Cyclocross Racing - Tire Pressure Experience with Maxxis Raze.

I am currently using Maxxis Raze in races, and trying to narrow down an effective tire pressure, but I'm finding that traction appears to be just as effective at 60psi than below the rated minimum of 50psi.

What has been your experience?

60psi !?! Wow...granted i'm pretty light but i run my razes 35-40 psi...

wayne

Indeed Wayne, I felt that it was rather high as well. I've tried well below 50, and have not noticed more traction, but slower due to the greater resistance. I'm light as well (150lb), could this be a reason?

I've tried well below 50, and have not noticed more traction, but slower due to the greater resistance.This is backwards. Within reason, lower pressure gives lower rolling resistance off-road.
http://www.bicicletta.co.za/Downloadable%20docs/Rolling%20Resistance%20Eng%20illustrated.pdf
A 150# guy running 60psi on 34c tires, you must bounce around like crazy on uneven grass or dirt.
["Meadow" and "gravel" are mislabeled on page 7.]

Awesome article flargle, thanks. Bouncing has honestly not been an issue, but it may be course dependant. I guess this now leads to the question of what is an appropriate low pressure for these tires "within reason"......

Start with 40. The tradeoff is between feel and pinch-flatting.

Wayne, have had much pinch flatting between 35-40?

Hey Flargle,

I hadn't seen this article, but this is the exact type of thing that I was asking about when you showed me where to buy 26" cyclocross style tires. I was digging on all sorts of websites, and Schwalbe's site talks about the wider tires rolling better.

Now I'm _really_ confused.

Hey Flargle,

I hadn't seen this article, but this is the exact type of thing that I was asking about when you showed me where to buy 26" cyclocross style tires. I was digging on all sorts of websites, and Schwalbe's site talks about the wider tires rolling better.

Now I'm _really_ confused.I agree it's confusing. With tire width, the tradeoff is with weight. Weight does matter because (1) the amount of accelerating you do on a cross course and (2) portaging.

The Schwalbe article doesn't have enough data to fully distinguish the effect of tire width from tire pressure. They show the effects one at a time, I'd like to see the full 2-dimensional relationship.

Another confusing aspect is that UCI cross rules forbid tires fatter than 35mm. While this doesn't apply to local series, the trickle-down effect rules everything, so the fast guys are running 32-34mm. Would a high-quality 45mm tubular run faster? We'll never know because nobody's making it. Pros run tire widths toward the top end of the UCI limit, but it's a chicken/egg conundrum.

Imagine if the UCI loosened up their cross rules. Then a pro could test a range of tires on a private course, run some hot laps with a power meter and heart rate monitor, and in a season or two you'd see if the riders (and the market) moved toward fatter tires.

Wayne, have had much pinch flatting between 35-40?

None whatsoever...I've run them as low as 32 psi without any problems but figured I was pushing my luck :) I'm heavier this year at ~136lbs but haven't had any problems and depending on the course I don't think you'd have any problems running in the 35-40 psi range...

wayne

Flargle brings up a good point. Speaking of width I ran 700 x 40 speedmaxes in a rather bumpy race and liked them quite a bit, aside from the weight (they're tanks). A wide, fast rolling (low center nobs) tire definately has it's place IMO.

I agree 60 is too high, even for trail riding where pinch flatting is a bigger concern. I run less than 40 in most tires on most courses and also weigh about 150.

Dugast Rhino 700x43c tubulars. Only $140 per tire. Perfect for your next monstercross build.
http://us.st12.yimg.com/us.st.yimg.com/I/cyclocrossworld_2021_6888663
I'm pretty sure they'd fit under my cross frame and fork. That'd be very fast and fun on the local singletrack.

Dang, I wonder how many of those they sell.