rear wheel spin

"steveb" <[email hidden]> wrote in message
news:gIwZh.88354$_c5.22832@attbi_s22...

Quoted message said:

Is there any relationship between how long a freewheel will spin while in
a stand and the quality of the hub? Can it relate to amy significant drag
effects on the road?

My Campy Protons will spin seemingly forever in the stand while my
Reynolds wheel will stop after 5-10 revs.

Seems you'd have variable drag in the hubs depending on:
- quality of the bearings
- adjustment of the bearings
- viscosity of the grease in the bearings
- friction due to freewheel/cassette ratchet mechanisms
- friction due to hub seals
- probably more I can't think of right now.

And, is the initial acceleration applied to the wheels standardized somehow?

If how many revs a wheel will coast in a stand before stopping is a direct
indication of hub quality, the pricey Chris King hubs I put on my MB are
absolute POS compared to the cheap Shimano ones I put on my daughters MB.

Cal

me said:

"steveb" <[email hidden]> wrote in message
news:gIwZh.88354$_c5.22832@attbi_s22...

Quoted message said:

Is there any relationship between how long a freewheel will spin while in
a stand and the quality of the hub? Can it relate to amy significant drag
effects on the road?

My Campy Protons will spin seemingly forever in the stand while my
Reynolds wheel will stop after 5-10 revs.

Seems you'd have variable drag in the hubs depending on:
- quality of the bearings
- adjustment of the bearings
- viscosity of the grease in the bearings
- friction due to freewheel/cassette ratchet mechanisms
- friction due to hub seals
- probably more I can't think of right now.

And, is the initial acceleration applied to the wheels standardized somehow?

If how many revs a wheel will coast in a stand before stopping is a direct
indication of hub quality, the pricey Chris King hubs I put on my MB are
absolute POS compared to the cheap Shimano ones I put on my daughters MB.

Cal

One issue you didn't mention is the rotational momentum, or inertia, of
the wheel. A heavier wheel, especially if the rim and tire are heavier,
will have a lot more inertia and will therefore take longer to stop due
to bearing friction.

Another issue is that many bearings have rather different amounts of
drag depending on how the bearing is loaded. In the case of a chain,
for example, its efficiency is lower when the chain is under less
tension.

In short, comparing hubs by spinning is nearly meaningless if the hub is
built into a wheel.

--
Ted Bennett

steveb said:

Is there any relationship between how long a freewheel will spin while in a
stand and the quality of the hub?

I use front and rear spin times as a means of assessing bearing
adjustment, as there's no other accurate way of judging cone tightness
once the play has been removed. My Sturmey front hub will spin for 8
minutes and the rear gear hub manages 4 minutes when it is optimally
set up. I tighten the bearings and then loosen in systematic steps
until i get the right spintimes. It's a good was of checking to see if
the bearing have tightened up over several hundred miles.

I should think a good Campy freehub should manage a heck of a long
time and produce little drag when looking at road performance. It
would be interesting to see if there's a spin time difference between
ceramic, cup/cone and normal high quality cartridge bearings. I've
just tried a Maillard Atom and that manages 11 minutes. Tried a bottom
bracket spin but it's hopelessly unbalanced so comes to a halt in a
few seconds.
Cheers, Nick.

Quoted message said:

steveb said:

Is there any relationship between how long a freewheel will spin while in a
stand and the quality of the hub?

Quoted message said:

I use front and rear spin times as a means of assessing bearing
adjustment, as there's no other accurate way of judging cone tightness
once the play has been removed. My Sturmey front hub will spin for 8
minutes and the rear gear hub manages 4 minutes when it is optimally
set up. I tighten the bearings and then loosen in systematic steps
until i get the right spintimes. It's a good was of checking to see if
the bearing have tightened up over several hundred miles.

I should think a good Campy freehub should manage a heck of a long
time and produce little drag when looking at road performance. It
would be interesting to see if there's a spin time difference between
ceramic, cup/cone and normal high quality cartridge bearings. I've
just tried a Maillard Atom and that manages 11 minutes. Tried a bottom
bracket spin but it's hopelessly unbalanced so comes to a halt in a
few seconds.
Cheers, Nick.

I suspect that if the bearing is anywhere near adequately
adjusted/lubed/clean, you are probably measuring the mass of the
rim/tire more than bearing efficiency per se.

I do not know that as a fact and welcome any data or a different insight.

--
Andrew Muzi
www.yellowjersey.org
Open every day since 1 April, 1971

A Muzi said:

Quoted message said:

steveb said:

Is there any relationship between how long a freewheel will spin while in a
stand and the quality of the hub?

Quoted message said:

I use front and rear spin times as a means of assessing bearing
adjustment, as there's no other accurate way of judging cone tightness
once the play has been removed. My Sturmey front hub will spin for 8
minutes and the rear gear hub manages 4 minutes when it is optimally
set up. I tighten the bearings and then loosen in systematic steps
until i get the right spintimes. It's a good was of checking to see if
the bearing have tightened up over several hundred miles.

Quoted message said:

I should think a good Campy freehub should manage a heck of a long
time and produce little drag when looking at road performance. It
would be interesting to see if there's a spin time difference between
ceramic, cup/cone and normal high quality cartridge bearings. I've
just tried a Maillard Atom and that manages 11 minutes. Tried a bottom
bracket spin but it's hopelessly unbalanced so comes to a halt in a
few seconds.
Cheers, Nick.

I suspect that if the bearing is anywhere near adequately
adjusted/lubed/clean, you are probably measuring the mass of the
rim/tire more than bearing efficiency per se.

I do not know that as a fact and welcome any data or a different insight.

--
Andrew Muziwww.yellowjersey.org
Open every day since 1 April, 1971- Hide quoted text -

Dear Andrew,

My tests seem to support your suspicions.

A long time ago, I measured spin-down times from 30 to 10 mph on the
same wheel and tire with a stop watch and speedometer, comparing a
normal tube, the same normal tube with 80 grams of weight added, and a
Slime tube that was 80 grams heavier.

The addition of 80 grams of plain weight or slithery slime increased
the spin-down time noticeably.

Oodles of details and even graphs here:

http://groups.google.com/group/rec.bicycles.tech/browse_thread/thread/c9ba3e288c0f28d4/cb76085614097330?lnk=gst&q=carl+slime+spin&rnum=1#cb76085614097330

Here's a quick link to a crude graph:

http://home.comcast.net/~carlfogel/download/slime.jpg

The 80-gram lighter normal tube (red line) spun down from 30 mph to 10
mph noticeably faster than the Slime tube (blue line) or the normal
tube with 80 grams added (green line). The data points show 20 tests
for each kind of tube.

The Slime tube (blue line) slowed down a tiny bit faster than a dry
tube with weight added (green line).

A soggy mess consisting of a few ounces of green Slime full of chopped
fibers should provide much more drag than any reasonably adjusted
bearing.

But the Slime-drag made only the tiny difference between the blue and
green lines.

This suggests that even the drag of the Slime slithering around in the
tube is negligible.

The chief drag in spin-down tests seems to be the wind drag of the
spokes versus the rotating mass.

Flip a bike upside down, crank the rear wheel up to speed, and you can
feel the wind blowing even from the awkward fan of a couple of 2 mm
spokes.

The spin-down times would be considerably longer if I'd waited for the
wheel to stop instead of thumbing the stop-watch when it dropped to 30
mph and then again when it dropped to 10 mph. The force involved in
the wheel turning the last few spins is so small that a flick of the
finger will stop it.

Cheers,

Carl Fogel