I'm wondering what cassette cog ratios everyone out there uses and why. I have a front crankset with 39/54 and a cassette cog with 12/23. I see a lot of pros use 11/21 or 11/23. This may be a dumb question, but what are the advantages of those ratios? Is it simply that tighter ratios on rear cassettes are better on flat courses and larger ratios oare better on hilly courses? I'd like to have this matter explained to me. Thanks.
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Re: Cassette Cog Question [tripoet]
[ In reply to ]
I'm certainly no expert, but I just changed to an 11-21 and 39-52. My top priority race in BSLT 1/2 IM. The race is extremely flat but with 8 very steep short hills. In addition, where I live and train is the definition of flat. I chose this gear set b/c it will give me a very tight range around my goal race pace. Since it is a flat course I don't need a huge range of speeds.
It appears to be the consensus of everyone I've polled that in long distance racing you should stop pedalling much after 30 mph on the downhills, thus I don't need more than a 52x11 which is in the 32mph range.
My bike came with 32x42x52 and (I think) a 12-28. You could climb a vertical wall with a 2 ton gorilla on your back with this setup. I just didn't need that kind of climbing power for the courses I race. I definitely noticed the big jump in gearing when changing from on speed to the next on this setup.
It appears to be the consensus of everyone I've polled that in long distance racing you should stop pedalling much after 30 mph on the downhills, thus I don't need more than a 52x11 which is in the 32mph range.
My bike came with 32x42x52 and (I think) a 12-28. You could climb a vertical wall with a 2 ton gorilla on your back with this setup. I just didn't need that kind of climbing power for the courses I race. I definitely noticed the big jump in gearing when changing from on speed to the next on this setup.
Re: Cassette Cog Question [tom]
[ In reply to ]
Thanks Tom, very helpful as usual.
What size wheels do you have?
Traditionally, a 700c road bike had 53/39 front rings and a 12-23 cassette. With 650c wheels, people when to 54(5)/42 in the front and 11-23 or 11-21 in back. The 54/11 is a pretty big gear and overkill for most people. The difference between the 11-21 and the 11-23 is the 16t cog, which for me, can be critical for flat races. If I was going to be riding a hillier course, I would go to a 12-23 rather than the 11-23 to keep my 16. If you are looking at a super hilly course, going to a 12-25 and smaller chainrings would be a good idea.
For me, there is nothing worse than spinning 100+rpm in one gear, but not being able to spin 80 in the next.
Traditionally, a 700c road bike had 53/39 front rings and a 12-23 cassette. With 650c wheels, people when to 54(5)/42 in the front and 11-23 or 11-21 in back. The 54/11 is a pretty big gear and overkill for most people. The difference between the 11-21 and the 11-23 is the 16t cog, which for me, can be critical for flat races. If I was going to be riding a hillier course, I would go to a 12-23 rather than the 11-23 to keep my 16. If you are looking at a super hilly course, going to a 12-25 and smaller chainrings would be a good idea.
For me, there is nothing worse than spinning 100+rpm in one gear, but not being able to spin 80 in the next.