Cassettes explained please

[Zippinalong]

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)?

Thanks!

[Zippinalong]

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

[KnottedYet]

Sheldon Brown (RIP) is always a good place to start: http://sheldonbrown.com/gloss_ca-g.html#cassette

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: http://forums.teamestrogen.com/showthread.php?t=44560

[OakLeaf]

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 parktool.com and sheldonbrown.com .

[radacrider]

+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.

[jobob]

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.

Yep.

[Zippinalong]

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 parktool.com and sheldonbrown.com .

I think my original statement in my post was obvious: But I don't know the first thing about cassettes and all of those gear ratios (mine is a 11-25T).
So I was looking for a basic explanation of what all those numbers meant. Also I was asking if they were easy to change out therefore getting an idea if it was something I could do or do I need my LBS to do it. Thanks.

[laura*]

I think my original statement in my post was obvious: But I don't know the first thing about cassettes and all of those gear ratios (mine is a 11-25T).
So I was looking for a basic explanation of what all those numbers meant.

In simplest terms, the numbers mean how many teeth are on the smallest and largest cogs. The fewer teeth on a cassette cog, the faster you'll go and the harder it will be to pedal. The more teeth, the easier it is to climb hills.

As the range smallest to largest increases, the bigger the jumps between gears will be. This means you sometimes might not have the perfect gear.

Also I was asking if they were easy to change out therefore getting an idea if it was something I could do or do I need my LBS to do it. Thanks.

Changing a cassette requires two special tools. However, this is a very basic thing for a shop to do. If you buy the cassette from them (and bring along the wheel), they might change the cassette for you for free.

[Sky King]

I am so lucky to have a DH who is a bike mechanic. I am not helpless but changing a cassette isn't on the top of my list. I told him about this thread and after his smart alec remark "isn't a cassette something you put music on in the 80's" he reminded me of the blog post he did about gearing so am sharing to you.

[laura*]

he reminded me of the blog post he did about gearing so am sharing to you.

In that blog post he says: "A gear inch is not a real unit of measure". Actually it is! It's the size of the equivalent front wheel of a penny farthing.

[SFLiz]

This thread is old but it's on topic for me as I'm swapping out my cassette from a 12-30 to a 11-28 because I'm upgrading my wheel set. I'm wondering if I'll feel the difference on my climbs. I am going to change the cassette because my bike (2013 Ruby Comp) came with an otherwise Ultegra group set except for the cassette (Specialized snuck in a Tiagra) and the front derailleur is a 105. Bastards. Anyhow, I went ahead and got an Ultegra cassette because I figured since I'm changing out my wheels, it's be easier and inexpensive to install a new cassette without having to remove the 12-30 off my DT Swiss wheels. Those could be my training set and I could leave the 12-30 cassette on them. Even though I won't need a chain whip this time, I might still get one for my bike tool box. I'm going to be doing this myself. There are some good you tube videos that explain quite clearly how to install a chainring. Seems straightforward. I'll be doing this as soon as I get my parts/tools tomorrow, including my bike stand to help with cleaning/lubing from now on.

Anyone think I'll perceive much change from 12-30 to 11-28? I do a fair share of climbing here in SF area. Thanks.

[indysteel]

How much of a difference you'll notice will depend on how often you currently use your 30 cog. If you don't use it much, then you likely won't notice it at all. If you use it a lot or some, then you might, but the gear difference between a 28 and a 30 is pretty small. However, if you already feel like you are running out of gears on your 12-30 setup, then the 11-28 is arguably not your best choice.

If you want to know the exact difference between the 30 and the 28 cogs, use Sheldon Brown's gear calculator.

[ridebikeme]

+1 on giving everyone more time to respond. The other thing that I would mention is that if you don't get answers as quickly as you'd like, perhaps you should check with your nearest bike shop.

Another thing that I would mention here is that unless your bike or current chain/cassette is fairly new, you may have to change your chain as well. Your chain and cassette mate together, and replacing one without other may cause serious problems.

I agree with others, that perhaps a bit more information about you, your riding habits, terrain would be helpful. Hopefully all of the responses have guided you in the right direction.

[indysteel]

+1 on giving everyone more time to respond. The other thing that I would mention is that if you don't get answers as quickly as you'd like, perhaps you should check with your nearest bike shop.

The OP in this thread (and the thread started some time ago) is the one that made a snarky comment about people not timely responding, not SFLiz.

[ridebikeme]

Indysteel, thanks for the clarification although I wasn't gearing this response to SFliz.