Chain ring is touching my frame

[doomsdaysignals]

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.
Peace.

[DaveM]

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.

[nfmisso]

Dave is correct.

But there is a "cheater" option if you have crankset similar to this:
http://www.amazon.com/Vuelta-Pista-Track-170mm-Alloy/dp/B004Z8C204/
where the chainring is bolted to the spider. You can move the chainring to the other side of the spider.

[doomsdaysignals]

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.

(<_>)