What's the likely speed conversion: mtn / road bike?

Fatamorgana

If you assume the two bikes are roughly equal in terms of kit, tyres etc, what's the likely conversion in terms of speed on the road going from a mtn bike at say an average of 14mph (on a 3hr ride) when moving to a road bike? I'm told it's about 5mph faster on a road bike, ergo 19mph over the same ground.

I appreciate that this is a rough estimate and that tyres make a big difference (RRalfs) as does the weight of the bike (26lbs mtn bike).

Thanks

turnerjohn

I ride both and theres no hard and fast rule . MTBing has so many variables even average speed off road isn't accurate throughout the year even on the same trails. Roads more neutral but depends loads on traffic, gradient and road surface. Best to use a heart rate monitor or power meter (if you can) will give you some ideas.
I've also found mtb I ride at a higher intensity then road where I ride around zone 4 but for much much longer....off-roading (quickly) is certainly more of a work out !

amaferanga

If you're riding with slicks on the road on the mtb then I very much doubt you'll get an extra 5mph. More like 2 or 3mph I'd say.

styxd

Yes, it will feel alot faster, but in reality it wont be much (although 3mph is still quite a bit)

estampida

so you would need 2 single speed bikes (1 mtb & 1 road) with the same ratio (2:1) to find this out

you would need to measure the cadence, distance and time broken down into sections of the route, as speed does not tell it all in efficiency.

but as a road bike is more aero there will be a strong advantage on a road comparison, also tyre foot print and rolling resistance will need to be made equal in some way

even at the values you quote (say mtb 12 mph and road 19mph) that is around 75% faster or 75 % easier ( big difference)

can you cover 75% more distance on a road bike? - at a push 100mls a day on a mtb would be enough to too much, but 175 mls on a road bike sounds possible

Thats before any 29'ers are thrown in for evaluation.....

Fatamorgana

Sorry - you misunderstood my question. I understand fully that there are many variables, that is a given and need not be covered as such. I've always found my speed on the road on a 26er and a 29er to be the same, odd as that may seem - same tyres and weight too. I was / am looking not at fitting slicks onto a mtn bike but jumping onto a road bike from a mtn bike (ama I think had the wrong end of the stick for a while there I think).

Reading the replies above I will take it that the view is about 3mph, for a bike with a far smaller tyre print and front profile and geometry as to the 5mph that had been quoted elsewhere a while ago.

As such on a club ride on a Sunday this would likely put me in the slow group as a starting point I assume at 17mph? I was told 18 to 19mph average over 3hrs would be the slower end of the medium paced group.

That was the purpose of trying to asses the likely difference as I am now looking at buying a road bike with a view to joining a club to ride with on Sunday mornings and such like. As you said, the mtn bike gives me a far harder work out on any given ride, it's far more cerebal too but I am finding that the road riding is good for Base Training and some distance work which I'm enjoying more and more; plus up here in N Herts, there are a lot of roadies out on the Sundays so it'd be pleasant to join them with a suitable road bike instead of trying to keep up on a mtn bike - and mostly failing!

Thanks

finnjävel

I recently got my first road bike and I'm seeing an increase of about 5 km/h in cruising speed on the road. Of course there are too many variables and my sample size in rides is too small to say anything scientific, but that's what it looks like.

Fatamorgana

Yes, I'm seeing about 5kmph too.
Since I'm back-to-biking (8 weeks or so), albeit in a limited capacity, I'm managing 17.5mph 'round a British Cycling certified 10 mile TT course on a 30lb mtn bike with 2.1 tyres.
The next time I will try on the newly aquired Trek road bike and hopefully crack the 20mph / 30 minutes barrier.