MTB vs Road bike Cassettes: What's the difference?

[SimonR]

I'm just ordering a few last bits for my new road bike and can't see how road bikes' cassettes differ from MTB ones.

I know that I want a 11 tooth smallest ring and anything up to about 30 is fine at the other end (I'm not too bothered about the low gears as Cambridgeshire is so flat).

I saw this and it looks OK but I'm unsure if it's right for my road bike... I've checked a couple of on-line shops but their cassettes seem rather pricey.

Any ideas?! - Cheers

 

[Steve Austin]

No difference at all.

Lots of DH mtb riders use close ratio roadblocks
and you get MTB cassettes on cyclocross bikes to give a larger spread of gears

The only concern with fitting a MTB block to a roadbike is your dérailleur 'might' not be able to accommodate that larger range of gears. What rear mech has you bike got?

 

[Tynan]

a 30 for flat?

 

[nuovo_record]

simon - you won't need a 30 for cambridge. i go out to elmdon and chrishall and i can go up them with a 53 - 19 combo....11 for the smallest might be too small, try a 12 or 13 to 23

 

[Sittingduck]

12-23 or 12-25 would be good enough for the flatlands I think
Like Steve said, if you try putting a XX-30 the rear mech might not be able to handle it.

Tiagra 8 speed cassettes for 22 quid here

SD

 

[andrew_s]

The cassettes are interchangeable, but many road bike cassettes are 10-speed, whilst MTB are still 9-speed. If you get 10-speed STI, you're stuck with road cassettes (27T max)

Road rear mechs nominally go up to 28T. 30T is usually possible with a bit of fiddling, but at 32T the mech top jockey hits the big sprocket. If you want to be able to slot on an MTB cassette, you'll need an MTB rear mech. These won't shift as positively on a smaller road cassette (11-23 or whatever) as a road mech would.

Fewer speeds means cheaper parts, so whilst 8-speed cassettes start at about £18-20, 10-speed start at £35-£40. The downside is less choice and being limited to the lower end of the groupset hierarchy. For 8-speed shifters, there's the Sora, and the non-groupset R500 (about 105 quality).

 

[simon_brooke]

You can't use a Campag cassette on a mountain bike hub; SRAM and Shimano cassettes are compatible with one another but Campag are different (Campag cassettes go up to a maximum of 29 teeth but this is irrelevant because you can't use them). Also, nine and ten speed cassettes have different spacing, so won't work with eight speed indexing. Details here.

The newest mountain bike groupset from SRAM (XX) has a ten speed 'power dome' (one piece cassette) and a double chainset, but it's shedloads of money and only out for the pros so far.

 

[nuovo_record]

simon has bought some shimano compatible wheels, but he has d/t levers unless i am mistaken so he only wants 8 speed.

 

[SimonR]

Thanks for all those replies gentlemen and apologies that it's taken me a little while to get back onto this thread!

There's some really useful replies below so I took it all into account and bought an 8-speed cassette for my Shimano-compatible new wheels. As Nuovo_Record says above - I'm going with my down-tube shifters and therefore 8-speed is my only real option.

I've bought a Shimano-compatible cassette with the following cogs: 11, 12, 14, 16, 21, 24, 28 - maybe it'll not be quite right for my intended purpose but with a 48 tooth front ring, 11 at the back will perhaps be about right. Anyway, it was only a cheapie so I can work out what I need and buy the proper Shimano item later on.

I've also bought a KMC 8-speed chain so hopefully it'll be shifting nicely!

With refard to the rear derailleur, it's an old Sun Tour one from 1984 - not very much wear and it seems to have the right amount of movement for this cassette so I'll wait and see.

The front derailleur could be more problematic though - I thought I had two Sun Tour ones to choose from, but one's very badly worn and the other appears to be seized! I think replacement may be the only option for me so I'll be looking at Shimano's offerings online later on.

I'm looking for lightweight and sub £40 - any suggestions anyone?

Many thanks to all for your continuing help - hopefully my wheels arrive this evening - can't wait ;-)

 

[simon_brooke]

The front derailleur could be more problematic though - I thought I had two Sun Tour ones to choose from, but one's very badly worn and the other appears to be seized! I think replacement may be the only option for me so I'll be looking at Shimano's offerings online later on.

I'm looking for lightweight and sub £40 - any suggestions anyone?

Many thanks to all for your continuing help - hopefully my wheels arrive this evening - can't wait ;-)

Do you know your downtube diameter? Also, do you need a downtube clamp, or is their a braze-on, or one of those bottom-bracket front mech mounts? Finally, does the cable come in from the top or the bottom?

Broadly front derailleurs are not that sensitive - it should ideally follow the curve of your largest chainring, but it doesn't seem to matter that much. So provided it will physically fit and take the cable from the right direction it will probably work. Obviously one which fits your chainset precisely will work better.

 

[nuovo_record]

Do you know your downtube diameter? Also, do you need a downtube clamp, or is their a braze-on, or one of those bottom-bracket front mech mounts? Finally, does the cable come in from the top or the bottom?

Broadly front derailleurs are not that sensitive - it should ideally follow the curve of your largest chainring, but it doesn't seem to matter that much. So provided it will physically fit and take the cable from the right direction it will probably work. Obviously one which fits your chainset precisely will work better.

guessing at 28.6, band-on, bottom pull!

 

[SimonR]

guessing at 28.6, band-on, bottom pull!

Yeah - I should have specified that!

You're right with the above info though.

I'll take a look on the web tomorrow and see what there is available.

The wheels came today and although my girlfriend says they look a bit 'gay' I really like them!

 

[SimonR]

One other thing - does it matter that some front derailleurs are specified for 9 or 10 speed cassettes, but I'm only using an 8 speed one?