Shimano cassette question

Triathlon Forum
1

I am doing an olympic distance race in May this year in which the cycle course consists of 3 laps, each of which has a section up and back down the same 3 mile hill. The other 2 and a bit miles of each lap is flat.

As I see it, this means I will need a) a reasonable range of climbing gears, (b) one big gear for the descent and (c) some slightly smaller but still big gears for the flat (I usually ride a 53x14 on the flat, conditions permitting).

I have two cassettes for my bike: a 12-25 and a 11-21. The groupset is Shimano. Whilst the 12-25 seems the best choice, I wouldn’t mind having the 11 for the descents.

Does anyone know if it is possible to replace the 12 tooth ring on the 12-25 cassette with the 11 tooth from the other cassette. Has anyone done this themselves? Will it work or is it likely to mess up the shifting?

All advice gratefully received

Tom

2

I would suggest staying with the 12-25, but make sure you hammer up and OVER the hill. You will gain more by accelerating quickly over the top, than you will by going 39 instead of 36 down the back side. Get up to speed and then recover.

3

I would agree and tell you to stick with the 12-25 and not try to modify it to an 11. I have the range of cassettes and find that the 11 only comes in when you have a looong downhill or you ride a low cadence.

Jimmy S.

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