August 19, 2009

Singlespeed mtb, and housing

I sent my shock off for servicing last week. But since I can hardly go a week without mountain biking (or I'll risk my mental health, which is unstable to begin with) I had to ponder my options. Sure I could borrow some of the demo bikes we have at the shop, but I've been riding those for quite a bit and I wanted to try something different. So, out from hibernation came the Cannondale that I've had since 1998. This bike (a rigid M400 mountain bike) has gone through many transformations over the years and has served me well. The last incarnation was a singlespeed version that I used for a cyclocross race last year and for commuting in the snow last winter. I was running a 34x16 gear on it for that purpose but decided to lower that a bit, so I threw on a 32t chainring and headed for the dump. I've ridden this bike as a singlespeed, ever since the original drive train finally gave up the ghost a few years ago, but I've never ridden it on mountain bike trails as a singlespeed. Although in it's early years it saw a lot of action on the mountain.
The trails at the dump are not friendly for heavy gearing as I soon found out. I managed to ride up most of the trails that were not to steep, but once I got into technical and steep climbs, things got a little rough. This resulted in much sweat and many stops. I immediately decided I should lower the gearing a bit but I must say that I was blown away by how much fun this was. Every little thing is a challenge on that rig, even just riding on the fire roads. I enjoyed being forced to ride smoothly, or I would pay for it. I rode up to the top of Twister and that's where I discovered a bit of a problem. My fancy pink "brake" housing was splitting on me..."Now why was this happening," I thought and then realized my rookie mistake. I had been so mesmerized by the colour that I didn't check if the housing was a brake or a shifter cable when I installed it after salvaging it from the garbage can at work. Using a shifter housing for a brake cable is not a smart idea, since shifter housing is designed to have as little friction as possible and for that it sacrifices strength. there was a good story on this in Urban Velo a while back: Brake VS Shifter Housing
But I digress. I temporarily fixed the brake issue by switching the housing around, back to front, which provided me with enough stopping power to get down the hill. The day after I rummaged around in the parts bin and found an old 18t cog and some yellow (!) brake housing and went out again, after work. That gearing is much better, but since the cog was out of a cassette, it was not quite as wide as the singlespeed cog that was in there before. I did not realie this until I was on the trails and kept throwing my chain off. I solved that problem, by sacrificing an inner tube and having my chain tensioner pulling up instead of down, thus engaging more teeth on the cog and getting rid of the annoying chain throwing issues. That configuration worked well, and the hills were a little easier, so I'll keep that setup for now.

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