Maximum speed for a mountain bike

Got a general MTB question that doesn't fit anywhere else? Here's the place.
stanislavkostov
Posts: 3
Joined: Mon Oct 29, 2012 19:07 pm

Maximum speed for a mountain bike

Postby stanislavkostov » Mon Oct 29, 2012 19:17 pm

Hello, I have a question - if a Tour de France competitor rides an average mountain bike on a flat road how fast can he go and what average speed can he achieve?


Sorry if the post is in the wrong section.

User avatar
The Northern Monkey
Posts: 19547
Joined: Thu Jun 05, 2008 18:13 pm

Re: Maximum speed for a mountain bike

Postby The Northern Monkey » Mon Oct 29, 2012 19:31 pm

depends.

stanislavkostov
Posts: 3
Joined: Mon Oct 29, 2012 19:07 pm

Re: Maximum speed for a mountain bike

Postby stanislavkostov » Mon Oct 29, 2012 19:33 pm

On what?

paul.skibum
Posts: 3923
Joined: Wed Apr 22, 2009 16:46 pm

Re: Maximum speed for a mountain bike

Postby paul.skibum » Mon Oct 29, 2012 19:38 pm

gearing, wheel size, tyres, weight of the bike etc
Closet jockey wheel pimp whore.

paul.skibum
Posts: 3923
Joined: Wed Apr 22, 2009 16:46 pm

Re: Maximum speed for a mountain bike

Postby paul.skibum » Mon Oct 29, 2012 19:39 pm

Oh, and what drugs he's on!
Closet jockey wheel pimp whore.

User avatar
The Northern Monkey
Posts: 19547
Joined: Thu Jun 05, 2008 18:13 pm

Re: Maximum speed for a mountain bike

Postby The Northern Monkey » Mon Oct 29, 2012 19:40 pm

ha!

stanislavkostov
Posts: 3
Joined: Mon Oct 29, 2012 19:07 pm

Re: Maximum speed for a mountain bike

Postby stanislavkostov » Mon Oct 29, 2012 19:43 pm

I mean average bike, that you can buy in any supermarket, nothing special.

And no drugs

User avatar
The Northern Monkey
Posts: 19547
Joined: Thu Jun 05, 2008 18:13 pm

Re: Maximum speed for a mountain bike

Postby The Northern Monkey » Mon Oct 29, 2012 19:45 pm

btw, regarding forum, this would be best in the crudcatcher.

A general answer would be - probably not as fast as he would go on a road bike.

paul.skibum
Posts: 3923
Joined: Wed Apr 22, 2009 16:46 pm

Re: Maximum speed for a mountain bike

Postby paul.skibum » Mon Oct 29, 2012 19:48 pm

Google search got me this answer as I couldnt be bothered to do the maths myself:

For a gear ratio of 44:11 (front ring 44 tooth, rear cog 11 tooth), a speed of 32.7 mph on a mountain bike (tire diameter 26 inch) corresponds to a cadence (foot speed) of 105-106 rpm.

If you moved your feet faster :
120 rpm = 37.1 mph
150 rpm = 46.4 mph

Or if you changed your gearing (putting a larger ring on the front, for instance) ... for example, using a 48 tooth ring instead of the 44:
105 rpm = 35.6 mph
120 rpm = 40.4 mph
150 rpm = 50.6 mph

My personal best (over a distance of about a mile) is a cadence of 135 at a 44:11 gear ratio, which translates into 41.7 mph ... on low-profile knobbies (not true "mud" tires, but not road slicks either).


But I am suspicious now I re-read it that it is flawed.
Closet jockey wheel pimp whore.

paul.skibum
Posts: 3923
Joined: Wed Apr 22, 2009 16:46 pm

Re: Maximum speed for a mountain bike

Postby paul.skibum » Mon Oct 29, 2012 19:51 pm

I reckon 35 mph would be a good guess as a top speed on a 2" knobbly tired mtb with standard 9 speed triple gearing
Closet jockey wheel pimp whore.

User avatar
bennett_346
Posts: 5072
Joined: Mon May 03, 2010 09:47 am

Re: Maximum speed for a mountain bike

Postby bennett_346 » Mon Oct 29, 2012 19:52 pm

Why does it say that the tyre diameter is 26 inch?

Also it's just wrong, in every way.

User avatar
The Northern Monkey
Posts: 19547
Joined: Thu Jun 05, 2008 18:13 pm

Re: Maximum speed for a mountain bike

Postby The Northern Monkey » Mon Oct 29, 2012 19:54 pm

supermarket bikes only come with 7 or 8 speed though dont they?

User avatar
bennett_346
Posts: 5072
Joined: Mon May 03, 2010 09:47 am

Re: Maximum speed for a mountain bike

Postby bennett_346 » Mon Oct 29, 2012 20:00 pm

paul.skibum wrote:I reckon 35 mph would be a good guess as a top speed on a 2" knobbly tired mtb with standard 9 speed triple gearing

Why do the tyres matter?

Chunkers1980
Posts: 7909
Joined: Tue Feb 10, 2009 14:12 pm

Re: Maximum speed for a mountain bike

Postby Chunkers1980 » Mon Oct 29, 2012 20:28 pm

Are these serious questions?

User avatar
supersonic
Lives Here
Posts: 81829
Joined: Fri Nov 25, 2005 11:50 am

Re: Maximum speed for a mountain bike

Postby supersonic » Mon Oct 29, 2012 20:31 pm

Tyres matter because effective diameter influences overall gearing, and the type, tread and pressure influence rolling resistance depending on terrain.

Road bikes can be usually ridden faster on the road because the gearing is higher, and the air resistance and tyre resistance lower. But much can be done to even things out.

User avatar
bennett_346
Posts: 5072
Joined: Mon May 03, 2010 09:47 am

Re: Maximum speed for a mountain bike

Postby bennett_346 » Mon Oct 29, 2012 20:34 pm

supersonic wrote:Tyres matter because effective diameter influences overall gearing, and the type, tread and pressure influence rolling resistance depending on terrain.

Road bikes can be usually ridden faster on the road because the gearing is higher, and the air resistance and tyre resistance lower. But much can be done to even things out.

A tyre could have x amount of drag compared to another tyre but a more powerful rider could overcome this and add to the top speed, so the only limiting factor on a "supermarket bike" is the gear ratios.

Tyre diameter i'll give you but tread, volume and pressure do not matter, they simply increase the amount of energy needed to reach the top speed the gears will allow.

User avatar
supersonic
Lives Here
Posts: 81829
Joined: Fri Nov 25, 2005 11:50 am

Re: Maximum speed for a mountain bike

Postby supersonic » Mon Oct 29, 2012 20:36 pm

Which is what I was alluding to with comments on resistance. If you cannot output the power required then you'll be slower if there is more resistance ie unable to push a higher gear.

Stu Coops
Posts: 411
Joined: Sat Apr 09, 2011 14:01 pm

Re: Maximum speed for a mountain bike

Postby Stu Coops » Mon Oct 29, 2012 21:10 pm

All about legs and lungs
Zesty 514 Scott Scale 20 GT Expert HalfwayupMTB

User avatar
bennett_346
Posts: 5072
Joined: Mon May 03, 2010 09:47 am

Re: Maximum speed for a mountain bike

Postby bennett_346 » Mon Oct 29, 2012 22:02 pm

No it isn't. What utter garbage :roll:

User avatar
supersonic
Lives Here
Posts: 81829
Joined: Fri Nov 25, 2005 11:50 am

Re: Maximum speed for a mountain bike

Postby supersonic » Mon Oct 29, 2012 22:20 pm

cyd190468 wrote:Then why do they call them 26inch wheels? The outer diameter of the rim is about 22inches so a 2inch tyre round the outside makes 26inches. Please get out a tape measure before replying.


This is correct and is the reason the term was adapted - the nominal diameter of the wheel with tyre fitted. Started a long time ago, and the term has stuck.


Return to “MTB General”

Who is online

Users browsing this forum: No registered users and 4 guests