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Cassettes explained please

Zippinalong2011-12-31 01:14:33 +0000 #1
I saw another post on cassettes and that started me thinking that I don't know anything about cassettes! Someone was mentioning that they needed lower gears as they were finding hills a bit tough to climb. And I thought maybe that would be good for me too. But I don't know the first this about cassettes and all of those gear ratios (mine is a 11-25T).

Can someone please explain what all of that means and is it easy to swap out a cassette to get easier gearing (I'm sure within reason)?

Zippinalong2011-12-31 01:21:06 +0000 #2
Wow, 45 views and not one reply????
KnottedYet2011-12-31 01:50:39 +0000 #3
Sheldon Brown (RIP) is always a good place to start:

Each of the links in the brief overview are valuable, and you can spend hours reading his clear and well-written articles.

It was a huge loss when he died.

I've never changed out a cassette, so I have no experience to share with you there. But I've heard it's fairly easy and cheap to do, and some people do change them on a regular basis as they wear out.

This thread might be helpful, too: forums.teamestrogen....owthread.php?t=44560
OakLeaf2011-12-31 01:29:08 +0000 #4
You might give us longer than overnight ...

I think the hesitation is that it is pretty simple, but we're not really familiar with your degree of mechanical expertise or what other components are on your bike.

There are two special tools required for removing a cassette - a lockring remover, which is like a splined cylinder with a hex head, and a chain whip, which lets you hold the cogs so they don't spin while you're loosening the cassette. They're good things to have and know how to use anyway, since cassettes are a wear item that will need periodic replacement, plus you may well want to swap back and forth between two cassettes if you ride in different terrain.

I think any rear derailleur that will accommodate a 25T low cog will also accommodate a 27T and possibly a 28 (someone correct me if I'm wrong). If you want to go bigger than that, you probably will need to replace your rear derailleur with a longer-cage mountain bike derailleur. At a minimum, with any cassette change, you'll need to re-set the B-screw on your rear derailleur, and if you make more than a 3-4 tooth change in your big cog, you're likely to need a longer chain, too.

The short answer is there is no short answer with the information you've given us. How comfortable are you with tools? How much would you like to learn? How much do you trust your local bike shop?

There's a lot of really handy information on and .
Muirenn2011-12-31 02:48:21 +0000 #5

Originally Posted by Zippinalong

Wow, 45 views and not one reply????

Had it been a question about sunscreen, you'd have 46 replies with 45 views. But your question required an answer from someone that actually knew what they were talking about.

Personally, every time someone mentions cassette numbers, my eyes cross.
radacrider2011-12-31 02:46:12 +0000 #6
+1 to what the others have provided in terms of great on-line resources for information.

In addition to bike mechanicals for climbing you also have you. What is your climbing style? What is your current conditioning? Gearing that works for some may not work for your pedaling style. I tend to ride a lower cadence up the sustained climbs than when I am riding on more flat or short rolling terrain, so my bikes are set up with a bit higher gearing than if I only rode hills (not sure that even makes sense).

Also, what do you have for chainring set up? Double? Triple? Depending on your needs, you might need to do both, lower gearing (bigger rear cogs) on the cassette and a smaller smallest chainring on the front.



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