July 27, 2021

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Specialized FAQ: high-speed shimmy, tubular tires, accuracy in tire pressure

6 min read

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Have a question for Lennard? Please electronic mail him at [email protected] to be bundled in Specialized FAQ.

Pricey Lennard,
1 other concern I’ve been indicating to request is about your latest thinking on the dreaded shimmy. Recognizing now that it’s a bifurcation and not an oscillation, I’m pondering how a lot is devices, and how much is rider enter? I believe I pointed out that the shimmy occurred a several months in the past to a pal on a contemporary road bicycle (a newish Trek Domane). He is a a lot less seasoned rider and was in a horrible crosswind. Are there approaches he can use to keep away from a repeat efficiency? I have been advising him to place all his weight on the pedals, floating off the seat, with unfastened palms on the bars, but mostly since which is what I do, and I’ve in no way professional any shimmy in 50+ many years.
— Steve

Pricey Steve,
The occurrence of a shimmy needs a link concerning the wheels, just like a cell phone made of two tin cans linked with a taut string. If you can wholly de-body weight just one wheel, the oscillation will go away, just like you can not area a get in touch with on the tin can cellular phone if the string is slack.

Peter Sagan could probably split the link between the wheels in practically any situation by pulling a wheelie heck, he could in all probability also do a nose wheelie at any time. Possibly would remove shimmy, but few men and women can do that.

Pushing the butt off of the back again of the saddle to get the fat as far again as possible and possessing no pounds on the entrance wheel ought to halt it. It usually takes a big leap of religion to pull that off at high speed on a violently shaking bike, however.

Just clamping your knees in opposition to the best tube damps a good deal of the oscillation and does not involve these types of a leap of faith.
― Lennard

Expensive Lennard,
I appear to be to recall that you are rather of an authority on tubular tires. Do tubulars of a given width appear up rounder/broader on a rim (of offered width) than their clincher equal?

I not too long ago listened to a podcast showcasing an job interview with a senior rep from Challenge tires, who spoke about their emerging tech including tubeless tubulars, and some new tubular tape (I at the moment use Carogna, but definitely some levels of competition would be no bad issue). Do you have any perception on this?
— Steven

Expensive Steven,
In solution to your to start with issue, the respond to is most definitively certainly a tubular tire is absolutely spherical in cross-area, while a clincher is bulb-formed.

The Challenge tubeless tubular was discovered by accident, when the latex tube experienced not treated completely prior to staying place inside of of the casing, and it caught to the casing. Now, Challenge does that deliberately and permanently adheres the tube to the interior partitions of the casing. My guess is that it can make for a really quick-rolling tire that is protected towards punctures by sealant and in opposition to pinch flats not only by the deficiency of a tube, as tubeless clinchers are, but also by a flatter rim that doesn’t increase up the sidewalls with a thin major edge to either pinch the tire or to be bent or cracked by a really hard, sharp-edged effects. I intend to check this hypothesis soon.

Zinn 40th anniversary headbadge. Image: Lennard Zinn

As for Challenge’s new tubular-gluing tape, I a short while ago received some. It appears to be just like 3M VHB tape, most likely 5952 3M tape, but perhaps 5962 3M tape (thicker, denoted by much larger final two digits). I haven’t experimented with it for gluing tires. We use 3M 5952 to glue on your 40th Anniversary of Zinn Cycles head badges, and it is fantastic for that it’s extremely really hard to clear away the head badge if you put it in the mistaken position or upside down. I really don’t know if it can outdo Carogna for keeping tubulars onto rims.
― Lennard

Expensive Lennard,
In reply to a query from Kimball about a bigger valve typical for tubeless, you point out in your reply that you “can’t envision the bike field likely by means of the large upheaval it would get to switch to a different standard”.

When I assume of the countless proliferation of bottom bracket specifications, disc brakes, broader rims and tires, and all the rest, I can envision the market earning these kinds of a move. If there is income to be made. Presently, in the bicycle marketplace, early obsolescence of beautifully usable products appears to be the new regular. As an instance, striving to get hold of pieces for “legacy” (ie, 3-4 yrs. outdated) Zipp wheels or Powertap energy meters is a chancy proposition. The Powertap has been discontinued as are some not-incredibly-aged Zipp products, so very good luck with that. As you know, the two are now in the SRAM steady, alongside with Time pedals, much too. As a Time person because 1990, I’m setting up to gather cleats, mainly because with SRAM, who is aware how extended I’ll be ready to journey these two-yr-aged pedals in the long term?
— Pierre

Expensive Pierre,
Stage taken. I’ll preserve an eye out for new tire valves.
― Lennard

Expensive Lennard,
I was constantly wondering why my ground pump gauge commences at Bar.

As we all know, we never live in a vacuum. I’m generally at sea stage so it should examine 1 Bar to get started with. So, I guess it is some sort of conference amongst various makers, that gauges at pumps start off at .

What I was in truth asking yourself is, if my tire suggests max force 8 Bar and my pump commences at zero, how substantially strain do I actually have inside of my tire by the time I access 8 Bar? If the commence on the gauge is zero, and I know for a simple fact I am at 1 Bar atmospheric tension, by the time gauge reads 1 Bar, I am by now at 2 inside the tire. So, by the time I achieve 8 Bar on the gauge, the tire is truly at 9 Bar exceeding the max force authorized. Or, I’m lacking a little something?

It’s possible you can make clear in handful of words what is this all about?
— Sead

Pricey Sead,
The pump reads zero whenever the strain inside of the hose equals the pressure outdoors of the hose. So that indicates it reads zero when it is not pumping, whether you are down at 282 feet down below sea level in Death Valley (ambient stress = 1.03 bar), or when you are at the prime of Mt. Everest (ambient force = .337 bar).

When the pump reveals 1 bar, it usually means that the pressure it is reading through in the tire is 1 bar (14.5psi) increased than the ambient strain, observe that its complete force is 1 bar.
― Lennard


Lennard Zinn, our longtime technical writer, joined VeloNews in 1987. He is also a tailor made frame builder (www.zinncycles.com) and purveyor of non-personalized enormous bikes (bikeclydesdale.com), a previous U.S. nationwide team rider, co-author of The Haywire Coronary heart,” and writer of a lot of bicycle textbooks which include Zinn and the Artwork of Highway Bicycle Maintenance,”DVD, as perfectly as Zinn and the Artwork of Triathlon Bikesand Zinn’s Cycling Primer: Servicing Guidelines and Ability Building for Cyclists.” He retains a bachelor’s in physics from Colorado Faculty.

Follow @lennardzinn on Twitter.

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