Road Cycling - choosing rear cassette size

I currently have a 12-25 which i am fine with and will be buying a new cassette soon, thee are so many options in sizes. Is there any rhyme or reason to choosing a size? 11-21 souns nice for speed and 12-26 good for climbing? i havea triple setup now. I am replacing the old one due to the fact that it's a well worn tiagra cassette now.

Since you have a triple, you must have had a very good reason to go with that setup initially. And since you're fine with the current 12-25, I'd stick to a similar replacement. You're definitely set up for some heavy duty climbing.

George

I have found very little use for an 11 tooth cog. I'd go 12-21 rather than 11-21. You will find the 18 tooth cog much more handy than the 11 which you probably won't use anyway.

If you are a cat2 racer or stronger then an 11 tooth cog is probably handy.

He who Spinsalot.

Look at what kind of riding your doing, and how you ride. I ride outside Boston which has rolling hills but nothing too serious. When I had my triple, I didn't use my granny, so the 25 was nice when I was lazy or really really tired. I found I could get away with riding the 42/12-13 in race situations, moving up to the 53 for sprints and attacks. But I prefer to ride high cadence (120+). I'd think that for riding with some serious hills a 12-25 would be fine if you're riding a triple. If you're racing look at what kind of races you do, if you do crits and get involved in bunch sprints the 11-21 comes in handy, plus you can ride the 42/11 pretty damned fast if you keep your cadence high and as bonus you'll have really smooth shifting since thats the closest thing to a straight block you can get for a 9-speed. Hell with the granny ring you can probably climb fine too. Personally, if you have a granny I'd think that having a 25+ is going a little over board as you're getting damned near a 1:1 ratio, max I'd go with is an 23 (I'm putting an 11-23 on my bike now and I ride a 53/39 now)...

well if that makes any sense ill be impressed

I went in the bike shop and was sold a triple, i dont know why, i guess the salesman didnt give a **** what i was getting as long as he sold me something. I will never buy a bike there again unless it is a once in a lifetime deal, i notice myself on the middle of the cog the most and sometimes i want a harder gear and i look back and i have no smaller gears left. Which is why i was looking at the 11-23. I love to climb so it's not a bad thing that thats what i ended up with (the triple i mean).

Unless you are serious race material or on a major downhill I doubt you will use the 11 very much.

i do find myself on the 12 needing more here and there. I will hopefully be racing next year.

Since you have a triple, my knee-jerk response would be to suggest going with the 11-21.

I'd suggest working out a gear inch chart for each of the prospective cassettes. Using your current setup as the baseline, see how many duplicate combinations each has, what you would be losing, and what you would be getting. That would be at least be an educated guess. There are several web pages that will calculate the gear inch combos for you. Any online catalog will supply the complete run-down of what gears come on each cassette.

I have a double so no comparision there but I was running a 12-25 and on more and more of my rides I needed a 11 and less and less of the 25. Actually I never used the 25 so I went with a 11-23. Best investment I ever made ;)

I'm working my way down the cassette category. I was running 12-27 (lots of hills). But now, I've switched to 12-23 to get the 16t cog---and still doing the same hilly rides. Finally got my butt into shape. It (the 16t cog) makes a difference to me.

The next step would be to consider an 11-23 or 11-21, but that won't be until I work myself into that kind of fitness level. My goal is to catch up to my friend and work out with him on intense group rides sometime next year.

I currently have a 12-25 which i am fine with and will be buying a new cassette soon, thee are so many options in sizes. Is there any rhyme or reason to choosing a size? 11-21 souns nice for speed and 12-26 good for climbing? i havea triple setup now. I am replacing the old one due to the fact that it's a well worn tiagra cassette now.

A useful tool for comparing various chainring/cassette cog ratios and combinations is a spreadsheet that I've used before. It has two gear ratio tables that allow up to 5 different chainring sizes to be entered and up to nine cassette cogs, for each table. There's an entry area for whatever cadence you would like to use and an entry for wheel circumference. Once you make your entries, it calculates gear ratios and the speed in mphs. for each chainring cog combination.

Measuring wheel circumference isn't complicated. Most people I've talked with use the chalk mark on the floor and simply roll the wheel once and make another chalk mark. A method considered more accurate (but will yield lower speeds and distances on your computer), is the dynamic version of the chalk mark. That is, the marks are made the same as before but with the rider mounted on the bike

If anyonne is interested I'd be happy to emnail the Excel file.
letmeknow: dacook@fedex.com

djbowen1,

I was in the same situation as you. I bought my bike with a triple and 12-25 setup. Since I don't do any hills on my normal rides, I never use my granny and 25 was way too big even in my middle ring (42). Like you, I was always in the middle on the rear cogs, so I wanted a 16, because jumping from 15 to 17 was a pain. 15 was a little too much and 17 was too easy. Anyway, going with the 12-23 was a world of difference.

I then thought I'd try an 11-21, since I don't have hill to climb, found that I never really got into my 11, so went back to the 12-23 and am a happy camper. I do slap the 12-25 back on when I know I'm going a ride that has big hills, but I mainly the 12-23 on all my rides.

I now have a new bike with a double. I had 12-25 on it, but swapped it for a 12-23 and am very happy with it. The next setup I'm gonna try will be 12-21, so I can have an 18! We'll see how that goes. :)

Well the gearing you use is profoundly influenced by your cadence.

I am a pretty high cadence cyclist and I like to sit and spin on hills so I like having lower gearing then most. Round here in Central Florida, I get by with a 13-25 9 speed. There are some 7% grades around here up to about .5 mile and a few spots that hit 10-14%.

My way of figuring gearing is what is the gear you need to climb up the hills you intend to climb? You go out and find what you need to climb your tough hill in the small ring and big cog. Easy. If you like to stand and do a low cadence, you can get by with a much smaller big cog.

The other is what kind of gear do you need at the top end? Well, just how much gear can you push? I have hit 38 mph in a 53X13 and I that is plenty of gear for me. So a 13 small cog is fine for my purposes. I would probably never use a 12 in the big ring.

Gearing is pretty much an individual taste sort of thing. Right now, with Lance Armstrong and his high cadence, more respect is paid to gear settups like mine. Of course, when the low cadence Lemond was in his prime, everyone wanted to push the biggest gears they could find. Really, it does not matter what is best for the top racer. What works for you is what is important.

I posted on this before...My bike was sold w/ a double up front and an 11-23 9sp in the back. As I'm just kind of getting back into biking, I immediately bought a 12-27, and have found it very satisfying. I realized that I was NEVER using the 12, so I swapped the 12 for a 16, and am now running 13-27. I'll do similarly on the smaller cassette and make it a 12-23, so that both cassettes have what someone called the "Magic 16." I can use that smaller one all winter (indoors) and hopefully be ready for it in the spring...saving the large one for big/super hilly rides.

Loving this set up now.

If you want the 11 so you can remain in the middle ring for longer, then maybe change your technique. Switch into the large ring earlier and shift up in the back.
There is nothing really bad about triples. For non competition use they make a lot of sense. If you ever take a tour into the mountains, you will see why.

If you only have one bike, it can make sense to use 2 sets of wheels. A training set for everyday, and a raceng set with closer ratios and higher gears.