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Singlespeed & Fixed Gear - Crankset trouble '86 Bridgestone conversion

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han-gan

01-22-09, 09:21 PM

So I have this '86 Bridgestone Mb-3 that I am currently converting to fixed and I need some help. A friend hooked me up with some parts and I bought a Soma Hellyer crankset off of him as well. I've had a 26'' rear wheel built on a surly hub meant for a frame like mine but the chain line is way off. Even with a new bottom bracket and short spindle the chain line with the Hellyer is ugly. I can't mount the chainring on the inside of the spider guys because there is no beveled edge or zone meant to have something mounted on it. I've looked for another crankset of about the same quality that I can mount the chainring on in a way that will remedy my chainline problem but I'm having a hard time finding something that works. Any suggestions on a crank set that has a low profile, in other words, one that will be closer into the frame and allow for better chainline. I do appreciate it
Willy Beamin

dayvan cowboy

01-22-09, 09:28 PM

try a different sized bottom bracket

han-gan

01-22-09, 09:31 PM

I've put in a bottom bracket to get the chain ring closer in but it only helped so much...

dmg

01-24-09, 01:18 AM

Any chance that you're mixing MTB and track parts?

MTB BB shells are 73mm, while road bike BB shells are 68mm. Not sure about the Bridgestones, but I'm assuming it's got a MTB sized shell. If you're using a road BB in a MTB shell, that could be your problem right there. If not, you'll need to track down a 73mm square taper BB that has a 110 mm spindle for a 42mm chainline, or if you're using the surly big (130mm) hub, 115 for that hub's 47mm chainline.

Pics would probably help.

pyze-guy

01-24-09, 02:52 PM

Did you get the mtb surly hub, 135mm size? I have one and am able to run my chainring on the outside of the spider for an excellent chainline. My 130mm hub on my othe bike needs to have the chainring on the inside of the spider, and even with the shortest bb it is still about 3 mm off. Not enough to cause any problems though.

You can try the 67.5mm rule (http://forums.mtbr.com/showpost.php?p=4758914&postcount=12)to see how things are lined up. Flipping the cog can help as well, making sure the flat side is facing out.