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One Ring Front + Geared Back =Chain Rub?(7 posts)

One Ring Front + Geared Back =Chain Rub?Dan Q
Sep 12, 2002 5:49 AM
I want to build my road bike commuter to use just one chainring (no Ft. Der.) and a cassette in back. I want to use the big ring as a guard on the outside and a third eye chain keeper on the inside. In back I don't know how many speeds yet but probably Shimano-9. Does anybody know if this set up will keep the chain from falling off? What about chain rub? Will I be doomed to only using the middle 4 gears in back to avoid it? How about dedicated chain guards (Spot, TA)? Are they spaced further out from the small ring to help avoid chain rub when there are gears in back? Many Thanks!
re: What will it rub against? nmdzrider
Sep 12, 2002 6:33 AM
Why the "Chain Guard"?Gregory Taylor
Sep 12, 2002 7:16 AM
If the chain line is set up correctly with your single front ring, you should have no issues with the chain falling off up front. I'd set it up with the front ring in line with the fifth or middle cog out back. The only small concern is the chain angle when you are in either low or high gear causing excessive wear. Frankly, I wouldn't worry about that either.

I have a buddy that had this set up on his commuter bike. Worked fine.
I run one ringSteve_0
Sep 12, 2002 7:20 AM
nothing to rub against; wont fall off even without a 'guard'. unsure of your concerns; if nothing rubs with two rings, certainly nothing will rub with one.

I do limit the deraileur on the outside (using chainring on the inside) just to limit chain wear/stretch.
Check at cyclocross suppliersbrider
Sep 12, 2002 7:25 AM
Many 'crossers run one chainring, and have something similar to a Rock Ring on both sides of the chainring. The main reason isn't for retaining the chain for shifting reasons, but that in 'cross, you're running a long cage rear der., and chain slap can sometimes cause the chain to fall off in the rough stuff.
leaving big ring on?climbo
Sep 12, 2002 7:51 AM
then why not keep your front der and use both rings? I use a single ring on my cross bike and I leave my front der on, if I get chain rub I trim the front der to get rid of it AND it keeps the chain on.
I Guess NotDan Q
Sep 12, 2002 11:14 AM
I was under the impression that I would need something to keep the chain on. Apparently this is not a problem even when riding off road. As for why not keep the big ring and front derailleur on, it's because I don't have a front derailleur for the bike.
Thanks for all the input.