# Why can't I get the right gearing????



## TrugMaker (30 Dec 2012)

I have tried and tried to find someone who can suggest a way to have road gearing on my mountain bike! When I am on the flat (perhaps slightly downhill) my legs are going like a fiddlers elbow and I really am not going more than 18 MPH. My front cog is 48 - rear 11. SURELY one can fit a road front cog, I have no swing arm frame to complicate the issue. I have never ever had to use the other two smaller front cogs, nor the very lowest gears on the large cog. I know you will say "buy a road bike, but most/all of my riding is on dirt and muddy trails. But I do have the 'need for speed' often


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## PpPete (30 Dec 2012)

48 x 11 @ 18 mph is .... 60 rpm
Fiddler's elbow it ain't.

A respectable spin speed of 100 rpm in that gear takes you to 30 mph, at which point most of us start to think about freewheeling anyway.

But, if you want to, fit a road chainset, move your front mech up the seat post a few mm, and enjoy !


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## lulubel (30 Dec 2012)

A road bike chainset isn't going to make that much difference. My road triple only has 50 teeth on the big ring.


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## oliver (30 Dec 2012)

PpPete said:


> 48 x 11 @ 18 mph is .... 60 rpm
> Fiddler's elbow it ain't.


+ 1 
regularly keep a steady 30mph+ on the flat with a 44 x 11


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## Rob500 (30 Dec 2012)

PpPete said:


> 48 x 11 @ 18 mph is .... 60 rpm
> Fiddler's elbow it ain't.


 
More like Tennis Elbow.


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## Rob500 (30 Dec 2012)

Nah, only kidding TrugMaker. Welcome to the forum.


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## Cycleops (30 Dec 2012)

Try a 52 front ring but it's not going to make that much difference.


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## TrugMaker (31 Dec 2012)

Thankyou all, really didn't expect a response at all. Have just recently discovered the joys of cycling, in my area there are so many woodland and country rides but there are times when I just need to speed (the reason I no longer drive a car). But my wife bought me a fantastic stereo that sits on the handlebars (as I think headphones are dangerous), I think the accompanying music will alleviate that urge after removing the Heavy Metal tracks!


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## 02GF74 (31 Dec 2012)

PpPete said:


> 48 x 11 @ 18 mph is .... 60 rpm
> Fiddler's elbow it ain't.
> 
> A respectable spin speed of 100 rpm in that gear takes you to 30 mph,


 
the big ring on most mtb is typically 42T ot 44T. If you can spin at 100 rpm - assuming above is correct - which sees you doing 30 mph on the *flat* on an mtb with fat tyres, then you must be approaching super human status.... which I find somewhat hard to believe - that would be equivalent to 35 mph on road.

If you are talking about spinning out on downhills, then fitting larger ring will help but it will compromise gearing for off road riding. You may need to raise the front mech and may have trouble when shifted to the smallest chain ring as you have exceededed the capacity of the front mech.


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## lulubel (31 Dec 2012)

02GF74 said:


> You may need to raise the front mech and may have trouble when shifted to the smallest chain ring as you have exceededed the capacity of the front mech.


 
I was going to ask about that. My understanding was that road and MTB chainsets, front mechs and shifters are not compatible - at least not Shimano ones. If you want to change the chainset, you need a new front mech and shifters as well. Is that correct, or am I way off the mark here?


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## PpPete (31 Dec 2012)

Certainly there is a lack of compatibility between road and MTB as far the shifters & mechs are concerned (they use different cable pull amounts)
but both MTB and road mechs will usually operate the intermediate sized chainsets that are produced for hybrids and touring.Thus road mechs designed for 52/39/30 may struggle with MTB chainsets like 42/32/22 (and vice-versa) but both are probably OK with 48/38/26 even though the curvature of the mech cage may be less than ideal.


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## PpPete (31 Dec 2012)

Cycleops said:


> Try a 52 front ring but it's not going to make that much difference.


 
Unfortunately most MTB chainsets are 4 arm, whereas nearly all 52 rings are for 5 arm. Let alone the various different BCDs (bolt circle diameter).


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## lukesdad (31 Dec 2012)

PpPete said:


> Unfortunately most MTB chainsets are 4 arm, whereas nearly all 52 rings are for 5 arm. Let alone the various different BCDs (bolt circle diameter).


 Older mtb chainsets are 5 arm with same BCD as modern compact chainsets, If its a square drive BB you can pick them up cheap as chips on fleabay.


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## lulubel (31 Dec 2012)

PpPete said:


> Thus road mechs designed for 52/39/30 may struggle with MTB chainsets like 42/32/22 (and vice-versa) but both are probably OK with 48/38/26 even though the curvature of the mech cage may be less than ideal.


 
That's useful, thanks. I'd rejected my original idea of putting a 48/38/26 on my Surly for touring because I thought it would be incompatible and I'd have to give up my STI levers. It would be very nice if that isn't the case.


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## CopperCyclist (31 Dec 2012)

PpPete said:


> 48 x 11 @ 18 mph is .... 60 rpm
> Fiddler's elbow it ain't.
> 
> A respectable spin speed of 100 rpm in that gear takes you to 30 mph, at which point most of us start to think about freewheeling anyway.
> ...



+1

What you're thinking of as pedalling fast, isn't. Take Petes suggestion, find a downhill and get those legs spinning until you are doing 30mph or so!

It may help you acheive this if you try to improve your overall cadence - I.e. start dropping down a gear on the flat, but thm pedal faster to maintain the same speed - sounds like you might be to used to grinding out too big a gear if you see 60rpm as pedalling fast!


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## PpPete (31 Dec 2012)

Or if there is a gym near you with a spin class, try it out for a few weeks. Apart from anything else the, er, "scenery" is usually worth it.
My "relaxed" pace on the road has been in the 90-100 range for a long time but I really struggled to get beyond 120 at the beginning. Now I can hold 140 for a full track and "burst" to 165 for short periods.
No doubt if I'd taken this up before my sixth century I might be hitting 180s by now


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## RecordAceFromNew (31 Dec 2012)

PpPete said:


> Certainly there is a lack of compatibility between road and MTB as far the shifters & mechs are concerned (they use different cable pull amounts)
> but both MTB and road mechs will usually operate the intermediate sized chainsets that are produced for hybrids and touring.Thus road mechs designed for 52/39/30 may struggle with MTB chainsets like 42/32/22 (and vice-versa) but both are probably OK with 48/38/26 even though the curvature of the mech cage may be less than ideal.


 
+1.

It is also worth watching out (and prepare) for chainline incompatibility if mixing and matching - Shimano road triple and mtb triple chainsets (and therefore associated front mechs) generally are not designed to operate with the same chainline so one can run out of reach inboard or outboard. Road 45mm, mtb 47.5mm or 50mm.


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