3 ms·

I think where the difference between flexible materials like carbon fiber and steel, and stiffer materials like aluminum is most easily observed is on rough roa

I think where the difference between flexible materials like carbon fiber and steel, and stiffer materials like aluminum is most easily observed is on rough road surfaces (like rumble surfaces or even cobbled stone).

jacquesm 6y ago
That and in the position of the bottom bracket, in a 'stiff' bike you'll definitely see much less movement of the bottom bracket (and thus less change in orientation of the pedals), on an aluminum based frame this can be quite noticeable while cycling, especially when standing on the pedals.
- discreteevent 6y ago
  There is an open question into whether the flex in the bottom bracket is recovered microseconds later into forward motion. Not much of the energy that goes into flexing a stiff spring is lost as heat. And could it even be beneficial because it works more naturally with the body of the rider? Sean Kelly rode some of the early "noodly" aluminium frames and if anyone could flex a frame, he could. Didn't seem to slow him down.
  - jacquesm 6y ago
    Oh, to clarify: I did not mean that it would lose you any energy, it is just something that is different.
- mariusor 6y ago
  Personally I've never felt the change in bottom bracket flexing, but I always feel how different frames feel on certain bits of road. Maybe I'm just not outputting enough power, I don't know.
  - jacquesm 6y ago
    Or quite possibly you have pretty stiff bikes. I have an oldie aluminum one that is so flexible that I don't like to drive it, an oldie steel one that is as rigid as they come and my 'regular' bike (and older carbon frame) is now living elsewhere so I can't compare them side-by-side anymore but it was pretty stiff as well. Tube diameter for the tubes connecting to the bottom bracket can make a big difference too. The tandem we have (a Koga 26") is pretty flexible too but it is kind of logical for being aluminum and that long, you can really tell if you're both pushing hard, the whole thing warps. But better bending than breaking!

jacquesm 6y ago

That and in the position of the bottom bracket, in a 'stiff' bike you'll definitely see much less movement of the bottom bracket (and thus less change in orientation of the pedals), on an aluminum based frame this can be quite noticeable while cycling, especially when standing on the pedals.

discreteevent 6y ago
There is an open question into whether the flex in the bottom bracket is recovered microseconds later into forward motion. Not much of the energy that goes into flexing a stiff spring is lost as heat. And could it even be beneficial because it works more naturally with the body of the rider? Sean Kelly rode some of the early "noodly" aluminium frames and if anyone could flex a frame, he could. Didn't seem to slow him down.
- jacquesm 6y ago
  Oh, to clarify: I did not mean that it would lose you any energy, it is just something that is different.
mariusor 6y ago
Personally I've never felt the change in bottom bracket flexing, but I always feel how different frames feel on certain bits of road. Maybe I'm just not outputting enough power, I don't know.
- jacquesm 6y ago
  Or quite possibly you have pretty stiff bikes. I have an oldie aluminum one that is so flexible that I don't like to drive it, an oldie steel one that is as rigid as they come and my 'regular' bike (and older carbon frame) is now living elsewhere so I can't compare them side-by-side anymore but it was pretty stiff as well. Tube diameter for the tubes connecting to the bottom bracket can make a big difference too. The tandem we have (a Koga 26") is pretty flexible too but it is kind of logical for being aluminum and that long, you can really tell if you're both pushing hard, the whole thing warps. But better bending than breaking!