Tried another bike, why was it quicker?
Discussion
I had a go on someone else's bike the other day, it had a power meter so naturally I wanted to beat the owner's high score. My sprinting efforts were significantly compromised by me not coping very well with the different handling but one thing that did come out of it was that, at higher power levels, it was somewhat faster than I achieve of my own bike.
Without going mad I was hitting just shy of 33mph on this bike, whereas I can put maximum effort in on my bike and not see 30mph. This is obviously quite annoying and I daresay will be quite expensive/enjoyable to resolve.
But why? Candidates:
1) Position/geo - my bike is set up for commuting and has a slightly less aero position, my bike has less racy geometry
2) Panniers - as above, I usually have an Ortlieb sticking out at the back
3) Placebo* - my effort assessment is wrong and am comparing a sprint halfway through a commute to one on fresh legs
4) Conditions - wind / gradient effects
5) Mechanical factor - tyre pressures, other drivetrain/bearing losses, rims rubbing on brakes
6) Measurement - GPS device vs wheel rotation sensor
6) Something else / all the above
Without going mad I was hitting just shy of 33mph on this bike, whereas I can put maximum effort in on my bike and not see 30mph. This is obviously quite annoying and I daresay will be quite expensive/enjoyable to resolve.
But why? Candidates:
1) Position/geo - my bike is set up for commuting and has a slightly less aero position, my bike has less racy geometry
2) Panniers - as above, I usually have an Ortlieb sticking out at the back
3) Placebo* - my effort assessment is wrong and am comparing a sprint halfway through a commute to one on fresh legs
4) Conditions - wind / gradient effects
5) Mechanical factor - tyre pressures, other drivetrain/bearing losses, rims rubbing on brakes
6) Measurement - GPS device vs wheel rotation sensor
6) Something else / all the above
- Note the difference in power between 30 - 33mph is ~25%.
Edited by TheInternet on Sunday 15th November 19:22
TheInternet said:
I had a go on someone else's bike the other day, it had a power meter so naturally I wanted to beat the owner's high score. My sprinting efforts were significantly compromised by me not coping very well with the different handling but one thing that did come out of it was that, at higher power levels, it was somewhat faster than I achieve of my own bike.
Without going mad I was hitting just shy of 33mph on this bike, whereas I can put maximum effort in on my bike and not see 30mph. This is obviously quite annoying and I daresay will be quite expensive/enjoyable to resolve.
But why? Candidates:
1) Position/geo - my bike is set up for commuting and has a slightly less aero position, my bike has less racy geometry
2) Panniers - as above, I usually have an Ortlieb sticking out at the back
3) Placebo* - my effort assessment is wrong and am comparing a sprint halfway through a commute to one on fresh legs
4) Conditions - wind / gradient effects
5) Mechanical factor - tyre pressures, other drivetrain/bearing losses, rims rubbing on brakes
6) Measurement - GPS device vs wheel rotation sensor
6) Something else / all the above
33mph? Without going mad I was hitting just shy of 33mph on this bike, whereas I can put maximum effort in on my bike and not see 30mph. This is obviously quite annoying and I daresay will be quite expensive/enjoyable to resolve.
But why? Candidates:
1) Position/geo - my bike is set up for commuting and has a slightly less aero position, my bike has less racy geometry
2) Panniers - as above, I usually have an Ortlieb sticking out at the back
3) Placebo* - my effort assessment is wrong and am comparing a sprint halfway through a commute to one on fresh legs
4) Conditions - wind / gradient effects
5) Mechanical factor - tyre pressures, other drivetrain/bearing losses, rims rubbing on brakes
6) Measurement - GPS device vs wheel rotation sensor
6) Something else / all the above
- Note the difference in power between 30 - 33mph is ~25%.
Edited by TheInternet on Sunday 15th November 19:22
In a sprint or just going for it on the flat?
What power were you producing?
My good bike and winter bike are setup near as dammit (
) identically, I find when I fit the guards for winter it's harder to maintain my summer speeds but otherwise there isn't a great deal of actual difference. However the good bike does feel nicer and provides a nicer sensation of the effort am putting into it.z4RRSchris said:
neither measure power? so how do you know that X watts on one is X watts on the other
One of them had a power meter, but that's irrelevant other than to verify the plausibility of GPS speed measurement. My own imaginary power meter tells me that even with greater effort I was significantly slower on my bike. I've tried to capture the possibility that I've got it wildly wrong in option 3, but would be surprised if I've misjudged ~30% extra power.Add:
7) frame flex
8) wheel flex
9) wheel bearings
Air resistance increases with the square of speed. At sprinting speeds your limiters are aerodynamics and your power output. If the latter was (fairly) consistent, it's likely down to aerodynamics primarily. See pictures of Cavendish head on in a sprint to see how small to the wind he is.
7) frame flex
8) wheel flex
9) wheel bearings
Air resistance increases with the square of speed. At sprinting speeds your limiters are aerodynamics and your power output. If the latter was (fairly) consistent, it's likely down to aerodynamics primarily. See pictures of Cavendish head on in a sprint to see how small to the wind he is.
Greg66 said:
At sprinting speeds your limiters are aerodynamics and your power output. If the latter was (fairly) consistent, it's likely down to aerodynamics primarily. See pictures of Cavendish head on in a sprint to see how small to the wind he is.
There seems to be a strong consensus about the aero thing. Since I spend very little of my commute over 25mph it should probably just be ignored, however I'll take a look at some of those alternative luggage options. That Cavendish though, he doesn't even have a rack on his bike, no wonder I don't go as fast as him...Aero is significant at much lower speeds than 25mph (did you mean 25kph?). Of all the factors you mentioned I'd suggest panniers will have the biggest impact. After that it's probably the difference in body position. Things like narrower bars can make a significant difference to your frontal profile, as well as the obvious candidates like a lower back.
Thought I'd do a comparison of the bikes (
), the Planet X is not as different as I expected but is definitely lower at the bars amongst other things.
These pics don't demonstrate the actual set up which puts the Planet-X further ahead before you even consider all the clutter strapped on to mine.
), the Planet X is not as different as I expected but is definitely lower at the bars amongst other things.These pics don't demonstrate the actual set up which puts the Planet-X further ahead before you even consider all the clutter strapped on to mine.
Edited by TheInternet on Monday 16th November 15:11
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