SuperPershing

lets get to the point

Its true that high flange means much stiffer. But is it truly "More power transfer"?

Scrodzilla

A stiffer rear wheel will naturally result in better power transfer, so long as your crank arms and frame don't flex like wet noodles. Just how stiff and strong a wheel is also largely depends on the rim, number and type of spokes used and whether or not the wheel is built well.

zubes5280

Sure, the wheel will be stiffer - but does that actually mean "more power transfer"? If components flex, is there really any loss of power?

TejanoTrackie 

When components flex, energy is wasted that would otherwise be used to propell the bicycle. So, yes, there is a loss of power. However, the power that is lost in elastic flexibility of a hub flange, is totally insignificant when compared to other losses, such as spoke windup and tire deformation. The reason that high flange hubs result in stiffer wheels is that they shorten the length of the spokes and provide a larger pulling component tangent to the flange. So, it is not the stiffness of the flange that matters, but rather the resulting wheel geometry.

SquidPuppet

Question.

Taller flanges means shorter spokes at a greater angle. Most people seem to agree that combination makes a stiffer wheel.

Is it possible that the increased leverage resulting from the increased spoke angle, and the fact that the spoke holes are farther from the axle (more leverage), could cause the flanges themselves to flex more than a low flange hub's would?

I'm going to test this.

Be right back......


OK, I'm back. The high flange hubs felt mushy and their fatigue life was reduced. A LOT. Plus they are heavy and ugly.

I'm staying with low flange.

seau grateau

There's also the principle of "more stiff doesn't matter when stiff enough will do."

TejanoTrackie 

Also known as the point of diminishing returns.

Bandera

On a properly built & tensioned wheel w/ any flavor of hub flange there is effectively Zero difference in "power transfer".

Hardware does not produce "More power", the rider does.
Lacking "More power"?
Ride your bike "more".
Want even "More power"?
Ride your bike "more"in the hills.

-Bandera

tyrion

TMonk

doubt it makes a real world difference. just pedal harder

JohnDThompson 

Yet at a time when most bikes came with large flange hubs, Eddy Merckx set his hour record on this bike:

TejanoTrackie 

Eddy Merckx could have set the hour record on a Schwinn Varsity.

seau grateau

BRB drilling holes in my bike.

SquidPuppet

JohnDThompson 

Well, sure, but that's only because the Varsity has large flange hubs!

Ghrumpy

"Much stiffer" what? "More power transfer" where?

The only thing a Chubhub really does differently is transfer power across the hub barrel, so both flanges are involved in transmitting drive torque to the rim. A traditional small-barrel hub transfers very little torque from the drive side to the non-drive side. Of course such a large barrel requires large flanges, unless you want to make the spoke hole circle smaller than the barrel diameter. (It's been done....)

Does it make any difference? @TejanoTrackie is on the right track (pun intended.) Spoke crossing pattern makes a lot of difference. Spoke thickness makes a lot of difference. Rim stiffness makes a lot of difference.
Flanges make little if any measurable difference in wheel stiffness, and probably no difference you can feel.

Elastic flex of some materials induces fatigue and failure. But whether elastic flex of a bike and its components is "wasted" energy is not necessarily true. While it may seem axiomatic, humans are not machines, and clearly a certain amount of "flex" can allow for the human body to perform better. Think of mountain bike suspension. Anyone remember when that was considered "inefficient?"
If that flex makes it difficult to control the bicycle, then it's not a good thing. But that's an entirely different issue.

zubes5280

I guess I just don't understand where the power goes if it's not propelling the bike forward. If I press down on a spring with the same force as I press down on a solid block of metal, I'm exerting the same amount of "power" on both surfaces, the spring just absorbs the power and stores it as kinetic energy until I let go, when the spring would spring back. If spokes(or crank arms, or anything for that matter) flex, won't they "spring back" with "lost" power?

TejanoTrackie 

Force =/= Power

kinetic energy =/= potential energy

apple =/= banana

dabac

There's a thing called hysteresis(sp?)
Basically, it's about springs not being perfect accumulators of energy. Some of the energy you put in and take out is lost to internal "friction" in the material and becomes heat.


Now, for steel the amount is really, really tiny. But still there. I wouldn't worry about it.


What I'd consider more important is human/bike interaction.
Us humans are quite sucky as measuring devices WRT absolute values.
But we can be surprisingly sensitive WRT relative change.
It might well be that we're able to pick up on the change in RESPONSE rather than total energy expended, and for that reason prefer, and feel faster on stiffer wheels.
And a rider who feels faster may well try harder.


This is one of the rather apparent things on shaft-drive bicycles, the wind-up if you stomp on the pedal.
(sure, there's those two lossy bevel gears too)
It can be noticed on belt-drive bikes as well.

dabac

Let's not forget "only because something is true doesn't guarantee that it's important".

checoles

I used to have a full blown track bike that I would stupidly use on the roads (young crazy hipster) and the stiffness in the frame/components was unbelievable. It would bounce and skip like mad, and any imperfection in the road would send the bike bouncing out of it, due to the pure stiffness of the thing. It's like swinging a baseball bat at a tree, the bats gonna come right towards you on the rebound. With these more road suited fixies, they're more comfortable and have some flex in them. However, they're no where near as quick as the track bike, even with a few pounds of difference in weight. I think thats down to the stiffness and power transfer.

seau grateau

I'm not sure if I just got dunked on or not...

ThermionicScott 

Pretty sure he was agreeing.

motrheadsroadie

chubhubs are so ugly.

SquidPuppet