The Girlfriend’s Bike: new gearing pt 2Comments
by Mark V on Jul 03, 2009 at 12:22 PM
So I finally got a chance to finish out the mods on my girlfriend’s Kappa BMX bike. Last year I morphed the steel BMX racing frame into a pseudo Schwinn Stingray with ape-hanger handlebar and braze-ons for the banana seat and sissybar support; this time I stretched the rear triangle to fit a Sturmey-Archer 3sp internally geared hub with drum-brake.
I had to re-space the rear dropouts from 110mm to 120mm for the hub, which isn’t something I would have tried with a more delicate, lighter gauge steel bike. However, I have a pretty good feel for what I can get away with on an alignment table.
The hub came with a number of cable accessory options, and I chose the least bulky seat up. I bent the shifter cable support so that it tucked into the rear triangle for better heel clearance; the 380mm chainstays are much shorter than the typical bike that this hub would be installed on.
Aesthetically I would have preferred that the frame would have had the proper cable stops, but sometimes you just gotta be happy with “good enough”. I used some Jagwire self-adhesive housing guides on the downtube and chainstays. I’ve never used this item before since I didn’t think that such a thing could actually work. The Jagwire guides seem to use some industrial strength sticky foam tape to adhere. I was pretty impressed how much force it took to remove one that I decided was in the wrong place. To be safe, I added a heavy-duty zip-tie at the spot where I thought the cable housing would most likely get snagged, at the downtube after the loop from the levers.
When I first tried the new set-up, I had used a brake lever intended for side-pull caliper brakes and cantilevers, but after riding the bike down Capitol Hill to the U-District, I decided that the drum brake really wanted a long-pull lever. The drum brake did work, but it didn’t quite develop enough power before the lever run out of throw. So I re-fitted the Shimano DXR lever, which also had the critical advantage of being really shiny. The brake cable runs to a fitting made from a recessed brakenut, as suggested by SBS’ Val. I invested a ridiculous amount of time getting it just right, but the end result is way better than the stock item.
I’m gonna suggest that my girlfriend and I take a little bike ride on today’s holiday. She’s never had a bike with multiple speeds, so I’m really curious how she’ll take to it. Mainly she wanted a braking system that didn’t howl like a stampede of cafeteria chairs on a linoleum floor; the drum brake works like a charm.
My initial impressions of the hub are that the drum brake works competently, but that the hub/shifter really struggles on downshifts under load. On an incline, one needs to really soft pedal to wrestle the shifter into a lower gear; otherwise the shifter refuses to move like it was locked out. Shimano’s Nexus and Alfine are much better in this respect. It it nicely fills the bill for my girlfriend’s bike, but the shifting would drive me crazy on my own bike.