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3 years commuting average speed:
mountain bike with xc tryes = 0
mountain bike with slicks = +2mph
road rat with flat bar = +3mph
road rat with drop bar = +4mph
weight weenie road bike I don't need = ??
The variation across the spectrum of MTBs though is far greater than the difference between a fast MTB and a road bike.
No, I disagree, read my post just above yours.
Just dug out a post I made a year or so back on something vaguely similar.
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**Non-scientific anecdote alert**
There's a segment on my normal commute, which by virtue of being on my commute I've done 307 times as of this morning.
This has principally been done on two bikes:
22lb Allez with mud guards and that
17lb Madone without mudguards and that
At various times I've had a real dig on this segment (it's 0.7 miles, a shallow (2% average) climb, normally I just plod up it, depends on wind, whether I'm KoM or not etc etc. Just downloaded the average stats (and removed the times there were traffic lights on it) for the two bikes and the results are as follows:
Allez:
176 attempts
2:38:56 average
1:50 fastest
Madone:
69 attempts
2:37:32 average
1:48 fastest
So... on that segment it makes sod all difference - 1.2 seconds, or roughly 0.9% difference. That's over 2 years and various levels of fitness. Annoyingly you can't download power data from Veloviewer, as I've always got a PowerTap on the Allez, and often have it on the Madone too.
So, through the miracle of woeful extrapolation, and to answer the OP's question if the Madone was consistently 0.9% faster, and your 50 miles took 3 hours then I'd be 1.62 minutes faster. I think.
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Since I wrote that I have a new 'nice' road bike, which is faster, but it's still not in the realms that people are talking about on here of being 30%+ faster, and I've not done similar assessment on quite how much faster.
The variation across the spectrum of MTBs though is far greater than the difference between a fast MTB and a road bike.
Agreed - but Esher Shore specifically mentioned a lightweight XC 29er, and my comment was aimed at that.
Hmm.. but without knowing the bike, lightweight and XC mean different things to different people.
Esher Shore has posted pictures of a carbon Stumpjumper before, and said he raced XC at a national level. Fair to assume his definition tallies with mine at least, but our experiences of the speed differential varies significantly!
I think the speed differential varies quite significantly depending on the mtb you're talking about, however the OP sounds like he has a lightweight hardtail with a head down position and fast rolling slicks. It is by no means going to be 1/3rd slower (as some MTBs undoubtedly will be), but it will by all means be slower.
I think the difference between my fast road bike and commuter is about the same as the commuter to the XC bike (with 26er semi slicks on). The difference from this to my big bike is far bigger (on road/canal towpath type riding anyway).
OP will only know by buying a road bike and getting it set up nicely.
NJee - You've posted stats for 2 road bikes though not an MTB and a roadbike
Position woulm make the most difference (once you'd got the knobblies off) and I'd reckon your 2 bikes are pretty similar in set up? Esher shore doesnt say whether he's put slicks on his mtb either
Also esher shore might be running out of top end gearing wise on descents add al that upo and it might make a bit more difference than your exemple
NJee - You've posted stats for 2 road bikes though not an MTB and a roadbike
I know that, it was more in response to gti's comment about "fast road bikes" making a big difference.
Gearing is a bit of a non issue unless you're running a 28t single ring IMO. Red herring.
here are the 2 bikes in question:
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The road bike? I can easily ride at 35 km/h with little effort.
To roll that fast on the MTB I would be pushing hard, there is a lot of resistance from the tires and aerodynamic drag from the up right riding position.
The road bike is much faster to accelerate from a standing start - which is constant during my London commute with many traffic lights.
The MTB works well if the journey is uninterrupted as the heavier and larger (29") wheels hold speed well once rolling.
If I need to go fast (late for work) and the road is clear (i.e. Commercial road) I can go well over 50 km/h on the road bike, no chance of hitting that on the MTB.
Then consider the gearing (adjusted for 700x 25c road tire / 29 x 2.0" mtb tire)
Gearing on the road bike: 125.1" - 38.1"
Gearing on the MTB: 98.3" - 20.5"
Molgrips opined "You'll be in agony after 5 miles."
Certain sections of the road community would say if it's not hurting you aren't trying hard enough 🙂
(I am not one of their number).
Just had a look at my little shake down segment on Stava, I've done it on my Kaffenback (Heavy road sort of thing) and my Singular Swift 29er with 2.4" wide tires on. Kaffenback is 2X10 and the Swift at the time was 3X8....
The Kaffenback was 46 Seconds faster over the about 4 miles quick run around, on one of the climbs I was 15 sec faster on the Kaffenback a whole 0.8mph faster....
Kaffenback 14.7 mph average, 38.7 mph top.
Swift 13.1 mph average, 31.3 mph top.
Of course I'm very unfit and just like nice bikes.... as you can see the difference for me is bugger all but I would rather take the Kaffenback on my commute.
Cheers, Steve
It's not just about how much faster a road bike is than a mountain bike but the effort involved in maintaining that speed. I can certainly maintain a similar if not identical speed on my mountain bike but only for a few miles and I'm jiggered afterwards. Put in a hill or two and I'm nowhere near.
I certainly couldn't commute day after day on my mountain bike at the same speed as on my commuter (a Genesis Croix de Fer) which is about 10% slower than my Spesh Roubaix, more correctly [b]I'm[/b] 10% slower on the Genesis. I might, just might, manage it for one day.