Technical Q&A with Lennard Zinn – More tire talk

By Lennard Zinn

Dear Lennard,
Aargh — so much about getting UST tires on the rim (seelastweek’s Technical Q&A), now what about some help with getting themoff!?!?

I mounted my tires pretty easily, but I just bought some Stan’s andneed to yank them off again to install the Stan’s. And I can’t for thelife of me get them off. Any help?
Philip

Dear Philip,
The first thing you need to do is to deflate it completely.

Starting opposite the valve, push one bead inward with your thumb sothat it drops into the rim valley all of the way around. That reduces thecircumference it encompasses when you push it over the rim.

Adjacent the valve, push or pull that bead over the top of the rim.Do NOT start removing the bead opposite the valve. It should be obviousthat the valve prevents the beads butting up against it from dropping downinto the rim valley, so when you try to push the tire off on the oppositeside of the rim from the valve, you are forcing it over the maximum circumferenceyou can and making life as hard as you possibly can for yourself. Thisapplies to all tire removal—not just tubeless, and this is the trick thatallows you to remove road tires without tire levers and impress your friends.

Once that bead is off, now push the other bead into the valley all ofthe way around and, starting next to the valve, push or pull it over therim as well.

Now, if you are using a rim like the Bontrager for UST I mentioned lastweek with the plastic sealing rim strip, the valley is not as deep or wideas on a Mavic UST rim, so it will be harder to do. This makes it imperativethat you only push one bead into the valley at a time, since there is notroom for both in there, as there often is with a Mavic UST rim. (And theextra rubber bead flap on a UST tire makes the bead fatter, so space inthe valley is at a premium anyway.) Similarly, if you are using a tirewith a really tight bead like those IRC Seracs I mentioned last week, youcan have yet more trouble, and if you have both, it will be tougher. However,the above combination is the ONLY combination with which I have ever hadto use a tire lever for installation or removal of a UST tire.

Unless you have very weak thumbs, you should be able to remove almostany UST tire without tire levers by using this technique. And if not, itcertainly should not be a lot of trouble to get them off with tire levers.

As always, squirting some water around the rim will also help lubricatethe bead so it slides over more easily.
Lennard

A note on UST tubeless vs. tubeless with standard tires
When I was visiting Lion Tyres in Thailand (perhaps you saw thestory I wrote about it in the currentissue of VeloNews),a Geax design engineer told me that standard tires depend upon the tubefor some of its resiliency and performance, and that using one withouta tube gives you insufficient sidewall support. Then, I received this letterfrom another tire designer in response to my last week’s column:

Dear Lennard,
I have tested tires for over 15 years for a number of tire companiesgoing back to the Farmer John days. There is a very big misconception aboutthe conversion of standard tires to tubeless via a “Stan’s” approach andusing a real tubeless tire. In testing of all the major brands usingboth methods, I have realized that a real tubeless tire outperformsa standard tire converted hands down! Here is why.

First, we are talking about high end racing cross country tires. Thisis the category most affected by this technology. A standard (Race) tireis designed with the lightest, thinnest most supple casing to ensure agood ride quality and light weight. These casings rely on a (nicely babypowdered) inner tube to support the side walls and help transfer energyto the dirt. When you convert a standard tire, you remove a major componentin the transfer of the riders energy into the ground.

The sidewalls of the tire will in effect “twist” ( like the side wallsof a top fuel dragster’s rear tires ) and a LOT of energy is lost. Thisalso accelerates the breakdown of the casing material and will make themmore susceptible to failure. In the beginning, most tubeless tires useda slightly stronger casing while others used only internal coating. Thethicker casing did transfer energy very well though. Now that this technologyhas developed over the course of a few years, the weight has come downas well.

The new lighter UST tires ride extremely well and transfer energy perfectly.I have seen some of the new 500ish gram models and they are light and dohold air. Unfortunately at the expense of some of the ride quality. Sofar only one company seems to be able to maintain performance and reduceweight dramatically…and it’s not from France.

Second, some of the brands out there do use a slightly differentbead profile. This is to ensure a good bead lock on a tubeless designed(UST) rim. Converting a wheel to tubeless will not ensure that you getthe necessary beadwell profile. In ALL of my tests, the use of a real tubelesstire has outperformed (in ride quality, traction, longevity, and powertransfer) the lighter standard versions of the same tire. Every time! Andthe use of a UST wheel set also made mounting and maintenance allot easier. Don’t get me wrong. I have probably paid off Stan’s car with the amountof Goop I have purchased of the years. I do use the sealant in my tiresas a precaution. I regularly ride with a lot of guys who swear by conversions.They also do the maintenance necessary to maintain peak performance wheremost don’t. I have also found that the Innovations sealant is probablythe best I’ve ever used. The coagulant works much better (Stan’s doesn’tactually have a coagulant material added ) and it stays wet forever. Noneed to “refresh” it. But it might not work to seal a conversion as wellas Stan’s.

In all my years research, I feel most as a lot of people do, riderspay a far too much attention to the scale and I have seen it result ina “placebo” effect. They are so happy that the bike weighs 87 grams lessthat they fail to see what the real affect is. Also when converting anybrand tire or wheel to tubeless, you’re using products outside of theirintended design parameters. This pretty much means when it comes to warranteeissues, there is a good chance that all bets are off. So remember to cleanall of the goop off and get rid of the “latex smell” before yousend them back saying “I was just riding along and all of sudden………….”!
Mark Salmon
International Sales Associate
Product Development
Intense Tire Systems
www.Intensetires.com

Numbers, numbers everywhere
Dear Lennard,
I am about to buy new tires for my newest bike. For the first timeI tried to read all of the information that is on the tire and rims. Thetires are Michelin AXIAL PMO and say on the sidewall 3-622(700-32c).The rims are Rolf Vector Comp ETRTO 622X12, Front 270mm, Right 258mm, Left290mm. What in the world is the meaning of all of these numbers which Ipresume the manufacturer wanted me to read?

I was planning on purchasing 700X20 tires as I have for all of my otherbikes. But I feel that may be a mistake. Should I go for 700X23 tires instead?What are my compromises? I will probably buy Michelin Pro Light tires.
Robert

Dear Robert,
ETRTO is the international tire and rim standard, and 622 refers tothe actual rim specification diameter for 700C. The “Front 270mm, Right258mm, Left 290mm” are the lengths of the spokes on your Rolf wheels, specifically on the front and on the drive and non-drive side of the rear (the Rolf high-low hub flange explains the large length difference between driveand non-drive side spokes (the drive side is always a bit shorter, dueto wheel dish, but this difference is due to the disparity in hub flangediameters). You can put 700X20 tires just fine on these wheels. None ofthese numbers mean anything to dissuade you from that. But why do the 20mmanyway? The only reason can be weight (like for a climbing race withoutany descending), because cornering and rolling resistance are both worsewith the skinny tire, except on a perfectly smooth track. And of course,durability is also reduced.
Lennard

That one little spot…
Dear Lennard,
I ride a Cervelo P3 as my race bike, so I am keen to have as littledistance between the curved seat tube and the tubular tire on my back wheelas possible. However, I don’t seem to be able to get the tubular to adhereto the rim as well at the site of the valve as I can on the rest of therim. Any suggestions?
Angus

Dear Angus,
I have experienced what you are talking about, where the tire doesnot seat down on the rim next to the valve. But it is so long in the pastthat I don’t remember if it was on cheap training tubulars or on nice racingones (although I would bet it was with the former). Now, the only tubularsI have are nice racing ones, and I just looked, and none of them that aremounted on rims have any adhesion problems near the valves. They are sittingdown nicely and tightly there.

Also, a method that I describe in Zinnand the Art of Road Bike Maintenance and in my new Zinn’sCycling Primer coming out in June that might help is to surround thetire with a Pony clamp when gluing it. A Pony clamp (also called a miterclamp) is a nylon strap with a little winch on it to pull the loop of nylontightly around something (like a picture frame, usually). Strap one ofthese around your tire and cinch it down. It is always a good idea to getbetter tire adhesion to the rim this way, and it might also stick downthose parts right by the valve that you mention.
And check the below response as well.
Lennard

Answer from tubular expert and USA agent for Vittoria, Tom Petrie:
Dear Lennard,
If I understand the question correctly, it sounds as though Angus hasa high point on his tire above the valve. I’d speculate that the problemis more likely with his tire than with his gluing technique (I hope he’susing a brand other than Vittoria!). If there’s a bulge where the casingbutts up against the valve, no amount of gluing will reduce the high point.

I also wonder how much of a high point we’re talking about. If the rearwheel is so close to the seat tube that a 1mm variance in wheel circumferencecauses the tire to rub, then I’d suggest he’s too close, even if the wheelis perfectly round. The possibility of picking up road debris that mightjam or (for a guy who is this fanatical) air flow restriction issues probablyoffset whatever advantages he’s gaining by bringing the tire so close tothe seat stay.

Vittoria has a zero tolerance for circumference variance at the valve.
Tom Petrie
Velimpex Marketing, Inc.

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Technical writer Lennard Zinn is a frame builder (www.zinncycles.com), a former U.S. national team rider and author of several books on bikes and bike maintenance including the pair of successful maintenance guides “ Zinn & the Art of Mountain Bike Maintenance” and “Zinn & the Art of Road Bike Maintenance.”Zinn’s regular column is devoted to addressing readers’ technical questions about bikes, their care and feeding and how we as riders can use them as comfortably and efficiently as possible. Readers can send brief technical questions directly to Zinn. Zinn’s column appears here each Tuesday.