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Minimum medium ring in a triple crankset?(5 posts)

Minimum medium ring in a triple crankset?Chechu
Apr 10, 2003 9:53 PM

Here is a fast question:
Could I fit a 39 tooth (or even a 38t) as medium ring in a triple crankset?

Thanks in advance!

depends on the bolt circle, but probably yescory
Apr 11, 2003 5:59 AM
I think the minimum on newer Shimano cranks is either 38 or 39. For most riders, I think it's a good swap--I'm using a Sugino crank with a 46-36-26 triple, and I really like it. Gives all the gears I need without all that 53-12 stuff I never used....
If you get a Bike Nashbar catalog (probably on the website, too) it will give instructions on how to measure the bolt circle diameter, with a list of what will fit.
Apr 11, 2003 6:20 AM
Shimano, at least Ultegra, you could put as low as a 38, but it won't be ramped and pinned on the inside, plus the big ring won't be designed ideally to pick up the chain from the middle. It will work, but shifting might be a little slower.

Dura Ace, no change is possible. The middle ring is a 39, but it has tabs to bolt on the granny. I'm not aware of any replacements.

Record comes with a 42, and I've tried a 39 (smallest that will fit on Campy Record), but shifting was quite a bit worse from the granny, with no inside ramps and pins.

If you have something other than the above, it's going to depend upon what you have.

Here are some rings listed at Peter White cycles, however I've ordered from him twice and he completed ignored my orders; it's a handy reference to see what's available, though:

You can probably go as low 33t...timfire
Apr 12, 2003 3:09 PM
...but it will depend upon the BCD, as others have said.

The standard triple crankset outer ring BCD is 110mm. According to Sheldon Brown, the smallest chainring you can get with a 110mm BCD is a 33t.

If your crankset has a 130mm BCD (the road double standard), then the lowest you can go is a 38t.

Thanks everybody! [nm]Chechu
Apr 13, 2003 12:35 PM