Why are Chainring sizes so close together?

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Permalink Reply by Rich on March 6, 2009 at 2:28am

Because I had too much caffeine earlier and I'm geeking out on chainrings here are some intresting gear-ratio numbers courtesy of the www.Campagnolo.com gear-inch calculator:

38/46 X 13-26 3.06-7.42

36/48 X 13-26 2.9-7.74

34/50 X 13-26 2.74-8.06

With out the (legit) option of a 12-27 cassette the lap over seemed a little much with the standard 38/46 and a 13-26. Or is that what you want? Thanks.

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Permalink Reply by Echappe Equipment on March 6, 2009 at 11:44am

I would think that anything above a 46t big ring is going to be too much for you in Maine. Also, you should get used to spinning the gear a bit more. I would also get a FSA ring since you're going to wear out the rings anyways riding on sandy/salty roads and trails up there. Once September hits you'll need new chainrings and why spend a ton? Campy is nice and all, but you don't have a soigneur to wash you bike, or an equipment sponsor to change your chain every 1000 miles.

The difference between the rings depends on your fitness and riding style. I ride a 46/38 with a 11-23 cassette for dry and 12-25 for wet conditions. It works for me, my style and my relative race fitness when the season comes. I have friends who ride bigger and smaller gears and in the end of the day we are battling each other pretty evenly. So, ride what you like, but focus on the spin, base training and overall efficiency.

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Permalink Reply by Rich on March 6, 2009 at 4:57pm

Why would a 46 be too big? Do you mean on the circuits or on the road? Don't forget, I'm riding a 13-26 cassette.

But thank you for your input and it made me curious. Sooo . . . a 46T ring with an 11-23 cassette gives a gear-inch range of 4.19-8.77; 46T and 12-25 is 3.86-8.04; and 48T and 13-26 is 3.87-7.74. So my 48/26 is .01 (not much) gear inches taller than your 46/25, but both of your cassettes give you much taller gearing on your smaller sprockets, so you would blow by me. But it would give me the easier spinning you were referring too, which I have always done naturally. I'm a bigger guy, but I've just never been a masher. And I am looking into TA rings. I found them at a price close to what FSAs have been going for and I'm just not an FSA fan, but I know TA had earned a pretty good rep.

Another punching of numbers produces a 50T and 13-26 gives you 4.03-8.06. This puts the 50/26 dead between your 46/23 and 46/25, but with the 50/13 I get a 8.06, so I', just .02 (so next to nothing) taller than your 46/12.

I'm such a geek. But thank you for the info and reply. Now that I have done the numbers, I think I'm going to stick with the stock 34/50 rings. The cassette makes the difference. But we'll see how the mud interferes. I'm thinking when in race conditions the spread 'tween the rings would limit how much tention I can put on the chain, and I might lose the chain more.

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Permalink Reply by Rich on March 23, 2009 at 2:41am

Thanks again to Echappe for your advice. But can anyone tell me why the chainring sizes are so close together in CX. Standard seems to be a 38/46. Why are they so close? And where, if I ever wanted to, would I get "Campy compact" chainrings in this size. I've searched the web and I can't find a 46T outer. Not that I need one, mind you, but i'd be nice to know I could get it. You would think one of these companies making Campy compact chainrings would make standard CX ring sizes. But they don't. Not even TA. I have found 48T TA rings, but that's it. I know the easiest thing to do is buy an FSA Gossemer crankset, but no thanks. What would be nice is if Fulcrum made a CX crankset, but it looks like what I need is a seperate standard UT crankset with Miche 38/46 rings. But I can't find anyone selling anything but their track rings. Cyclocross world has TA 39/46 rings in stock though. pfft.

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