Search This Blog

Friday, June 24, 2011

Testing a DIY 1x8 trail bike

Due to some unfortunate bike-on-tree action at Mohican state park, my favorite single-gear trail bike is kaput. Tight summer funds (due to overlapping apt. leases) inspired me to dig out the frame that first introduced me to mountain biking. I'm not looking forward to running gears again; I've become quite accustomed to life without chain slap and trail-side derailer re-engineering.

As this frame has vertical dropouts prohibiting a proper single gear setup, I've decided to run a 1x8 with wide ratio cassette (11-32t) and my single-speed crank (36t). The 36/32 is plenty low for crawling up hills, and the 36/11 is overkill for going down. The middle of the cassette gives a 36/21 and a 36/19, either of which are acceptable single-speed ratios. Best yet, I can get away with using a short cage road derailer due to the short chain length. I found an old SunTour SVX (http://www.disraeligears.co.uk/Site/SunTour_SVX_SS_derailleur_(7300).html) which has very stiff springs for its original use on friction-shift bikes. I don't seem to need a front derailer/chain catcher right now, as my bash ring prevents throwing the chain to the outside, but I may fabricate a simple one later like this:(http://johnmcallister.blogspot.com/2009/03/couple-of-cycling-diy-projects.html) if I find myself throwing the chain to the inside.

My preliminary test-rides on campus are promising. Shifting is very tight and precise, with very little chain slap. I'll give a report after my first "real" ride.

2 comments:

Adub said...

This is a very well written piece! Look forward to hearing how the bike runs on a trail!

Anonymous said...

some of those old SunTour's have an extra hole drilled into the cage that can get you even more spring tension. Same concept as the multiple spring holes in canti bosses.

Post a Comment