Frame Flex on GCN

[dddd]

kramnnin wrote:
"...I'm just curious what causes the dead feeling. Though...a frame that feels dead to me may feel lively to someone else... "


I would first look very carefully at the weight and performance level of the wheels, tires and even tubes, then the frame, particularly the front and rear center dimensions and the frame's weight.

Lastly the rider's fit, down to details like handlebar width and stem length, anything that might make the bike feel more laborious to put power into (while seated and while standing).

I regularly refurbish older bikes and notice that an old-school chain seems to absorb a lot of power in response to any given degree of cross-chaining, also that some components like bottom brackets or derailer pulleys can have a lot of bearing/seal drag from old grease.

[cachagua]

The model [in the GCN video and the bikethink-dot-com article] is that you squeeze the frame between two forces, applied at the pedal and at the rear wheel. In response the frame flexes, and when you reduce one of the forces squeezing it, the frame unflexes, and the strain energy it had stored does some work.

Where does it do some work? It does some work where the force was reduced.

And that's exactly what happens when you're actually riding, only when you're riding, it's switched around the other way. When you're riding, the resistance at the rear wheel stays the same, like the pedal pressure did in the video -- and when you're riding, the force from your pedal is what's reduced, whenever you come around to the part of your pedal stroke where your force drops below its maximum.

This make sense to anybody?

[kramnnim]

Originally Posted by cachagua

This make sense to anybody?

To me it does, yes.

[Black Dog]

Originally Posted by kramnnim

Certainly...I'm just curious what causes the dead feeling. Though...a frame that feels dead to me may feel lively to someone else...

I might suggest that the dead feeling is more about perception than the frame itself in the case of you getting back on a frame after a long time. You may have become used to the feeling of the other bikes and by contrast the old bike feels very different.

[cachagua]

Changed my mind.