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Technical FAQ with Lennard Zinn: Blowing up tires, taking them off, and more

  • By Lennard Zinn
  • Published Oct. 19, 2010
  • Updated Oct. 21, 2010 at 4:28 PM EDT

Regarding the questions about different gases escaping differently from tires, it occurred to me to tell you about Prestacycle’s new product, just introduced at Interbike. Prestacycle is the company famous for the Prestaflator, a must-have tool for bike shops, which makes inflating tires to proper pressure with an air compressor quicker, easier, and more accurate. Its new product, Prestaflator 2go, is a small nitrogen tank that can inflate 40 tires. With hose and regulator, it sells for $130.

Prestacycle founder and president David Finlayson shows off the belt hook on the nitrogen Prestaflate tank.

You may well wonder why you’d want to inflate a tire with $3 worth of nitrogen instead of with free air. David Finlayson, Prestacycle founder and president, claims that a tire holds nitrogen pressure six times longer than it does with air. He explains that it is the oxygen that escapes fastest, so eliminating it keeps tires tight longer.

The Prestaflator 2go hose and regulator actually works with both nitrogen tanks and CO2 tanks. But, as we’ve discussed, CO2 leaks out faster than air. (Editor’s note: See David Finlayson’s clarification in the comments section below this article) With such a little tank (20oz.), 3000 – 4000 psi is required to inflate so many tires, namely 40 road tires from empty to 120 psi with a single tank. The tank can be hung from a user’s belt, so it is particularly applicable for running around and inflating tires quickly at a race or other bike event.

Also, a welder’s nitrogen tank can be installed in a bike shop and attached to a (standard) Prestaflator. Prestacycle recently acquired the Web address “bikenitrogen.com.” The site has yet to be built, but Finlayson plans to document on it the installation of a welder’s tank, which welding suppliers could deliver to bike shops. Tank swap-out costs around $30 and should inflate thousands of tires. The potential benefits include:

  • 1. No air compressor noise (when the compressor runs).
  • 2. No electricity needed.
  • 3. No moisture going into tires. Nitrogen inflation is dry and should be better for rubber, rims and tire valves.
  • 4. Potential to hold pressure longer.
  • 5. Potential to reduce heat in tires, resulting in lower rolling resistance.
  • Finlayson claims that items 4 and 5 are widely claimed in automotive and motorcycle circles.

To those who think that nitrogen tire inflation is a bit over the top, Finlayson says, “Remember that a 100-mile bike race is often won by only inches. Even the smallest difference in tire pressure loss reduction or rolling resistance can make the difference at the line.”

Getting tires off

Prestacycle’s other new tool introduced at Interbike is a tire lever with some unique features. The patent pending Prestalever tire tool, available January 1, has a second hook on the backside near the tip, as well as an insert in the handle end for holding steel driver bits. The Prestalever hooks over the rim as well as under the tire bead, so the user can just slide it around the rim and remove the tire very quickly. The lever plus a tiny set of tool bits replaces an entire multi tool with a set of levers (except for the chain tool), thus saving weight and space.

The PrestaLever, now just in prototype form, will be able to hold tool bits in the handle.

I’ve been using a prototype Prestalever (without the bit-holding insert), for a couple of weeks now and find it amazing. It does what the Quik-Stik () and original Crank Brothers tire levers promise to do for removing tires, but I find it to be easier and faster to use than either, thanks to the notch on the back of the head. (Arguably, the Quik-Stik offers a second feature, namely mounting tires quickly).

I find that with the Prestalever, I can just dig the lever under the bead, hook the backside notch over the rim, and slide it around. I pride myself at being able to remove tires with only my hands faster than most people can do it with levers, but now I no longer have any desire to do so! The only time the process slows down is if the inner tube is very strongly adhered to the inner tire; then I really have to push down hard on the tire as I begin moving the lever to free the bead enough to come out over the rim.

Though bigger and less appealing for carry-along purposes, Prestacycle will soon offer a “Pro” tool-bit set as well. This presumably is to use with its mini ratchet wrenches, but these bits (like all mini bits) would also work with power drivers and mini torque wrenches. Made from hardened S2 steel, the Pro bits have long shanks and will provide extended life. The long bits promise to be a big benefit for getting under brake hoods to remove road levers.

Holding tires on

The new Hed 5 carbon tubular wheel is intended for rough cobblestone racing like in Paris-Roubaix and the Tour of Flanders, as well as for cyclocross. The rim is wide — as wide as a tubular’s base tape, in fact — and is aerodynamically as well as glue-dynamically (no, there’s no such word) optimized for a 25mm-width tire. And the fiber layup is designed to maximize bump absorption, not stiffness. “This is not a sprinter’s wheel,” remarked Steve Hed at Interbike.

The top of the rim of the Hed 5 Paris-Roubaix/cyclocross wheel is as wide as the base tape of a tubular tire.

Hed pioneered (followed by Zipp and others) the concept of a rim/tire combination whose widest point is behind the tire, so it forms a more idealized wing section whose leading edge is narrower than a point further back along the wing. The rim is as wide as 27mm behind the brake track.

The glue channel has a larger (12.5mm) radius of curvature, so the wider tire mates perfectly with it. The extra rim width and the lower-curvature glue channel together make the glue bond to fatter tires second to none.

The new OCTTO wheel from Mondo Design in Canada similarly has a low-radius glue channel optimized for a 25mm tire. Its rim width is not wide like Hed’s, but I just glued a pair of 32mm cyclocross tubulars onto a set of them. I’ll let you know how they work as ’cross season progresses.

FILED UNDER: Bikes and Tech / Cyclocross / Technical FAQ TAGS: / / / / / / /

Lennard Zinn

Lennard Zinn

Our longtime technical writer joined VeloNews in 1987. He is also a framebuilder, a former U.S. National Team rider, and author of many bicycle books, including Zinn and the Art of Mountain Bike Maintenance and Zinn and the Art of Road Bike Maintenance, as well as Zinn and the Art of Triathlon Bikes and Zinn's Cycling Primer: Maintenance Tips and Skill Building for Cyclists. He holds a Bachelor’s degree in physics from Colorado College. Readers can send brief technical questions to Ask LZ.

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