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.