Blog Posts From Active Expert: Gale Bernhardt Tagged With tire_pressure

Equipment changes for the 2012 Leadville 100 Mountain Bike Race

guest — Thu, 02 Aug 2012 22:56:23 GMT

Over the last six months or so, I’ve made several changes to my S-Works Epic 29er. Here’s the list and why the change:

Changed from a SRAM 38x24 to a SRAM 36x22. Though I muscled my way through racing last year on the 38x24, I decided to make the change to lower gears when I was pre-riding the Breckenridge 68 course. I just wanted lower gears so I could do more spinning and less power riding. For me, though the 38x24 is fine for rides on the Front Range, this change is critical for the long climbs at altitude at Breckenridge and at Leadville.
Cut one inch off of the ends of both handlebars. Last season I noticed that I was close to clipping some trees on narrow singletrack races. On an early season race this year, I clipped an rock that was hanging over the trail in a narrow section. (You’d think I would have taken the hint then…) On the Breckenridge pre-ride I noticed my handlebars were wider than one of my riding buddies, Scott Ellis. He is 5’9” tall with very wide shoulders. Why am I riding such wide handlebars? Since the change, I’ve noticed my handling skills have improved. Geeze, the issue of the coach having improper bike fit, like the plumber that has leaking pipes in his/her own house.
Put on new bar grips. My hands will fall asleep on long rides with technical descents. I’ve tried other ergonomic grips and didn’t like them. I put on the BG Contour XCT Grips and love them. They are smaller and more comfortable (the surface gives more) than other grips I’ve tried. If I’m comfortable, I ride faster.
More tire pressure. Ugh. This was a result of belching a tire on rock drop and not noticing. With the tire soft, it caught on the rim on a benign section of trail. That turned my handlebars 90 degrees in less than a flash and I went over the bars. I can run softer tires on non-technical courses, but if there are drop-offs I use more pressure.
Varied fork and shock pressure. It does take awhile to figure this out, but I use different pressures for different courses. I use more pressure in the fork for courses that are very technical and have drop-offs.

How does this help you?

Though you’ve been riding your mountain bike for awhile, maybe years, is it set up optimally for your current level of fitness and for the specific races or rides that you do?

If it’s been awhile since you’ve checked some of these items, I think it’s worth a look.

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Questions and discussion can be found on my Facebook page.

Cycling and mountain bike training plans can be found here.

Answer to, “What mountain bike tire pressure is best to avoid slit tires and punctures?”

guest — Sat, 28 Apr 2012 23:01:51 GMT

Last blog I wrote to technical guru Lennard Zinn to ask the best tire pressure to avoid slit tires. Boiled down, my question was:

Q: If I ride a course that is littered with shale and I want to avoid getting a slit in my tire, does tire pressure make a difference one way or the other? Using a balloon and pin theory – if I poke a fully inflated balloon with a pin, it pops almost immediately. If I poke a half inflated balloon with the pin, the balloon gives quite a bit before failure. One argument is that I should keep running my low tire pressure. Another theory is that more air in the tire may have deflected the shale not allowing it to sink into and slice my sidewall.

So, when running tires on a shale and rocky course do I run more air than normal, less air or run “normal” pressure. (“Normal” being what I would run for a rocky course, sans patches of shale.)

Also, is there any scientific evidence anywhere (that I couldn’t find)?

Here is Lennard’s reply:

A: Wow. Good question! Unfortunately, I don't know the answer. My guess would be that the lower pressure would probably reduce punctures more over the long term, but I have no scientific data to back that up; it is only a hunch.

Thanks for your question for my column.

Keep the wheels turning,

Lennard Zinn

President, Zinn Cycles Inc.

Senior Technical Writer for VeloNews

Author of bike maintenance books and other books

7437 S. Boulder Rd.

Boulder, CO 80303-4641 USA

ph. 303-499-4349

email veloqna@comcast.net

www.zinncycles.com

What mountain bike tire pressure is best to avoid slit tires and punctures?

guest — Fri, 27 Apr 2012 15:40:46 GMT

Often, mountain bike racers are concerned with the optimal tire pressure to run to decrease rolling resistance or to improve traction on particular courses. But, what is the optimal pressure to avoid slits and punctures?

My recent experience at a race got me wondering about tire puncture theory. I couldn’t find anything online, so I sent the following note to technical guru Lennard Zinn:

Hey Lennard ~

Hope this note findsyou doing great.

I’m having a debate with myself – and others – about mountain bike tire pressure. Not regarding speed and power output – but puncture resistance. Over the weekend I did a race at Pueblo Reservoir, the Voodoo Fire. Rolling through a benign section of trail (non-technical, relatively flat, no big obstacles) I kicked up a piece of shale and it sliced the sidewall of my tire – near the tread.

Though I think it was simply bad luck the way I hit the piece of shale – does tire pressure make adifference one way or the other? Using a balloon and pin theory – if I poke a fully inflated balloon with a pin, it pops almost immediately. If I poke a half-inflated balloon with the pin, the balloon gives quite a bit before failure.One argument is that I should keep running my low tire pressure. Another theory is that more air in the tire may have deflected the shale not allowing it to sink into and slice my sidewall.

Also, is there any scientific evidence anywhere on this subject (that I couldn’t find)?

In advance, thanks for the answer/theory.

Gale

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I’ll let you know what Lennard has to say. In the meantime, what do you think? Higher pressure or lower pressure? Let me know your opinion on my Facebook page.