Tire Pressure for IMCDA...
Not sure what tire pressure I should run.
Zipp 808s Clinchers with disc cover
Conti GP4000s with Butyl tubes
Rider weighs 160#
What would be ideal for front/back tire pressure?
0
Not sure what tire pressure I should run.
Zipp 808s Clinchers with disc cover
Conti GP4000s with Butyl tubes
Rider weighs 160#
What would be ideal for front/back tire pressure?
Comments
If it were me (meaning I lost ~30lbs and actually weighed 160lbs) I'd be running ~110psi in both front and back. (but I'd also be running Latex Tubes with butyl spares)
I know you're running Conti's, but here's a chart from Vittoria which is consistent with other things I have read. http://www.vittoria.com/tech/recom-tyre-pressure/ Basically says you could go 105 front and 110 rear. Also, when you add in the weight of your bike, you could go as high as 115psi in the back.
BUT, I'd still personally go no higher than 110/110.
for my weight of 155 + bike, Zipp recommends 126 psi fr/rr BUT this is for their tubulars (which are Vittoria's rebranded).
for clinchers, max pressure is probably under this. plus factor in road surface, rain, etc in lowering pressure a bit. not sure if this helps...
Rain? WTF?
Yeah, I know what you're saying on the latex. That ship has sailed. I dumped my Vittorias and Latex setup in favor of more puncture-resistant GP4000s (knock on wood).
Are Conti GP4000s running latex vs. butyl really that big of a difference?
Oh yeah... I forgot you sold your Vittoria tires and Latex tubes to some random dude on ST (instead of to me
)
Quality tires and latex tubes are the shit. I know I can feel the difference.
I'm training on Vittorias I bought for IMWI last year, with butyl tubes. The Vittorias are awesome.
Back to the original question: I think I ran 110psi in the front and 115psi in the back in Madison.
Where's that PDF that says so?
Here it is...I think this is the most current. http://www.biketechreview.com/tires_old/images/AFM_tire_testing_rev9.pdf
Not seeing 5 watts though...
this is CDA and it ain't Friday yet...
See R's comments...
Yes, having done this one before I'm aware that your forecast in CDA is whatever the weather is when you walk out your door on race morning. A buddy of mine was a weatherman in the PacNW for several years and he said any forcast longer than 48 hours is a crap shoot at best. And he said even getting it right inside of 24 hours is difficult.
Closet is packed. Hitting the road @ 8am tomorrow. See you there!
The chart is watts per wheel. You can certainly see where latex tubes improve a fast tire by 2-3 watts per wheel over a butyl tube.
They did not test GP4000s with butyl tubes in that link. However most other tires that were tested with latex and butyl, the difference was ~2.5-3.5W per tire x2 wheels on your bike = ~5-7W.
So I'll re-ask the question, how important is 5W to you? How important is piece of mind with your original tire/tube dicision? There is no wrong answer, you just have to know which is more important to you. Most tires will not puncture on race day. But any tire "can" fail on race day. It's really about where you want to push the odds of an event happening... 1%, 2%, 5%...? How important in potential margin of is 5W?
I'd say, run what you have. GP4000s and Butyl with 110psi/110psi. That will give you the best piece of mind on race day which is very valuable.
But if you're on the bubble for KQ, then screw the extra 3% chance of fail and take the 5W and hope for the best.
How many flats have you gotten per mile of training? For me, personally, it's very, very small and I ride all manner of roads and terrain. IMO, selecting race tires with flat prevention taking precedence over decreased rolling resistance is the wrong way to go, given that I ride hundreds and hundreds, and thousands of miles without getting flats.
New tires, inspected for nicks and cuts.
Air them up to recommended PSI
Keep an eye out for rocks, glass, pavement seems, potholes, learn how to bunny hop stuff to avoid pinch flats.
IOW, do the same stuff in a race you do in training and you'll be fine with regards to flats.
Couple of flats in the last 6 months. Both within a couple hundred yards of each other on the same stretch of road - which is cursed BTW.
Besides reliability there's another reason I switched out the Vittoria Open Corsas for Continental GP4000s' - those Vittorias are a total bitch to get on/off an 808. I have every tire lever and jack known to man in my box and they stretch out very, very little. If I had to change out a tube in the field it would be more than interesting. We're talking 15-20 minutes to muscle that thing back on. Continentals are a tight fit but not too bad.
Perhaps a Conti + Latex is a good comprimise?
Got it. One wheel vs. two...that makes sense. Thanks.
Exactly. I give no thought to flat prevention on race day. 90% of clincher flats are pinch flats and that's usually user error. Be sure there's no tube between the tire and rim and you'll be good to go 99% of the time.
Training is different. I worry about flat prevention much more in training and run Gatorskins. Don't care much about rolling resistance in training. Those tires are heavy and roll like shit but they're durable.