Wednesday, May 6, 2015

Shimano BR-IM80-F, BR-IM50-F, BR-IM45-F

Its been most of a year since I wrote anything.  Life goes on.  I've been doing lots of commuting on an official Danish-name-sticker bike, straight bar, fenders, cargo rack, lights, gear hub, etc.  Its got a Shimano roller brake in front, attached to a dynamo hub.  This is lovely except that it isn't much good for stopping.

I noticed some years ago that more impressive-looking roller brakes were available.  My bike had a BR-IM50-F.  I wanted one such as a BR-IM80-F, but I could find none for sale.  None online, none in bike shops.  Generally they were not even available on bikes in Denmark or Norway.  I had bike shop owners argue with me about whether one would even fit my bike.  I had people say it was all the same, no point in switching.  I had noticed that sold lots of them, but they didn't really do small part orders.  Then, I actually went to Amsterdam.  I even had to go to the workcycles shop twice to get through to a mechanic without too much waiting.

So, now I had a BR-IM80-F in my hands.  In my carry-on at the airport even, by accident.  That got a raised eyebrow.

Anyway once home, I performed the swap.  Possibly the easiest part swap this side of a pedal with greased threads.  Take off the wheel, apply a 17mm (I think) deep socket, change the shift cable to a new-style cable (had one laying around), done.

So did it improve braking performance?  No.  Not in any noticeable way.

Here I have laid out a BR-IM50-F, BR-IM80-F and BR-IM45-F with their business sides exposed.  The two newer ones appear to be identical except for the cooling surface, and the older one is just damned dirty, also possibly a little worn.

So hopefully by writing this down in the sight of a search engine, others can be informed.  These roller brakes are generally not so useful on hills, and getting a "bigger" one doesn't help.  I have another bike which, like the one I just modified, has only the potential to mount hub brakes.  On that bike I mounted a Sturmey Archer XL-FD (a 9cm drum brake hub), which fits perfectly, brake arm and all, and its stronger though perhaps a little more temperamental.  (Niholas use the 7cm version of that drum brake.)  Going the Sturmey Archer route does appear to require building your own wheel though, not a big supply of pre-fab wheels built on drum brake hubs.