Cassette Size?

Peter Verdesi said:

I live in the northeast of the United States (New York) and it's a bit hilly here and just had a question about the size of cassettes. I took up doing triathlons last year but have been riding almost my whole life (the riding I've been doing up until a couple of years ago has been more in a cross training capacity as running is my strongest skill). I'm building up a race bike for the up coming triathlon season and decided that, due to the hills in my area, a 12/27 cassette would be the best option. Last year I was riding a bike with an 11/21 cassette and found that I could not push the gear going up some of the steeper hills. I know that the 12/27 and 11/21 are at the extreme ends of the spectrum for cassette size but my question is this; is the 12/27 cassette too big? What do the pros use in hilly races? I have not taken the bike out yet with the 12/27 'cause it's too damm cold here but what should I expect. Does a larger cassette shift sloppily because the gears are further apart? I know that a larger cassette weighs more and that the weight on the wheel is important but does it really make that much of a difference? Thanks.

Since you aren't a top level pro,what does it matter what they use? I use what it takes to get the job done. Roberto Herras used a triple to win a stage in the Vuelta.

Peter Verdesi said:

I live in the northeast of the United States (New York) and it's a bit hilly here and just had a question about the size of cassettes. I took up doing triathlons last year but have been riding almost my whole life (the riding I've been doing up until a couple of years ago has been more in a cross training capacity as running is my strongest skill). I'm building up a race bike for the up coming triathlon season and decided that, due to the hills in my area, a 12/27 cassette would be the best option. Last year I was riding a bike with an 11/21 cassette and found that I could not push the gear going up some of the steeper hills. I know that the 12/27 and 11/21 are at the extreme ends of the spectrum for cassette size but my question is this; is the 12/27 cassette too big? What do the pros use in hilly races? I have not taken the bike out yet with the 12/27 'cause it's too damm cold here but what should I expect. Does a larger cassette shift sloppily because the gears are further apart? I know that a larger cassette weighs more and that the weight on the wheel is important but does it really make that much of a difference? Thanks.

I'll take a stab at it and offer an opinion, but the simple fact that we're different riders using our bikes in different applications means take what I say with a grain of salt to be sure.

In terms of the effect a 12-27 is going to have on your wheel weight as opposed to an 11-21, you can effectively ignore it. More critical to the performance of your wheel would be the rotational weight, and the cassette is centrally located. Few extra grams on the overall wheel weight and overall bike weight, but its negligible unless you are at the highest end of fitness and every gram is critical.

I rode a 12-27 for two years and found myself in the 39-27 only on the mountains, and even then I tried to stay back in the 39-24. Shifting is a bit wider, but I didnt have any issues per se. The difference between the 11-21 and 11-23 simply isnt going to help you enough I dont think if the 11-21 wasnt working, and I dont think you'll need the 12-27 so you should be fine with a 12-25 - or even a custon jobber built up from an 11. The question becomes if you want to lose the 11t or not.

boudreaux said:

Since you aren't a top level pro,what does it matter what they use? I use what it takes to get the job done. Roberto Herras used a triple to win a stage in the Vuelta.

This is good advice. I forgot to comment on the original poster's other question about what the pros use. When you find out sometimes what the pros are using when they climb something ridiculous, you may reconsider your progress and fitness level lol, so I tend not to research what they use too often and simply use what is working for me. 😄

graf zeppelin said:

I'll take a stab at it and offer an opinion, but the simple fact that we're different riders using our bikes in different applications means take what I say with a grain of salt to be sure.

In terms of the effect a 12-27 is going to have on your wheel weight as opposed to an 11-21, you can effectively ignore it. More critical to the performance of your wheel would be the rotational weight, and the cassette is centrally located. Few extra grams on the overall wheel weight and overall bike weight, but its negligible unless you are at the highest end of fitness and every gram is critical.

I rode a 12-27 for two years and found myself in the 39-27 only on the mountains, and even then I tried to stay back in the 39-24. Shifting is a bit wider, but I didnt have any issues per se. The difference between the 11-21 and 11-23 simply isnt going to help you enough I dont think if the 11-21 wasnt working, and I dont think you'll need the 12-27 so you should be fine with a 12-25 - or even a custon jobber built up from an 11. The question becomes if you want to lose the 11t or not.

Thanks for the reply. Very helpful. I bought the 12/27 cassette because I wanted the option of the bigger gear if I needed it. I don't think there is anything worse then trying to get up a hill and wishing you had the bigger gear out back. Most of the triathlon courses here have some serious hills and I rode them last year on both the 11/21 and 12/25 cassettes. The 11/21 was too hard and the 12/25 was easier but I found that it was difficult to maintain the cadence when the grade got really steep. Did you go to a 12/25 after riding the 12/27 for two years and did that effect your performance in the mountains? Thanks again.

Peter Verdesi said:

Thanks for the reply. Very helpful. I bought the 12/27 cassette because I wanted the option of the bigger gear if I needed it. I don't think there is anything worse then trying to get up a hill and wishing you had the bigger gear out back. Most of the triathlon courses here have some serious hills and I rode them last year on both the 11/21 and 12/25 cassettes. The 11/21 was too hard and the 12/25 was easier but I found that it was difficult to maintain the cadence when the grade got really steep. Did you go to a 12/25 after riding the 12/27 for two years and did that effect your performance in the mountains? Thanks again.

I don't think there is anything wrong with a 12-27, the main downside is you have less gearing options in the middle gears. If you can ride hard across a wide range for cadence, then it shouldn't be a problem, but if you are like me and need to stay in a narrow cadence range, then jumping from the 21T cog to the 24T cog could pose a problem (the only differences between the 12/25 and the 12/27 is that the 24T replaces the 23T and the 27T replaces the 25T. See http://sheldonbrown.com/k7.html for more cassette info.)

Another option you might be able to pursue is if your small chainring is 42T, then you would do well to replace it with a 39T (which apparently requires a matching 53T big ring too). There is also the compact crank option, but that limits your top end speed and is more costly.

Also, if your abilities are improving every year, then you may be able to make it up the hill on the 25T before long.

Randybaker99 said:

Another option you might be able to pursue is if your small chainring is 42T, then you would do well to replace it with a 39T (which apparently requires a matching 53T big ring too). There is also the compact crank option, but that limits your top end speed and is more costly.

you don't need a 'matching 53' and there aren't that many thay can spin out a 50x12 except downhill.

Peter Verdesi said:

I live in the northeast of the United States (New York) and it's a bit hilly here and just had a question about the size of cassettes. I took up doing triathlons last year but have been riding almost my whole life (the riding I've been doing up until a couple of years ago has been more in a cross training capacity as running is my strongest skill). I'm building up a race bike for the up coming triathlon season and decided that, due to the hills in my area, a 12/27 cassette would be the best option. Last year I was riding a bike with an 11/21 cassette and found that I could not push the gear going up some of the steeper hills. I know that the 12/27 and 11/21 are at the extreme ends of the spectrum for cassette size but my question is this; is the 12/27 cassette too big? What do the pros use in hilly races? I have not taken the bike out yet with the 12/27 'cause it's too damm cold here but what should I expect. Does a larger cassette shift sloppily because the gears are further apart? I know that a larger cassette weighs more and that the weight on the wheel is important but does it really make that much of a difference? Thanks.

I use a 12-25t which fits with my short cage rear derailleur (something to consider as well). It gets me up all the hills that I've ever raced or trained on and I'm no climber by any stretch (I'm more like two climber..). I live in coastal Mass, but after spending a week in VT last summer, I would certainly consider a triple or at least a compact crankset with a 27 or 29t cassette if I lived in the mountains. Unless your a pro, I wouldn't worry about what they use too much. Boudreaux is corrrect, Heras used a triple to win the stage on the Angliru (26% grade) in the '02 Vuelta with Postal. ONCE decided to stick with the doubles, and he toasted them.
😎

PeterF said:

I use a 12-25t which fits with my short cage rear derailleur (something to consider as well). It gets me up all the hills that I've ever raced or trained on and I'm no climber by any stretch (I'm more like two climber..). I live in coastal Mass, but after spending a week in VT last summer, I would certainly consider a triple or at least a compact crankset with a 27 or 29t cassette if I lived in the mountains. Unless your a pro, I wouldn't worry about what they use too much. Boudreaux is corrrect, Heras used a triple to win the stage on the Angliru (26% grade) in the '02 Vuelta with Postal. ONCE decided to stick with the doubles, and he toasted them.
😎

Agree. I read Lance uses a 12-23 on most mountain stages, which of course means nothing to the rest of us. He's got over 550 watts of aerobic power to play with when he needs to put the hammer down on a long climb. I've got about 1/2 of his sustained power output...on a good day.

The hills he races up at a steady 14 mph have me down at a steady 6 mph....or less. So, about 1/2 his gear would be right for me to maintain a good climbing cadence.

It does come down to where you ride. VT is a lot different than Cape Cod, where a single-speed cruiser would be just the ticket.

PeterF said:

I use a 12-25t which fits with my short cage rear derailleur (something to consider as well).

A short cage shimano will work on a 30 and sometimes a 32 depending. A campy short cage is good for at least a 29. Long cage is about wrap capacity,not large cog.

boudreaux said:

you don't need a 'matching 53' and there aren't that many thay can spin out a 50x12 except downhill.

Well it is a fact that Shimano sells two 53T chainrings: A-53 is intended to be mated with a 42T inner ring and B-53 is intended to be mated with a 39T inner ring. Boudreaux, are you saying that there is no practical difference between them?

Peter Verdesi said:

Thanks for the reply. Very helpful. I bought the 12/27 cassette because I wanted the option of the bigger gear if I needed it. I don't think there is anything worse then trying to get up a hill and wishing you had the bigger gear out back. Most of the triathlon courses here have some serious hills and I rode them last year on both the 11/21 and 12/25 cassettes. The 11/21 was too hard and the 12/25 was easier but I found that it was difficult to maintain the cadence when the grade got really steep. Did you go to a 12/25 after riding the 12/27 for two years and did that effect your performance in the mountains? Thanks again.

12/27 is a fine choice. I suggested 12/25 thinking you hadnt been on a 12/25. Sounds like you have some pretty cool triathlon courses. Most I have seen arent terribly hilly. 12/27 will serve you well and you're probably not going to be missing the 11t all that much.

As regards my choices well, after two years on the 12/27 I was very happy with it honestly. Little reason to change. What changed was my fitness level. I was riding 300+ miles a week in mountains and dropped last year to more like 100+ miles a week on big hills. Life, work, you know. :p I moved my gruppo over to the training bike for the off season and built it up with an 11/23. Good for training, but I sure wouldnt take that setup on my larger gradient routes. This then raised a question of what to do with the main bike.

Since I prefer to climb with it - that's simply what I enjoy - settled on trying a compact 50/34 setup. Crunching the numbers made at least trying the compact attractive. With an 11/23 the range is surprisingly similar to the 12/27 with the 53/39. On days when the road really kicks up, a 12/25 affords even a bit more climbing assistance than the 12/27. Not new news to anyone who's looked at compact cranks. I didnt suggest it since it didnt make sense to me to use a compact for triathlons, but I could be wrong.

I agree with boudreaux in that, at least for me, I wont be spinning out a 50-12 gearing anyway and if I did ever feel I wanted to sprint (not my thing really lol), the 50-11 gives more top end than the 53-12 did. At least on paper. Wont have actual ride experience on it until May-ish. Staying on the training bike likely through April. Get that form back.

Best of luck with your triathlons. Should you, or anyone else, wish to play around with gearing numbers, this is fun:

http://www.soulbikes.com/gears/

I'm sorry I can remember where I found this link or who to credit, but someone in a forum somewhere posted it I think, and I bookmarked it. 😄

Gearing choices are a very personal and subjective thing. What works for you may not work for me or the next Joe Blow.

As others have said, it depends on your individual ability, the type of terrain you ride, whether you're more of a spinner or lean towards mashing, and so on.

IMO, very few people outside of higher-level pros really need or can ever use properly an 11T cog. If they think they need it, then they're just pumping their egos or their cadence is low, (usually it's the former). So, why not gain another gear in the midrange or low end where it's more useful, and toss the 11T?

I live in upstate NY near the Adirondacks and plenty of hilly/mountainous terrain, and I use 12-25 10v with 52-39 rings most of the time. I'm not a consistently high-RPM spinner, nor do I mash excessively, (somewhere in the middle I guess). However, I'm not one to normally do excessive amounts of climbing, but when I'm going to be climbing a lot, I'll use a 13-26 and a 38T small ring.

That suits my level of fitness and choice of terrain. If someone on a group ride can do the same grades with a higher or lower gear than me - that's their business. I don't ride their rig, I ride mine.

Randybaker99 said:

Well it is a fact that Shimano sells two 53T chainrings: A-53 is intended to be mated with a 42T inner ring and B-53 is intended to be mated with a 39T inner ring. Boudreaux, are you saying that there is no practical difference between them?

Exactly correctomento.

boudreaux said:

Exactly correctomento.

Fair enough, but I'll soon have an opportunity to put this to a test. I have been thinking about replacing the 42T ring on my winter bike and now Nashbar has 105 39T rings on sale for $14.95.