Help me choose a 7-sp cassette please

krushgroove

I have converted an old 21-speed mountain bike to commuter duty, and with summer here I have found out a couple of mates in town have mountain bikes, so I want to be able to dual-duty my bike. To this end, I bought a set of wheels off eBay but since there wasn't a picture of the complete wheels I didn't notice the text mentioned nothing about a cassette/freewheel NOT being included, so now I have to get one of those as well...

...this isn't so bad, though, because I can keep the original rear wheel in the off-road set, and purchase a rear cassette especially suited to commuting!

However, I'm not great at figuring out gear ratios and all so I need a bit of help if you don't mind.

There's a big range of 7-sp cassettes available still, thankfully, but I'm not sure what teeth numbers I should get. As I understand it, a lower number on the small cog will give me more top speed, and these range from 11-14 teeth; and if I'm correct a higher number on the large cog will let me climb easier (???), and these range from 28-32 that I've seen. Is that correct? The off-road cassette I am using right now suits me fine, I use all three front chainrings going both ways to work, and on the one big hill I encounter I'm in the lowest gear possible for the climb (although I'm hoping the time I use that gear will lessen as I get fitter). Unfortunately I didn't ride in today so I can't tell you what the teeth counts are right now...

I don't really want to change to an 8-sp cassette or drop to 2 chainrings on the front, I've already spent enough money in gear and tat and just want to optimize the commuting speed/experience for the price of a new or used cassette Plus I can't have another bike, no money and no space!

I don't know at the moment the number of teeth on my chainring, but this shouldn't matter (I hope?) since the bike will be doing off- and on-road duties.

I hope this is enough info for you all, and I'd appreciate any help!

Gussio

How about this: http://www.wiggle.co.uk/ProductDetail.a ... 20Cassette

If you have a 44/32/22 chainset, the 11-28 cassette should be pretty good for communting.

Not sure what to suggest re: chain. If your existing chain and cassette are have worn in together, then skipping might be an issue when you change between rear wheels. It would be a minor drag, but you could think about buying a lockring tool and chain whip to swop the cassette between wheels (i.e. not buy a new cassette at all)?

krushgroove

Thanks very much for the reply! Hmmm yeah I forgot about the chain...

I actually had to look up what a chain whip is, didn't realize I'd need to get yet another tool to put the cassette on! I wouldn't mind swapping the chain if I have to (I don't anticipate doing loads of off-road action), that way I have something that fits the particular cassette - just pop the installed chain into a sealed plastic bag, put the new one one, take the other one out of its bag and pop it on...does that sound more feasible, or is that more work than changing the cassette? Hopefully the chain will fit both cassettes and this isn't even an issue


Back to the cassette size though, my commute is quite hilly through many of the suburban areas I go through, as well as the country lanes, would the 11-28 combo in general be alright with that sort of terrain?

Gussio

krushgroove wrote:

would the 11-28 combo in general be alright with that sort of terrain?

Depends how strong your legs are

re: chain, that might work if you bought a chain that has a snaplink like some of the KMC ones...

krushgroove

Gussio wrote:

krushgroove wrote:

would the 11-28 combo in general be alright with that sort of terrain?

Depends how strong your legs are

re: chain, that might work if you bought a chain that has a snaplink like some of the KMC ones...

Hopefully I'll be alright I'll check how the chain fits first and see if I have to do anything

Thanks for the help!