Gearing!

[Dibs]

I'm really happy with my bike - GT XC2 Aggressor - my only real complaint is lack of speed, once it's up to 20 odd MPH, when you pedal, it's like freewheelin' - what's the best way to sort this? Bigger rear sprocket?

Any help gratefully received!

 

[chillyuk]

A bigger rear sprocket will have you pedalling even faster! You either need a bigger front chainwheel or a smaller rear sprocket.

 

[Dibs]

Thanks. Of course I will! Got my head round that now! :-)

Can you buy these separately, or do you have to buy the whole thing?

 

[Alembicbassman]

I'm guessing it's got a compact MTB chainset on it.

The big rings at the front are something like 22 32 42 teeth, the rears are usually 11-32 teeth

You can change this to a 28 38 48 tooth set and keep the rear set.

New chainsets start from around £20 depending on the fitting. You may need to change the chain too which adds another £5-10

 

[RecordAceFromNew]

There are 3 possible solutions:

1) Count the number of teeth on the smallest cog at the back, if it isn't 11 then you are in luck because a new cassette with a 11T cog doesn't need to cost much and requires little effort and relatively simple tools to replace/fit. If the current smallest is 12T then you will get a ~9% increase in gearing. If your chain needs replacing then you could/should replace it at the same time.

2) Count the number of teeth on the largest cog up front. If it is 44T which is likely then as Alembicbassman said you can get another chainset that goes to e.g. 48T, which will add another ~9%. However chainsets are more expensive than cassettes generally and you will need to pick one that maintains the chainline so that it doesn't have knock-on effects on your front shifting. You will probably need a longer chain and you might have to change the bottom bracket to maintain the chainline.

3) Spin faster. I am no expert and there are plenty of references on the web but around 90rpm is often quoted as a good average cadence for most people to aim for and that a relatively high cadence is helpful in exercising one's cadiovascular system. Even with a 44/12 you should hit just over 25mph with 90rpm at the pedals.

 

[mickle]

'Spin faster' is the best answer.

The thing is, when we get on a bike we tend to pedal at a rate with which we are familiar, and as a biped mammal we are familiar with a 'steps per minute' rate which is way too low for riding a bike.

Watch regular, experienced cyclists and they spin away at high RPM when compared to less experienced cyclists.

 

[Nebulous]

I always cranked away in my highest gear most of the time on my mtb, and also I tend to walk with big paces. After getting a road bike I've made a determined effort to increase my cadence and spin much faster now. However I find when I'm out walking I'm taking shorter paces!

I had a colleague many years ago who used to say 'beware of men with small steps' he also used to say 'I don't trust him, he takes too small steps.' I never quite worked out why, and I hadn't thought about him for years, but thinking about the changes that cycling is bringing to me brought all those memories back!

 

[Archie_tect]

'Spin faster' is the best answer.

Can't remember where I heard it but pedalling to the rhythm of BeeGee's 'Staying Alive' humming around in your head works at 90rpm, but don't forget to breathe.