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Chain ring is touching my frame
Hi yall.
I just replaced my chain ring and crank set on my converted single speed bike, but the new ring (which is the same size as the old one -44 tooth) just starts to scrape the frame bars, when it is installed. Is the something i can do, like some kind of a washer that i can insert onto the under bracket so it gives the chain ring some clearance? I am totally puzzled as to why the new one wont fit.

Thanks for looking.
Different cranks sit different distances out, it's not uncommon to have to change the bottom bracket when you change cranks.

You can put a thin spacer between the drive side cup of the bottom bracket and the frame to move the crank out a little bit. A cassette spacer will work for this. But you can't go more than 1-2 mm or you risk the BB ripping out the threads of the frame. Maybe shouldn't even do it at all if the frame's threads are at all beat up or a loose fit.

The "proper" way to fix this is to bet a BB with a longer spindle. measure how much you need to move the crank out to get a nice straight chainline, double that, and then add it to the length of the current BB to know what size to get.
Dave is correct.

But there is a "cheater" option if you have crankset similar to this:
where the chainring is bolted to the spider. You can move the chainring to the other side of the spider.
Cheers guys. I thought i would have to get a BB as well. Just wanted to check. The BB on there at the moment is still good, so i may just try the spacer thing first and see.


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