#1
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Handling changes at low temperatures?
I went out today at 19F for a 20 miler and I think I noticed a difference in how the bike handled in turns. The tires are 650Bx38 Gravelking slicks run at about 40-42 psi tubeless (at least, in the basement). I wonder if they cool down enough to have the pressure drop and that affects the handling. Nothing major, it just felt a bit different.
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#2
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It would make sense as cold makes rubber harder so less grip.
Same with car tires and why they develop winter tires with a different compount that does not harden up as quick as summer or all seasons. |
#3
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Agree, same for rock-climbing shoes, for especially thin/technical routes we'd time our climbs based on temps.
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#4
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I bet you lost a few pounds - well, the tires did. When my 40mm tires are softer for trails (<40), they handle noticably different than when pumped up to 50+.
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#5
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might be the man and not the machine, methinks.
my old bones take a while to warm up in teen weather. |
#6
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P2 = (P1*T2)/T1 for a constant volume right?
So if your basement is 65F (mine is...) than T2 @ 19F is 36.5psi (if i did my back of envelope math right...) - so yes, that's a pretty big change IMO
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http://less-than-epic.blogspot.com/ |
#7
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I noticed the same thing when I started riding Hetres years ago. Three big temp swings; from inside to outside to night: 70°->55°->32° dropped the pressure enough to cause self-steer during cornering and also had the tires grabbing the raised paint lines.
Rode for years with 700cx25 in same and colder weather and never noticed a difference. Lower pneumatic/ground trail I suppose, funny that. |
#8
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Yes, in theory, if the air in the tires is at the basement temp to begin and equilibrates to the air temp, that's about 3-1/2 psi aroud 40-41 psi to begin with. but I don't know how much the temp of the air in the tires drops in a ride that takes 85 minutes (extra slow so I don't sweat.) And I don't know how the colder temp affects the tire (vs. how it affects the grip on the road). I imagine that with tubeless, the air cools faster.
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#9
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Quote:
for 42mm tires there is definitely a pressure where they feel too low and sloppy, it's noticeable and i dont like it. just pump them up a little higher next time initially when you know it's that cold out. i bet you'll notice a difference.
__________________
http://less-than-epic.blogspot.com/ |
#10
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If using the gas laws, the temperature has to be in Kelvin. And when you do the conversion, the pressure ought to drop to about 40 psi at 19 F from 42 psi at 65 F.
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#11
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i did the math. kelvin and pascals yes.
__________________
http://less-than-epic.blogspot.com/ |
#12
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It is the percentage reduction whether Rankine or Kelvin, about 9%, which is 3.6 psi starting at about 40 psi.
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#13
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A 9% change in pressure will obviously affect handling. But I'll bet the durometer of the rubber changed more than that, which is going to affect hysteresis, compliance, grip, and rolling resistance. As noted above, there is a reason that they make winter tires - and it's just for snow and ice grip. At low temperatures many winter tires outperform summer tires even on dry pavement.
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#14
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Just wondering if grease in the headset (especially), bottom bracket, wheel axles, etc. might affect handling in cold weather. Most Shimano users are aware of slower shifting in cable actuated “brifters” in the cold.
Sent from my iPhone using Tapatalk |
#15
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Quote:
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