Changing Cassette
- Thread starter BikerMat
- Start date
If you're struggling on your 23T then you need a bigger one (or else lots more ridingBikerMat said:
). If you are using a recent shimano road RD then you could even go to 12-27. This should make a fair difference (39 inches instead of 46 inches, assuming a 39T chainring).
BikerMat said:
It will give you a low gear that is about 13% lower. This will allow you to spin about 13% faster on the hills (assuming roughly the same power output) or drop power output by about 13% and spin with the same cadence you do now.
To estimate if this is enough, measure your cadence on the hills at your desired effort level. Then pick a target cadence - I usually shoot for a lowest cadence of 60 rpm. If your target cadence is more than 13% larger than your actual cadence, a 12-26 will not be sufficient.
Triple, just go for a triple crankset. Lots of chainrings to choose from, 28, 30, 32, this will give you 3-4 gears lower than the 39 front - 23 rear.
http://www.scvimports.com.au/2003-4cat/2003-25.pdf
39:23= 1.70
30:19=1.58
30:21=1.42
30:23=1.30
28:17=1.65
28:19=1.47
28:21=1.33
28:23=1.22
By changing the cassette to a larger low gear, say 25 or 26 or 27t, you will loose the benefit of the close ratios in the middle range, probably the 16 and 18 tooth cogs. I have just fitted a 13-23 9 speed and will be changing my chainrings to 52/39/28 to get the hill climbing ability back. I spin at a higher cadence, 90 where possible, so my bike is geared lower overall.
http://www.scvimports.com.au/2003-4cat/2003-25.pdf
39:23= 1.70
30:19=1.58
30:21=1.42
30:23=1.30
28:17=1.65
28:19=1.47
28:21=1.33
28:23=1.22
By changing the cassette to a larger low gear, say 25 or 26 or 27t, you will loose the benefit of the close ratios in the middle range, probably the 16 and 18 tooth cogs. I have just fitted a 13-23 9 speed and will be changing my chainrings to 52/39/28 to get the hill climbing ability back. I spin at a higher cadence, 90 where possible, so my bike is geared lower overall.
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