.  You could say that the snow conditions were favorable, providing a firm surface for the tire the bite in.  The relatively sparse studs on that tire were likely of little use in these conditions.

The condition of the road surface is of paramount importance.  On the same section the following day, I had a lot of trouble with the other Nihola.  In that case, the snow was fresh (less than an inch), the temperature was more like -5C/25F, I had closer to 37kg in front, 10kg in back, a more impressive Nokia Extreme (26x2.1) rear tire, and 15 gear-inches to work with.  I had to make multiple attempts at the climb, and only succeeded on the less-steep side of the path and with significant tire slippage.  As the days passed, I continued to climb that nasty spot through various forms of snow, and generally higher temperatures, up to icy melting conditions this morning.  In looser snow, this often meant spinning and digging, with very slow progress and sometimes with rolling backwards to use the excavated trench to build a spot of inertia.  This morning with maybe 17kg in front and 6kg in back (I weighed my bag to see), on wet soft ice, I needed a run at it to clear the steepest parts and could make a little progress from a standstill somewhere over (estimated) 15% slope.  I was carting both kids up the hill, and the older one had to walk there.  Three-wheel balance allowed me to thoroughly confirm that there was no way I'd make it with both kids; usually after a run I was sliding backwards with all three wheels locked up.

Here, the rear tire has scraped up snow shavings from a hard-packed surface.
Here we have dug a trench in semi-packed snow.
Heavy load in front, not much on the rack.
With 2-3 inches of unpacked snow on top of packed snow, around -8C/18F, I had to roll backwards a few times on the 20-25% slope.  Its important to be mindful to push rider weight as far backwards as possible.  The 15% slope areas were difficult but steady, lots more pedal turning than actual forward progress.  I set rear tire inflation quite low, which might have helped.  I doubt I could have it without the 15 gear-inches, but rolling the pedals backwards was unnecessary.

I met various forms of snow in these three weeks, from unpacked to hard packed, and with lots of foot-trodden mushy middle ground.  Obviously hard packed is preferable, but when that was not available, I was not able to determine if it was better to drive where people have made a mess, or where the snow was undisturbed.  Lots of slow work in both.

On soft ice, the advantage of 15 gear-inches is reduced compared to something more like 20 gear-inches, because it was necessary to be very careful with the torque, to maintain traction.  On the other hand, having really low gears allows comfortable crawling while waiting for all the kids sliding down the icy hill to get out of the way.  Its best to keep moving, rather than stopping.  Rolling the pedals backwards was possibly essential in really delicate situations, to avoid breaking traction and starting a backwards slide.

I suspect that hauling kids around on hills in the winter is not an activity that is about to go mainstream.

The snow is melting away, and messy.

Thursday, January 23, 2014

Ray's theory of hills



I have this idea, lets call it Ray's Theory of Hills.  My thought is that once balance is taken out of the equation, and assuming there is sufficient traction, the steepness of the hill that can be climbed is inversely proportional to the gear ratio expressed as gear-inches or meters development, and also inversely proportional to the total weight to be propelled up the hill, including trike and riders.  (This is basically a statement about torque and not horsepower.  We're not talking about racing up hills.  The claim is that your own weight, converted to torque, must be greater than the weight of the cycle and everything in/on it.)

So, you want to take a trike up a hill that is 50% steeper?  Loose 33% of the mass, or lower your gear-inches by 33%.  Or, want to carry 50% more junk?  Lower your gear-inches by 33%, or slopes by 33%.

What does 33% of the mass of a loaded trike add up to, anyway?  So lets say 35kg of Nihola, 75kg of driver, 40kg of kids and 15kg of stuff for a total of 165kg, of which 33% is 55kg.  So by removing all kids and stuff, the same trike and driver could theoretically climb a hill that is 50% steeper (so a 15% slope instead of 10%).  Or put another way, adding the kids and stuff reduces the maximum slope by 33% (so a 10% slope instead of 15%).

Or here's a fun one.  How about removing 10kg from the steel trike by making it an aluminum bike (i.e. swap the Nihola for a Bullitt).  Using the same cargo, that should boost hill climbing potential by 165/155 = 6%, so a 10.6% slope instead of 10%.  This is essentially nothing, of course, and the fact is that freedom from balancing is powerful at low speeds.  For these two reasons, I consider even the sporty Bullitt to be a poor choice for moving kids on steep hills.

(Of course I would buy a Bullitt to find out, if I could justify the expense.)

Consider the effect of carrying just one child, lets say 15kg of kid, no cargo, 75kg rider and 35kg of Nihola for 125kg.  Compared to the empty trike, this only harms climbing by 110/125 = 12%, so if you could climb 15% empty you can climb 13% with the kid.  I've often been surprised when I try to race up a hill with a "lightweight" empty Nihola, because I can't go nearly as fast as I feel like I should be able to.  The 15kg kid makes less than a single gear of difference.

Wednesday, January 15, 2014

Niholas off road

A nice thing about bikes is the freedom.  The rider can do whatever they like with it.  For example, taking a cargo cycle off the pavement, maybe even way off the road.  Its a crazy idea.  Imagine taking a minivan into a mud bog: it would get stuck immediately, dirty inside and out, would be expensive to retrieve, and might be damaged by impacts, scrapes, water, even overheating of components.  But on your cargo cycle, there's nothing stopping you except your level of enthusiasm.

Relaxing path.
When the nose hits the mud, you stop.
In the world of cargo cycles according to Ray, only those with front boxes matter, and of those there are just a few kinds that matter.  Of course there is the Nihola, but also the Bullitt occupying the go-fast end of the spectrum and Christiania trikes at the utilitarian end.  Also there is the Dutch angle on this, the WorkCycles Cargobike springs to mind, but its as heavy as a trike without the balance advantage, so it is best left to boring tasks on firm, level ground.  This, according to Ray.

A Nihola is particularly well suited to going on crazy adventures with kids.  This is mostly due to two things: (1) unified frame (2) three wheels.  You can find larger three-wheeled conveyances (Christiania), or faster two wheeled ones (Bullitt or a long-tail), but a Nihola is (IMO) the best platform for hauling your offspring out into the local tamed wilderness in search of righteous mud.

But let me quality that a bit.  A Nihola is unlikely to be much fun where a mountain bike can't be ridden.  The tamed wilderness should have sufficiently firm and smooth ground, moderate to mild hills, mild side-slopes, 90cm+ gaps between trees, and relatively few fallen branches.   Mud, roots and rocks are OK in moderation.  In Denmark, this means just about any mountain bike path I've seen, plus a lot of walking and horse paths, and sometimes the forest floor itself.  So lets get started.

Slopes.
Climbable.
Just how nuts can a person go on their Nihola out in the (tamed) forest with two kids up front?  This will depend in part on some specifications of the Nihola in question: 1) low gearing, 2) grippy rear tire, 3) lowered inflation pressure in rear tire.  Also one should not neglect to put some weight over the rear tire: snacks, water bottles, spare clothes, diapers and so on.  Finally the driver needs to understand: 1) balance, 2) rocking, 3) wheel placement, 4) ground clearance, 5) approach angle.  With these points in mind, with maybe 40kg of children in the box, I have gone through mud that mountain bikes avoid, up hills that mountain bikes struggle to climb, on many km's of winding paths, and gained many hours of happy children time.

So to start with the mechanical side of things, a person needs low gears for the most pleasant Nihola offroading experience.  I can say from experience that 15 gear-inches is a lot better than 21 gear-inches, which is a lot better than 26 gear-inches.  Its also convenient if your gearing solution: 1) doesn't break into bits under heavy loads, 2) lets you roll the pedals backwards freely, 3) lets you change gears while stationary.  (That's because if you start a hill in the wrong gear, you can quickly become stationary.)  Shimano Nexus 8 or Alfine 8 is almost certainly the most sensible choice.

If your ground surface is wet or soft, knobby tires are a really good idea.  Relatively smooth tires, such as a Nihola is delivered with, give up quickly off pavement.  On a hill, one can often work around a lack of traction by rolling a bit backwards downhill in order to attempt a new approach.  In mud, a lack of traction leaves rocking as the only escape short of dismounting and pulling.  Lowered tire pressure in back is a useful traction aid, along with some weight on the cargo rack.  I suspect the Schwalbe Marathon Plus MTB is an excellent choice of tire.  Either the 26x1.9" or 26x2.1" version should fit in the frame, but the fatter one will be a close call.  My own experience with this comes from a 26x2.1 Nokian Extreme 294 (a winter tire), and I have a 26x2.0 Schwalbe Marathon Tour that I intend to try this summer.

This thin wet grass on greasy mud would only need a little slope to stop an unprepared Nihola.  But we are prepared.
So to conclude the mechanical side of things, we can say there isn't a lot to do.  Get the lowest available gearing, a knobby tire, lower the inflation in back, and carry something on the cargo rack for best results.  (The cargo rack also makes a good handle, and should be considered essential by any serious owner.)  Driver technique is more complicated.

First of all, its good to keep the rubber on the road.  Happily, children in the box have a powerful stabilizing effect.  Not so happily, weight on the cargo rack has an opposing effect, though a less significant one.  Also happily, with three wheels, the rider is free to get into positions which are atypical for a cycle of any kind.  For example, I have sometimes pedaled with my behind next to the saddle, not on it.  Balance downhill is pretty easy, although a few times I was afraid of tipping the whole trike over its nose, not just nose-down but entirely upside down, and so I did what I could to sit as far back as possible.  Balance uphill is easy so long as there is no side-slope.  An uphill side-slope renders a Nihola helpless embarrassingly easily, because the rider's weight can easily end up being outside the balance triangle formed by where the tires contact the ground.  So when climbing a steep hill, the rider needs to constantly be aware of the danger of tipping.  As the rider's body moves here and there while turning the pedals, the tipping risk changes.  The possibility of doing all pedaling with only the up-slope foot is one reason that being able to roll pedals backwards is an advantage.

Does that look like a hill?  Zero of four MTB's that we saw biked all the way up it.
Rocking is basically a trike-only trick, and very effective.  Its not so hard.  The rider throws his or her weight forwards and backwards while using the pedals to assist.  This can be an effective way to "hammer" through mud and snow, in addition to being handy at stoplights.  Again, pedals that freewheel backwards are helpful here.

Wheel placement is important for a number of reasons.  I'm not a mountain biker, but I think we can say that riding a Nihola is "technical".  You go slow and pick the places where the wheels will work best.  Things to consider include balancing, finding small climbable parts of the terrain, trying to have only one tire climb any obstacle at a time, avoiding crashing the steering components (under the box) into rocks, keeping the nose clear of the ground, and (depending on the gearing) arranging for the pedals to be in the right places at the right time.

Closely coupled to wheel placement is the issue of ground clearance.  The lowest point of a Nihola is actually a pedal at the bottom of its travel, and these can definitely come into contact with nature.  The steering arms are another possible point of concern, as are the linkages from the steering arms to the plate at the bottom of the steering tube.  Often the most exposed point is that plate, which is located at basically the central point between the wheels, and ripe for high-centering.  The plate seems to be well made, but I have actually bent it on the blue Nihola while navigating down some rocks.  Still works...

There is more.  The approach angle of a Nihola, or in other words the steepness of slope that the nose can clear, is a point of interest.  The nose of a standard Nihola sticks out pretty far (though not as far as the 4 seat model).  Its a common place for me to loose paint, sometimes even in civilization.  In the forest, if the nose hits the mud, its like a ship running aground.  Dismount and pull.  At one point I wanted to get a round-box Nihola, which has no protruding nose, for the purpose of driving in the forest with the kids.  That model is generally intended for older people who have difficultly with balance, so there would be some irony in mountain biking with one.

So, where does all this leave an adventurous Nihola rider?  Its still harder to take the kids onto the mountain bike trail than it is to take just yourself.  With two kids, a person could easily end up pedaling 60kg more than they would solo on two wheels.  You probably don't want to be on a trail with long uphills.  Some trails are easy, some are fun, some are really a pain, you'll know when you try.  Regardless of that, kids will likely have a good time.  Oh, and wear your rubber boots.

Mmm, mud.
A rest for the weary.
Pleasant tour with two kids.