Significantly less power on my roadbike than on my mountainbike

Hey guys,
I have big power and heartrate differences from my mountainbike to my roadbike.
Example: MTP = 210w with 130hr /// Roadbike = 210w with 145hr

I do not think it is necesarry the powermeter difference (both from Quarq). On the roadbike I get a sore feeling very fast during efforts. Not so on my mountainbike. There I can hold a higher amount of power for much longer duration.

Can you guys help me with my poweroutput on my roadbike?

Kind regards

Sore? Where?

Adjust your fit, firstly. Perhaps you have some subtle hip shift which would mean your power points across the pedal circle is not the same.

Some of it may be viewed at in the torque circle of your peddle stroke between the two bikes.

The other may be being too low. A good fitter will see all of this when they look at/analyze your hips. How low you can go depends on your flexibility, which also manifests in when/where your hips rotate.

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Do you ride your mtb more? I also feel like I able able to generate more on my mtb’s, but I would assume it’s postural (wide flat bars).

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Sore on the quadriceps femoris.
When I put the roadsaddle on the same height as on the mountainbike I get saddle sores.

Yes I was riding mountainbike more. Maybe the flat bars have an impact.

  • That is a dangerous assumption. At the least, you need to consider the reality that each power meter has a power data tolerance, and if the two are stacked in opposite directions from the “real” number, that could be a notable portion of the difference. Until you do testing to compare the two, you must keep that in mind as one variable in the discussion.

To your main question, it’s all but impossible to evaluate this without more details, to include pictures and/or video of you riding both bikes. Essentially, it’s best to consult with a bike fitter so they can evaluate your fit on each bike.


Do you use the same saddle on your road and MTB? I have the same saddle on both of mine, Pro Stealth. Also are your crank lengths the same? I swapped mine out so I have 170’s on both.

Can you share some more details about these measurements? For how long are you holding that power? Is it indoors or outdoors? Is it an average power over an interval or a ride, or is it normalised power?

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Is your example from attaching these two different bike to the same trainer?

Over what period is your example, 20mins? 1hr?

There will be a difference between different power meters, how different you can only find out from testing.

I would suspect wider stance (Q Factor) on the MTB vs. road bike.
Bill Black

Some folk are more comfortable putting out more power in a different riding position. I don’t mtb myself but I put out more power dancing (figurative speech) on the pedals of an upright road compared to an aero position on a TT bike. So some differences on different bikes is to be expected add that to the difference in power meter it can be substantial. Both pm may be accurate to +/- 2-3% but if one reads low and the other high the difference can be up to 6%

That’s taking into account static sag on the MTB, right?

What? Assuming a person measure saddle height in a typical way (Center of Bottom Bracket, along the Seat Tube Angle, to the Top of the Saddle), suspension sag is irrelevant.

  • Sag would only matter if someone measures seat height from the ground, which is a bad idea IMO.


I agree. Personally, I think this power problem has more to do with hip angle, pelvic rotation, and torque application across the pedal circle. That plays into the TT position vs a road position. MTB is even more upright.

But, definitely first thing to check is the saddle height.

Getting saddle sores when the road bike is at the same saddle to peddle as the MTB doesn’t make sense. There must be some movement of the hips.

Also MTB crank length is 175, 170, 165. Road is in 2:5mm increments, but it will affect the overall length.


I just want take a moment to show just a few of the potential fit related issues here. It is far more complicated than any single dimension given above.

  • Saddle Height (Taking into account differences in saddle, crank length, Q-factor, shoe/pedal combination, pedaling style differences between road & MTB, etc.)

  • Saddle Fore/Aft (Related to above, with likely differences related to body position for bike handling, that lead to power variation as well.

  • Handlebar Reach/Drop (Relative position from saddle to hands, with includes final Reach & Drop position, as well as width and hand orientation).

All of the above lead to a functional body position that can have a direct impact on the RPE and output from the rider, as well as comfort and injury issues (like the sores).

  • Also absent from the OP is sufficient detail about the comparison other than power & heart rate. Questions about the terrain use for each comparison are relevant. Differences in relative pitch and even surface condition can lead to notably different rolling resistance, inertia and relate demand on the rider.
  • Cadence is even a notable factor that must be matched if you are using heart rate for comparison. It’s variable on it’s own from all the influences we know, so matching conditions on the bikes as much as possible is the only way to have even moderate confidence in HR as a comparative data point.

Essentially, this is way more complex than can be summarized in a few sentences, and requires lots more info from the rider on the testing and bike setups.


Agree, before going into any fit related issues, its worth checking that there is an actual power discrepancy and not just a bad comparison between two rides.


Yeah, for sure.

I would definitely consult a fitter and get both bikes fitted (at the same time for a discount) so things are in the same general ballpark. The fitter should be able to discuss the differences too (and why there are differences), especially if they’ve got all the computerized tools with sensors/lasers.

But, that said, I do know (for a fact as it happened to me when I do crude adjustments when building a bike before a proper fit) that if my saddle is a tad high, my power drops as I cut short of a full peddle circle and reach the bottom with a tippy toe.


Yup, I pointed that out as well, specifically because the OP brushed it under the rug.

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That you did!

I’m vaguely recalling a mountain bike I had where I had an issue where the saddle felt way too low - I then realised when sitting on it I was compressing the suspension, effectively shortening the seat tube. Hopefully I’m not imagining that!

It was a bike similar to this, from a glance it looks like that would happen here?