Cassette Size

morxy

I want to make my Scott Sub 20 a little faster.

LBS says I should try a smaller cassette. He handed me an 8 speed Shimano 12-25 cassette. However, I've seen 12-23 and 12-21 8 speed cassettes on other sites. Would they be faster? All we're talking about is reducing the number of teeth on the larger sprockets (lower gears), right? Wouldn't that make initial acceleration a touch slower though?

Any advice?

Steve Austin

Changing cassette will have no effect on top speed. You need a bigger ring up front, but then again Eddy turned smaller gears than you got and he was fast

John C.

The only thing that will make you faster is if you peddle faster. If you don't ride up any hills then by all means do away with your big rings on the back and you may well prefer the closer mached gears but it won't make you a faster rider. Sorry

cougie

As Lance says - its not about the bike.

Although - what tyres do you have on it ? Slicks will roll better and if you can fit narrower tyres - so much the better.

A track pump will inflate the tyres to 100PSI with ease - so that will help.

Clipless pedals will let you put a bit more power into each stroke.

Oh and get an aero hat too. 8)

Rykard

What size cassette do you currently have? If you go to an 11-23 that would be quicker but if your are already spinning out on a 12-?? then another 12-25 or 23 will make no difference.

morxy

Thanks for the advice everyone.

Currently my cassette is 11-30T, 8 speed. (That's a big biggest ring isn't it?). Tyre wise, I ride 26" x 1.25" Maxxis Columbiere slicks at about 90psi.

Rykard

If you're already on an 11 then the only way is a larger chain ring...

Rich

cougie

Well you have a 48tooth chainring on there anyway, so you could get a bigger one.

I dont think the problem is with the bike though - its with the way you are riding. a 48*11 is almost enough for a 40mph TdF bunch finish.

You need to learn to spin the gears faster.

How many pedal revs do you do in a minute ? It should be anywhere from 80-100 ? I bet you're only doing about 60 ?

bigdawg

dont go nuts on the gearing, youll end up not being able to ride up hills...

What gear are you normally riding in, unless youre in top gear all the time your gears are fine.

Cadence is your friend, as said above.

Rykard

Also if you change the front rings, you may have to change your front derailleur, and possibly the chain.

I would echo as above, see if you can up the cadence. I ride a slick shod MTB with 42/32/22 x 11-28 i think?? and spinning out downhill is about 35mph...

Monty Dog

As said, It's proably the 'engine' that needs the work rather than just changing your cassette. If you're not using clipless pedals and propoer bike shoes, they will make a big difference to getting the power down and developing a more efficient pedal stroke where you apply power consistently through the stroke, rather than just 'pushing'. To go faster you need to develop a smooth pedalling action, probably one that's faster too. The only other thing you might consider with the bike is removing any excess weight e.g. locks, lights, racks etc if not needed. You could also run narrower tyres - you can get 1" tyres - but they are more prone to punctures. Fitting a bigger chainring will probably mean a whole new chainset as well - 48x11 should be easily good enough for 50kph - how fast do you want to go?

nun

Getting a closer ratio cassette might help you feel a bit more comfortable, but it won't improve your speed, training on whatever you've got now will do that. I think that most people over gear their bikes anyway and their top gears are only useful on downhills. My top gear is a 42x11 which will take me up to 24mph at 80rpm. If you can do 24mph at 80rpm for an extended period you need bigger gears, if you carn't then why bother unless you're racing downhill.