Hello Forum,

Like the subject line suggests, I'm in a bit of a dilemma with my campy 9 speed setup. I have a 13-26 and a 12-21. Both record, both 9 speed. However, I'm doing a ride where I need the 12 and the 26. Only the top two gears are on a carrier, all the other are loose cogs. Can I/should I just switch the 13 with the 12 (both cogs have that knurled lockring interface)? Or should I take out one of the middle cogs and put the 12 on top of the 13? Any advice would be greatly appreciated.

Thanks!

I'd take out a middle one, but I don't think it matters. On reflection, this is an edit. I have done the same thing. If your 13 is not a plain cog, you probably ought to just switch the 13 for the 12.

Get a 12-25. You'll hardly notice the difference between a 25 and 26.

The cogs are all timed relative to one another. Swapping or removing cogs will result is poor shifting.

If you really need the 26, then get a 12-25 and swap the 23-25 pair for the 23-26 pair.

I'm doing a ride where I need the 12 and the 26.

Just doing a reality check here. 100 rpm in a 53/13 w/700c wheels is 32 mph. Spun out, that gear would easily give you 35 mph plus. A 53/12 would give you 38 mph. Due to the very large aero advantage of a tight tuck (hands on bars near stem, elbows and knees on the top tube, chin nearly touching the stem), you can coast more than 4 mph faster on a 6% grade. On a 4% grade, coasting in a tight tuck will still be 1 mph faster (33 vs. 32 mph) than pedaling a 53/13 at 100 rpm and 170 watts. Coasting in a tight tuck is as fast as pedaling when the grade is about 3.2%, which is 30 mph, or 100 rpm in a 53/14 at 170 watts. In most circumstances, coasting downhill is just as fast and a lot less effort than pedaling. You may need that 12 cog to chase down breaks in a race or the local hammer ride, but otherwise, don't kid yourself. BTW on that 6% grade, pedaling at 275 watts will increase your speed 2 mph, half as much as the tight tuck will get you. 275 watts is 24 mph on flat roads. Do you really "need" a 12?

Just doing a reality check here. 100 rpm in a 53/13 w/700c wheels is 32 mph. Spun out, that gear would easily give you 35 mph plus. A 53/12 would give you 38 mph. Due to the very large aero advantage of a tight tuck (hands on bars near stem, elbows and knees on the top tube, chin nearly touching the stem), you can coast more than 4 mph faster on that grade. On a 4% grade, coasting in a tight tuck will still be 1 mph faster (33 vs. 32 mph) than pedaling a 53/13 at 100 rpm and 170 watts. Coasting in a tight tuck is as fast as pedaling when the grade is about 3.2%, which is 30 mph, or 100 rpm in a 53/14 at 170 watts. In most circumstances, coasting downhill is just as fast and a lot less effort than pedaling. You may need that 12 cog to chase down breaks in a race or the local hammer ride, but otherwise, don't kid yourself. BTW on that 6% grade, pedaling at 275 watts will increase your speed 2 mph, half as much as the tight tuck will get you. 275 watts is 24 mph on flat roads. Do you really "need" a 12?


I wish you could provide some hard data to back up your crazy opinions... oh wait, nevermind.

As always thanks again to KI :thumbsup:

I normally (>90% of the time ride with a low of 13T in the back) and the only time I would like more would be on long slightly downhill decents where I can get in an aero position and turn the cranks relatively slowly and still pick up some speed. These occurrences are almost never.

Hello,

So what i ended up doing is taking out a middle cog from the 13-26, and also removing the knurled 13 and replacing it with the 13 from the 12-21 cassette. Worked PERFECT. No trouble with shifting, and the ratio was just right. On the same course last year I died without an 11, but luckily, the 12 was sufficient this time.

As for my "need" for a 12. Truthfully, i'm always most comfortable with an 11 in these situations. The ability to comfortably spin at low rpms is a definite plus in certain race situations. For some background: I am a cat 1, and the race in question was the boulevard RR. Appreciate your concern though....