louye2

The Shimano Hyperglide C cassette on my Trek 470 road bike is a bit worn. I would like to replace it, but I am not sure what tooth combination to choose. The original cassette is a 7 speed 11T - 24T. Between Nashbar, AEbike and other vendors, I have seen 12-32, 11-28, 13-26, 12-28, etc.

I do most of my riding on a paved 25 mile rail trail that is fairly flat with some small inclines. What cassette combination would you recommend for me?

Thank you.

Crankycrank

Depends on how happy you are with the current gearing. If you find that you need just a little bit lower gear for the climbing you do then go for a 26 or 28 lowest gear. If you are really struggling on the hills go for the 32. For the high gears if you find that you rarely or never use the 11t go for the 12 or 13. Obviously you're limited to the combos offered above but just use this post as a guideline. I believe your bike already has a long cage derailleur which can handle a 32 cog if needed.

Velocivixen

Hello @louye2 - Welcome! You've got a lot of choices and it will depend on many things. I'm somewhat new to the technicalities of gearing and such, but I'll throw out some questions and ideas.

Are you happy with the current setup in regard to your ability to go up hills (large cog) and your desire/ability to go really fast (small cog)? When you have 7 choices within a small range like you currently have (road cassette), there are smaller differences between each cog/gear, so as you shift you don't notice the changes as much. It's about keeping your cadence at an even rate, which road cyclists like. When you have 7 speeds within a wider range, there are usually larger jumps between each shift, especially as it nears the lower gears (bigger cogs). How often do you ride in your 11 cog? If not often, then I'd start with a 12 or 13 as my smallest cog.

I had this choice last spring and was trying to figure it out. I told the bike shop that my riding style doesn't have me in my high gear tearing down hills or straight always as fast as I can go, therefore they did not recomment I get a cassette with an 11 or 12 high gear - I'd never use it. However, I do have some hills I'd like to be able to go up with some help, but they're not super huge, so we didn't go with the 32 or 34 low gear, as I'd likely not need it for my type of riding. I like somewhat even spacing between shifts, but want more than 2 teeth difference between each cog - when I shift I at least want to be able to feel the difference. Anyway I think I went 12-30 or 13-28 or something in that range. I have a triple chain ring up front for reference.

Its also a good idea to buy a new chain with your cassette, as they wear together over time, so budget for that.

heres the bike in question:

Sorry the photos ended up in crazy positions. Not sure how that happened.

Drew Eckhardt 

13-19.

52x13 is a 45 MPH sprinting gear which is ample, and you don't want to waste your limited cog count on smaller cogs.

In the 8 speed era 13-21 was my favorite. For fairly flat I'd give up the 21 before the 18 which yields 13-19 seven cogs.

ThermionicScott 

The big thing is, as the others have pointed out -- do you use all of the gears? Do you ever wish you had higher or lower ones? The 11-24T is no longer available, but Origin8 makes an 11-23T, and there are wider and narrower options in 7-speed. I really like the 13-23T cassette on my main road bike.

louye2

Thank you very much for all your great advice. I seem to spend most of my time in the 12t - 18t range. So, I will probably opt for whatever cassette is still available in the 12t - 28t range. Looks like they are all about $20 - $30.

Is there any difference in quality between Shimano, Sram, Nashbar, etc.? What brands do you recommend? Thank you.

Bill Kapaun

Another, albeit more expensive, option is to buy 2 cassettes and mix & match cogs.
Back in my 7 speed days, I ran something like a 13-14-15-16-18-21-26.

ThermionicScott 

I've never used the SRAM or Nashbar or Origin8 cassettes, so hopefully someone else will chime in on them. The Shimano cassettes at least are serving me well, and I have yet to wear one out. At one time, Shimano made a 12-21 that would probably be perfect for you, but it seems like the dealers have run out of stock on that one.

Al1943

Selecting cassette gearing depends a lot on what size chainrings you have. As an example, both of my road bikes have 53 - 39 chainrings. They are a bit big for me so I compensate by running bigger cassettes, usually 13 - 26 although there are a few climbs in my area where I need a 13 - 29 (or a smaller chainring).

A good way to make gear selections is to check your cadence (crankset rpm). Empirical studies have found that experienced cyclists are more efficient riding in the 85 - 105 rpm cadence range. You don't have to spend a lot of money on a computer with cadence and it may be well worth it. Finding a cassette that helps keep you in that range throughout your ride can be a big help.

Andrew R Stewart 

I've always found that Shimano cogs seem to shift the best. Sram isn't too far behind. The house labels aren't stocked or sold by the shop I work at so can't say anything about them when new. But I do service bikes with the off brands and, since these bikes also usually have other drivetrain grade corners cut, their shifting suffers. Don't forget to replace the chain at the same time. here I do recommend SRAM. Andy.