anomaly

I converted a Jamis Aurora cyclocross the other day using some parts I had laying around, and it went pretty piss poor. I was hoping that 40/16 would be a magic gear, given that is what I had on hand and it has vertical dropouts, but I didn't have such luck. The chain can be knocked off by tilting the bike over rapidly. I believe a half-link will work, so I am going to give that a shot. If that doesn't work going up a tooth in the front should put it where it needs to be, then once the chain stretches I would go to a 17 in the rear. In addition the 175 crank arms + toe clips give quite a bit of overlap for the front wheel. It's a shame, the bike rides like a dream otherwise. I might put the Sora group back on the Jamis and sell it, and put the SS stuff on a Pista frame that is too big for me and sell that, then pick up a group buy Iro frame and build it up. Decisions decisions...

goldener

yea, guessing on magic gear ratios usually doesn't turn out that great....

anomaly

Oh well, I tried and learned my lesson. My big decision is how much money I want to put into this versus something else.

killsurfcity

how far off were you? could a half-link in the chain sort that out?

noriel

You're better off starting on an easier frame, like a track frame or a cyclocross fram with track ends or horizontal dropouts. Leave the Jamis alone. I'd rather have two good fixed gear bikes, instead of 4 so-so builds that may never really be finished.

dustinlikewhat

wait was this fixed or single speed? if single speed just get a tensioner.

anomaly

I would like to run both, and it def isn't worth $150 for an Eno hub

dustinlikewhat

if it's a great fitting/riding frame, it is. or just slap the gears back on it and save up for a frame with track ends.

odie91

Bad idea on the chain stretch. Although it compensates for the distance between front chainring and rear sprocket, the distance between teeth on a gear is constant. Riding a stretched chain will wear out your teeth really fast.

jjvw

Waiting for your chain to stretch to move up a gear is a bad idea.

anomaly

Good to know, then where exactly does a chain 'stretch' if the distances remain constant?

idcruiserman

Pin wear.

oldsprinter

Get a 1/4 link for now

noriel

I had an ss mtb conversion and the chain tension was so tight that it wore out the drive-side races on my rear hub. It was a bike that I had a "magic-gear" figured out.

goldener

roller/bushing wear

squeakywheel

Adding a tooth will move the rear axle forward 1/8 inch.

Adding a half link will move the rear axle backwards 1/4 inch.

Adding a full link will move the rear axle backwards 1/2 inch.

Measure your error with what you have now and then figure out which combination of adding / removing any of these three will put the axle in the dropouts.