Gear

Technical FAQ with Lennard Zinn: Tires at season’s end and more glue talk

Lennard and readers discuss the care and handling of tubulars at the end of the season and the intricacies of proper gluing methods.

Andy Schleck got a wheel change during the cobbled stage of the Tour de France
What's this all about? See below.

Q.Dear Lennard,
I saw in your column last year that you removed your ’cross tubulars at the end of the season (and then rinsed out the sealant). Is it necessary to remove the tires at the end of the season?
Alison

A.Dear Alison,
I have always recommended removing tubulars annually, and a lot of that I think came from racing in the 1970s and 1980s with Clément red glue, which tended to get very dry, hard, brittle, and powdery over time. The tire could come off easily once the glue became really dry. But the Vittoria Mastik One glue I’ve been using since carbon tubulars came into vogue doesn’t seem to dry out as badly. Certainly, the tires I had on for a single ’cross season were hard to get off; the glue was not overly dry and was not powdery.

I asked Stu Thorne, manager of the Cannondale-Cyclocrossworld.com team, what he recommends for length of time to leave a tire glued to a rim, and here is what he said:

“Two years is the max. I feel that when I have peeled off tires that have a good glue job, I am amazed at the condition of the glue. I think that if the glue is at all dry then it would be a good indication that they should not be used.

“I guess when I say two years, I really mean two ‘cross seasons, which is more like 15-16 months. So not really much more than a year in the grand scheme of things. For example we glued many of the wheels (35 pairs) in September of 2009. So the wheels were used all of the 2009-2010 season. In March of 2010 at the end of the ‘cross season, we inspect all of our wheels — tires, bearings, rims etc. Anything with the slightest hint of damage or wear is replaced. In the case of the new tire rule, we stripped all the 34’s. If a UCI-compliant 32mm tire was in good shape we left it alone. If it had a worn tread or other visible damage it was replaced.

“The tires in good shape and left glued on the rims are being used today and are fine. I just tore off a tire that was damaged/flatted after Fort Collins. It was a last year’s tire glued in Sept of 2009. It was an absolute bear to remove. I can’t see peeling these off each season. Kinda the ‘don’t fix it if it isn’t broken’ sort of idea. I think that if I had to keep the tires and wheels another season, I would re-glue them.

So the shorter answer is, yes we leave them on, but I wouldn’t go year-after-year without a new glue job.”

Another reason to peel them off is that a lot of riders use the wheels they race cyclocross on during the road season. So it’s natural to switch them at the change of each season.
Lennard

Q.Dear Lennard,
I was wondering if you could elaborate on the “Belgian” method of combining glue with tape for ‘cross tubulars.

It seems to me that we are building something of a chain: rim-to-glue-to-tape-to-glue-to-tire … then that chain is only as strong as it’s weakest link. You’ve got a failure if any individual link fails.

From the instructions, the tape gets coated with glue and doesn’t directly touch the tire. How does adding it to the mix help?

If it works for the pros, I’m willing to try it based on that alone. But the nerd in me wants to know why it works!
Justin

A.Dear Justin,
The “Belgian Tape” from CyclocrossWorld.com, which seems to be identical to Jantex tape and I have used interchangeably with it, is very thin, tacky, and finely woven — finer than what you would find in duct tape, for example.

I think it holds the glue together and prevents it from snapping off a carbon rim the way the tests Chip Howat did at the University of Kansas showed. The mesh embedded in the glue holds the sections of glue together and perhaps forms overall a stronger bond. After peeling a tire, the tape is still part of the glue. In some sections it’s stuck to the rim and some sections on the tire, but in both cases it peels, rather than snaps off, and it doesn’t leave the clean sections of rim the way glue only sometimes can. Other gluing tapes I’ve tried tend to stay on the tire completely.

I also think the tape perhaps fills the center of a small-radius rim bed a bit so that the gluing contact area with the base tape of a bigger tire is enlarged. In other words, a 700 X 34 or 32mm tire doesn’t mate well with a rim designed with a 21mm-radius rim bed, meant for 700 X 19-23mm road tires. I have seen rolled tires in ’cross that clearly were only adhered along their outer edges. A method Simon Burney recommends in his book, and attributes to Dugast owner Richard Nieuwhuis, to better match the shape of the gluing surface to that of the tire, is to peel the base tape off an old tubular and split it down the center with scissors. After coating the rim with a thin layer of glue and letting it dry, smear glue down one side of your half-width strip of old base tape, and stick it down the center of the rim channel. Smear glue on top of the strip as well and continue with your gluing procedure. I think the gluing tape, with glue above and below it, might help increase the bonding area in a similar way.

I also think that the slight increase in rim diameter due to the tape helps hold the tire on better.
Lennard

Re:Dear Lennard,
Nice article on gluing cyclocross tubulars! I had a few comments and a question on it. One thing that can be done to prevent tearing from the rigid glue on the base tape is to put a very light layer on the tire before the final coat and mount on the rim; this will soften up the base tape coat so it won’t be rigid. When mounting the tire, I’d suggest first only pumping it up to 20-30psi as it will be easier to reposition on the rim to get straight; much higher and I’ve had issues getting the tire to move.

To really get the tire seated, I like to drop the air pressure to almost flat once I get it straight and roll the tire along a broom handle using my body weight to press the tire into the rim; this gets it set into the rim fully and will squeeze out most bubbles in the glue if you have them. For final air pressure to hold over night, I’ve popped a few going up to 100psi or more, so I rarely go over 85psi and usually only 60psi. Maybe I’ve just had bad luck though.

There is also a lot of debate about going higher than 40-50psi as it may cause the center of the tires to pull away from the rim if you are using a deeper radius rim, though I haven’t seen any tests showing either way. I prefer doing a glue-only method myself, though I’d be interested in a test between glue only (usually three layers on rim, with one or two on the tire) vs. the Belgium tape method.
Ben

Re:Dear Readers,
Regarding the ticking sound Zipp wheels can make at times, I came across some interesting images on my hard drive. Take a look. Even Andy Schleck’s mechanics put electrical tape onto his valve stems to keep them from clicking inside his Zipp wheels.

Lennard



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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 numerous books on bikes and bike maintenance including the pair of successful maintenance guides “Zinn and the Art of Mountain Bike Maintenance” – now available also on DVD, 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.”

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.