Changing Gearing on my MTB

Newfish

Hello All and sundry,

I was wondering if someone could help as I haven't had a satisfactory answer from the 3 bike shops I have been into.

I am trying to get a bit fitter and have just bought a Specialized Rockhopper, a bike I have wanted for many many years. It will predominately be for off road use, however, I would also like to set it up for road use. At the moment I don't want to fork out for a road bike so that isn't an option. I have two questions, which I'm sure will throw up lots more issues.

Firstly, due to the off road gearing that it came with I find, even with the huge knobbly tyres, that I run out of gears when going downhill, or even on some flat sections, what I would like to do is add a harder gear. Either by changing the 44T on the chainset to a 53 (or whichever is best) or by changing the cassette (see question 2).
What I would like to know is this. Is it possible to remove the smallest chainring from the chainset and put what is currently my middle chainring in its place, then put a 44T ring in the middle and a 53 on the outside? The reason I would like to do this is so that I still have the low gearing for off road use but have the higher gearing for road use. I never use the smallest chainring so don't mind getting rid of it.

Secondly, I would like to get a set of road tyres/rims set up for days when I want to go road cycling, being lazy I would prefer to have a full set of rims for road use, and then the ones I currently have for off road. This might mean that the cassette I have on the rear rim could be more road orientated, however, and I am probably wrong, I couldn't find a cassette that had smaller than an 11 tooth. (is there?) My question is this, what information do I need to get off my frame (measurements) to order the correct rims?

This is what I think I need;

Axle length (from inside to inside of the frame)
disc size/diameter
Wheels are 26" - I know that much.
Is there a limit to how narrow I can go on the rim to fit the frame I have?
Best suited cassette for road use, bearing in mind question 1.

Or is this all just a waste of time and should I just get some simple road tyres and save up to get a road bike?

Thanks in advance for any and all comments.

PS - are there any cycling groups/clubs in the Solihull area, and I don't mean full lycra clad road warriors.

PPS - I'm new and this is my first post so please bear with me.

nicklouse

bigger outer ring. about 48 is the biggest you can go. but your mech might not manage.

nothing smaller than 11T yet.

cost of wheels tyres tube cassette disc will be the same as a road bike.

either buy some slicks and tubes and change them over or buy a road bike.

Chunkers1980

Just buy some slick tyres and change as required. Oh and pedal faster.

supersonic

How fast are you actually going? 44-11 gear at 120rpm is nigh on 40mph!

Newfish

nicklouse wrote:

bigger outer ring. about 48 is the biggest you can go. but your mech might not manage.

nothing smaller than 11T yet.

cost of wheels tyres tube cassette disc will be the same as a road bike.

either buy some slicks and tubes and change them over or buy a road bike.

Thanks for the quick replies gents.

I was told that a new set of rims would be about £150. I'll double check tomorrow what the outer ring is, I think its a 44, but maybe not. When you say the mech wont manage, what exactly do you mean? Whats stopping me putting something bigger on? Chain length/derailleur?

Supersonic - 40mph!! haha, I wish, which makes me think the outer ring maybe less, I topped out at 32 the other day, peddle any faster and it would have been uncomfortable.

nicklouse

1 finding something that will fit.
2 the max that the mech will take 44 or 48.
3 you will need to resize the chain anyway.

I was told that a new set of rims would be about £150.

wheels maybe, add tryres, tubes, rim tape. discs and a cassette. and then resetting the calipers each time you change over.

WindyG

I was in the same position as you and as above, once you add the costs up you might as well save a bit of money up and get a road bike it was what I did.

bikaholic

If purchasing a new crankset and/or a new cassette is an option then the following will work:

1. Compact double 50/34T, 110BCD - (will work with 11-32T, 11-25T etc cassettes);
2. Standard double 52/39T, 130BCD - (will work with 11-30T max cassettes, ie biggest cog should be as small as possible).

But, they must be of the square taper, Octalink or ISIS variety where you have some control over the spindle length, hence, chainline.

Standard Shimano MTN FDs will handle the compact double and Shimano R-series FDs (eg FD-R440) will handle the standard double.

cooldad

Which, if it works, will make it horrible and useless off road.

nicklouse

bikaholic wrote:

Standard Shimano MTN FDs will handle the compact double and Shimano R-series FDs (eg FD-R440) will handle the standard double.

sure if you start bending cages.

bikaholic

nicklouse wrote:

bikaholic wrote:

Standard Shimano MTN FDs will handle the compact double and Shimano R-series FDs (eg FD-R440) will handle the standard double.

sure if you start bending cages.

No bending of cages necessary.

The specs that Shimano states for the components are optimal values, and, as it turns out, are quite conservative values.

But, you will need to have encountered numerous combinations in order to see what will and what will definitely not work.

supersonic

Depend how optimum you want your shifting. It drops off very quick.

Newfish

Thanks for all the replies. It sounds as though a road bike might be the way forward then. Damn.

YeehaaMcgee

Newfish wrote:

Thanks for all the replies. It sounds as though a road bike might be the way forward then. Damn.

Yeah, road bikes are best for road. Shocking news. :roll:

njee20

1. Compact double 50/34T, 110BCD - (will work with 11-32T, 11-25T etc cassettes);
2. Standard double 52/39T, 130BCD - (will work with 11-30T max cassettes, ie biggest cog should be as small as possible).

Huh? You can run an 11-36 with 53/39 if you want.

However, it's not worth going down that avenue IMO, as others have said. Get some slicks to tide you over, get used to pedalling faster - 32mph is barely over 100rpm, which isn't that quick, then save for a road bike.

bikaholic

Err, it has nothing to do with capacity if thats what you're getting at - more to do with chainline.

If chainline is at borderline working limit, then running a very big chainring (ie 53T) with a very big cog (ie 36T) will cause the chain to drop down onto a smaller cog when you back-pedal. Hence, why you should try to keep it as small as possible.

YeehaaMcgee

I don't see how, since the centre of the cassette and the centre of the chainring along the length of the bike (the point at which the chain makes initial contact) remains unchanged.
Not only that, but they're the same distance out from the bike's centreline.

njee20

Works for David Millar - the Osymetric rings meant he couldn't go compact, so just fitted an XX mech and cassette for the Giro last year, so he had a 53-36 potentially. He didn't die. Big/big isn't a good idea irrespective of chainring size, as you'll know.

YeehaaMcgee

njee20 wrote:

Works for David Millar - the Osymetric rings meant he couldn't go compact

Did you know they're called that, because they're awesome, and metric, but the marketing department couldn't spell?

bikaholic

njee20 wrote:

Works for David Millar - the Osymetric rings meant he couldn't go compact, so just fitted an XX mech and cassette for the Giro last year, so he had a 53-36 potentially. He didn't die. Big/big isn't a good idea irrespective of chainring size, as you'll know.

And your point?

Have you forgotten the OP's original intention?

Reminder: O.L.D. 130mm, O.L.D. 135mm.

supersonic

The larger OLD of the Hopper might give a better chainline for that gear combo though! We don't know the figures... at least not to hand: as with a lot of things in this thread, might have to experiment.

bikaholic

supersonic wrote:

The larger OLD of the Hopper might give a better chainline for that gear combo though!

But will the chainset still clear the chainstay and be in range of the FD?

Build one up and see.

supersonic

That's sort of my point. It has to be experimented with, and only yourself knows what you are willing to put up with with regards to shifting.

Chunkers1980

It's all pointless anyway. Refer to my first post.

bikaholic

supersonic wrote:

That's sort of my point. It has to be experimented with, and only yourself knows what you are willing to put up with with regards to shifting.

No, you misunderstood.

Build one up and see that I am right in what I stated.

Chunkers1980

Who cares? It is a stupid idea. Buy the correct bike

supersonic

bikaholic wrote:

supersonic wrote:

That's sort of my point. It has to be experimented with, and only yourself knows what you are willing to put up with with regards to shifting.

No, you misunderstood.

Build one up and see that I am right in what I stated.

Explain then. I am not sure what you have stated, you need to be clearer. You mentioned the OLD, and only that, in response to the road bike.

Newfish

Chunkers1980 wrote:

Who cares? It is a stupid idea. Buy the correct bike

I think 'stupid idea' is a bit harsh, it was merely a question to see if it was a feasible option. Many things have changed since I last rode a bike and for all I knew someone could have come back and said, 'get a new set of rims and get a 8-32 cassette. As it happens 11 is the smallest that is made, which is what I have, so the only way to do what I was wondering would be to put a bigger top ring on, this isn't practical. So the outcome is, get some slicks for road use, peddle faster ( ) and save up for a road bike.

Just out of interest though, what does 'chain line' mean, also, is there anything that I should look out for on my Hopper that is a weak point? Gears/Shocks/brakes etc? The bike spec is;

Specialize Rockhopper 2012 with;

Brakes - Tecktro Draco hydro discs
Gears - Acera Mega drive (?)
Tyres - The captain Sport 26x2.5
Rims - Alexrims RH (might be 12H)
Shocks - Suntour SR XCR

Thanks for all the input gets, much appreciated, especially since it was my first post.

supersonic

Some good info here:

http://sheldonbrown.com/chainline.html

Chunkers1980

A bit harsh but fair.

You can get smaller than 11t. SRAM now have 10-42 cassette and Hope are doing a 9t. But yes 11 is smallest with a standard free hub.

njee20

You can get smaller than 11t. SRAM now have 10-42 cassette and Hope are doing a 9t. But yes 11 is smallest with a standard free hub.

There's also Shimano Capreo, which has a 9t. XX1 only works 1x11, costs a fortune and requires a DT/SRAM hub. The Hope is firmly in the vaporware category. To all intents and purposes there's no practical solution (in this instance) smaller than an 11t.

Build one up and see that I am right in what I stated.

You're not though are you, you can run bigger than a 52-30 just fine. Why would you be pedalling backwards in that gear combination anyway?