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Does less temperature equal less rebound?

Started by Razzo Bolognese, October 20, 2009, 02:56:48 PM

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Razzo Bolognese

October 20, 2009, 02:56:48 PM
This is the first time I've ridden in 40 degree weather and it seems to me that my bike has a bit less rebound.  Granted I haven't checked the tire pressure but if oil slows down when cold, wouldn't it make sense that the oil in my forks couldn't do their job as well as when they're warm?  Please factor in a great depth of ignorance as you respond.  Thanks!

-Dan
2005 M1000S repainted to the proper Ducati Dark, CRG levers, open clutch cover, KN& Air filter, genuine knockoff Napoleon bar-end mirrors, Michelin Pilot Powers, PIAA Super-White headlight bulb, 9000 miles and counting.

ducpainter

#1
October 20, 2009, 03:09:38 PM
The effects of low temps should go away quickly as the oil will reach temp just by the movement of the forks.

A tremendous amount of heat is created by forcing the oil through the valve orifices.
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Paegelow

#2
October 22, 2009, 08:44:38 AM
If anything, colder oil would increase damping because the oil viscosity would be a little higher

Razzo Bolognese

#3
October 22, 2009, 08:59:07 AM
Quote from: Paegelow on October 22, 2009, 08:44:38 AM
If anything, colder oil would increase damping because the oil viscosity would be a little higher

Again, please forgive my ignorance but why the F would oil have MORE viscosity when it moves SLOWER?

-Dan
2005 M1000S repainted to the proper Ducati Dark, CRG levers, open clutch cover, KN& Air filter, genuine knockoff Napoleon bar-end mirrors, Michelin Pilot Powers, PIAA Super-White headlight bulb, 9000 miles and counting.

Scissors

#4
October 22, 2009, 09:16:37 AM
Quote from: Razzo Bolognese on October 22, 2009, 08:59:07 AM
Again, please forgive my ignorance but why the F would oil have MORE viscosity when it moves SLOWER?

-Dan

Correct.  Colder temperatures mean higher viscosity, which means higher compression and rebound damping.

Howie

#5
October 22, 2009, 09:21:36 AM
The cold oil is thicker, so it has more resistance when going through the valving.  Think of oil as a slushy and the straw as a hole in the high speed valve in your shock.  When the slushy is nice and cold drinking it through the straw is difficult.  Warm it up, it becomes thin and goes though the straw easily.  When your bike is parked outside in the cold the oil gets thick.  Ride around a little while and the movement of the forks warms the oil and it becomes thinner.

Hope this helps.

Razzo Bolognese

#6
October 23, 2009, 09:11:45 AM
Aha!  The little 2 watt bulb is shining BRIGHT today!  I'd assumed (incorrectly) that viscosity was a measure of slipperyness and I was thinking that warm oil is more slippery than cold oil.  Thanks to the interwebs I now know that viscosity is a measure of THICKNESS.  Of course cold oil would be more viscous than warm oil!

http://en.wikipedia.org/wiki/Viscosity

Thanks guys for schooling my iggorant a$$!

-Dan
2005 M1000S repainted to the proper Ducati Dark, CRG levers, open clutch cover, KN& Air filter, genuine knockoff Napoleon bar-end mirrors, Michelin Pilot Powers, PIAA Super-White headlight bulb, 9000 miles and counting.
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