Inner Chain Ring dilemma

sy · 24-02-2009 12:56pm #1

Friend has mistakenly bought a bike with 53/39 chain ring combination (online) and just wondering if it is possible to fit a smaller inner ring say 36. Will there be a problem with derailleur etc. Thanks

rob1891 · 24-02-2009 1:03pm

A Shimano 53/39 setup indicates a crank with a 130mm BCD. The minimum inner chain ring you can fit on this type of crank is 38 tooth available from the likes of Stronglight. If it is a campag crank, 39 is the absolute minimum.

To get easier gears he should look to replacing the rear cassette with a wider ratio one.

E@gle. · 24-02-2009 1:22pm

to big of a gap i reckon from 36-53

blorg · 24-02-2009 1:39pm

In order of increasing cost, look at getting a cassette with low gears (27T or the 28T from SRAM for Shimano, Campagnolo do a 29T) and if that isn't enough get a compact crankset- you have to replace the whole thing as the BCD (Bolt Circle Diamater) is different.

sy · 25-02-2009 8:59am

Thanks everybody for the advice. I had suggested the 28 block from SRAM but he needs a lower gear as he has a hip problem and has to sit in the saddle on any big climb. Blorg, is it possible to change to a compact combination and not have to change derlailleur etc? Also does anybody have the ratios for the 11/28 SRAM block, cant seem to find it anywhere. Thanks again

Morgan · 25-02-2009 9:17am

11,12,13,14,15,17,19,22,25,28

You can use the same derailleurs with a compact chainset.

blorg · 25-02-2009 10:59am

As Morgan says you can use the same derailleurs, at least I certainly hope so as I am planning on getting a 50/34 myself for the Alps. As far as I can figure out 50/34 12-27 will be 2T out of spec for a standard Shimano short cage rear derailleur. From what I've read It's generally considered you can go 2T out of spec safely enough. I am not sure about 50/34 with an 11-28 though, might be pushing it, might not. I am sure 11-28 would be fine with a 53/39 front though.

sy · 25-02-2009 11:21am

Thanks Morgan & Blorg, think a compact is his only realistic option. Hoping to use a 28 on a compact for myself as I hope to get to the alps sometime this summer.

TinyExplosions · 25-02-2009 11:40am

blorg wrote: »

I am planning on getting a 50/34 myself for the Alps.

Wuss

sy · 25-02-2009 12:37pm

What gear were you riding when you "beat Blorg up the Glandon"?:rolleyes:

TinyExplosions · 25-02-2009 12:46pm

sy wrote: »

What gear were you riding when you "beat Blorg up the Glandon"?:rolleyes:

I had a compact, but that's cos I'm fat and slow... that day, Blorg had a Triple!

Inner Chain Ring dilemma

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