Paging 11.4 re: tubulars

[LegendRider]

A friend sent me a copy the following letter to Zinn at VeloNews. The writer makes a lot of bold claims. Are they true???

Dear Lennard,
I read your article on Tufo tape in this week’s tech tips. Just a few comments.

You wrote: “The reason is that test results that I have seen indicate that the rolling resistance is higher with the Tufo tape than with rim cement. This is presumably due to energy loss through hysteresis, caused by the tape squirming around.”

I know this white paper and its conclusions, but it makes no sense. The study was also very poorly done with too many variables between the cement and tape wheels. It’s too bad it gets continuously quoted. This is a common problem with bike lab tests; most are very poorly done, with no replicates and indication of statistical significance. (My favorite is wind tunnel tests of wheels that use different tires on each wheel).

Tubulars don’t squirm on all tape (there are many brands, I’ve used three different kinds, and they are different), but they definitely do squirm on cement. Anyone who has tried to reposition or remove a tubular by each method can tell you this. In fact, most taped tubulars are extremely difficult to remove if the tires are new, and can even lead to carbon peeling on CF rims if not careful. Tape is glue, it’s just glue held in a cloth matrix. If anything, tapes bond too strongly in some cases.

I’m an admitted convert from glue, but tapes are a far more reliable method of attaching a tubular than cement; this is especially true in humid days in summer. As for rolling resistance, many I know who have tried each method cannot detect any measurable difference or feel in the tires. Unless I see some real data, this falls into the myth category with some theories and a lot of hand-waving.

So why do pro teams still use glue? This was the topic of conversation in Milan last year at the Giro with some mechanics. All have tried tape and say that a tire will never roll off from tape, and one said their riders felt they had less rolling resistance (!), but the problem is that pro teams have to strip off the tubulars after every stage and replace them. This would be impossible to do with 24-plus wheels in one night if they taped. Glued tires come off in one good yank. It’s actually disconcerting to watch.

I use tapes (I use Continental or Jantex) because I can mount a tire safely in 30 seconds and be on the road, and I can replace a tubular on the road if punctured with the same level of safety without limping home on an unglued or poorly glued tubular. I think someone has made a better mousetrap. This is argued by traditionalists, but if one is really concerned about rolling resistance, they should be riding clinchers or tubeless.

There are two issues here. One is that Tufo tape is different from other brands of tape, but conclusions about Tufo get applied to all other brands, based on one poorly done study. This really isn’t fair, as there are even big differences between glues.

Second is that self-published Internet data done by students without peer review needs to be taken with a big grain of salt.

In the KTL lab report, for example, they conclude that Tufo tape is inferior to glue in roll-off. However, they test roll-off by pushing the tire on the sidewall, which is a poor model (they should at least push the rim); they test the tape and glue exactly once; and they don’t follow the tape instructions as supplied by Tufo.

Maybe VeloNews should test different rim tapes at some point. The same tires, the same wheels.

The easiest test is to just get a few different riders to ride the same tires mounted on the same wheels by different tapes and glues. See if anyone can guess which is which beyond just chance.
Ray

[PeterNorth]

Is it true that pro teams replace every tire after one day of use???
I use mine for at least a week before replacing....
:rolleyes:

[Too Tall]

Wow, we've been down this road before. Yep, agree TUFO tape holds tyres like a bear however I do NOT see it ever doing as good a job as cement holding the tyres rim edge to edge OR the convenience to quickly change a spare. NO tyres don't snap off...if they do some lunk head did a terrible job gluing OR they are glued "gently" for other reasons (I use minimal glue for commuting).

I've removed many teammates tyres who used TUFO tape and it holds well. If you like tape use it...just don't ask me to put it back on ;)

TFHTF

[dirtdigger88]

I use tape on my tubulars

I figure that if I had Too Tall around to glue all of my tires - sure I would glue em- but I dont

I have to rely on my own skills of gluing (since I am sure Ive glued more tubulars than most of the guys at my LBS)

I feel that I get a more consistant job with tape compared to MY glue jobs-

tires dont squirm or roll- they are acutally harder to remove that glued tires ATMO

Ive been using tape for two seasons now- Im sold on it

but what do I know - I dont carry a spare tubular on most rides either- just a can of Pit Stop and some CO2 and my cell phone- I like to live on the edge

Jason

[LegendRider]

I wasn't aware that Continental made a tape.

Also, I don't want to rehash the tape v. glue debate. However, I'm curious if the idea that tape adds a bunch of rolling resistance might be a myth.

[stevep]

I wasn't aware that Continental made a tape.

Also, I don't want to rehash the tape v. glue debate. However, I'm curious if the idea that tape adds a bunch of rolling resistance might be a myth.

the whole thing is steeped in myth.
its like king arthur and the round table.

ride what you like and what works for you.
never think too much about this.
overthinking is the bane of the internet.

dont ask too tall about this subject.
he's biased...possibly crazy.
i heard he was being sent to a crazy camp in north carolina until he gets sane again.

[Fixed]

even in fla i have to ues pliers, to get a tire off if it's glued on well .or have really sore thumbs imho
cheers

[djg]

Use whatever works for you. I tried the tufo extreme tape once -- I was pretty psyched at first (ease of mounting, seemed secure), but had bad luck with longevity and, ultimately, a bit of a mess. YMMV, but I won't use it again.

As for cycling "science" -- right, mostly, and my own story is just that, but there ya go.

[mister]

even in fla i have to ues pliers, to get a tire off if it's glued on well .or have really sore thumbs imho
cheers

yeah, a proper gluing with mastik one and every time i have to take one off it almost has me cussing. i have honed my skills pretty nicely now and as long as i have a good stiff tire lever i'll only have some sore fingernails. no tire lever...heh, forget it.
and i've ruined basetape several times not being carefull pulling the tire off.

[pretty pony]

That just confirms what I have thought for the last few years. Tape is fine, glue is fine.
I too have been impressed by the take off strength of tape. If it is that hard to get the tire off it must be holding tight.

bye!

[mjb266]

I've got a few tubes of fast tack sitting around...I love it but wonder if anyone else is still using this stuff?

[saab2000]

even in fla i have to ues pliers, to get a tire off if it's glued on well .or have really sore thumbs imho
cheers

I once had to use a cable/wire cutters to cut a tubular enough to grasp it in order to pull it off. I know what you mean about the pliers!

[Too Tall]

I've got a few tubes of fast tack sitting around...I love it but wonder if anyone else is still using this stuff?
Of course it's sold to fix rubber gaskets to doors and such. If you are crazy enough to use it test test test. The solvent is aggressive and will probably comprimise the basetape/tyre bond. Mastik one is all you really need.

[11.4]

Egad.

There are a couple dozen assertions there.

A couple things to bear in mind: First, Tufo has improved their tape over the years it's been out. It started out somewhat glue-starved and in a narrower strip -- as a result, it sometimes didn't cover the entire width of a wider rim and a coarse unlatexed base tape could absorb so much glue that it starved the gluejoint. This is why many people applied a layer or two of glue to the rim and base tape first, then used the tape to finish it off. And by the way, over the timeframe in which these tests were conducted, virtually every glue has been reformulated so those tests are mostly invalid anyway.

Second, virtually all the research out there on tires and gluing is BS. All cycling is a compromise and any tire engineer will tell you that this is especially true of tires. If you are driving Formula 1, you can optimize one or two characteristics of a tire, but at great cost to others -- high traction costs you durability, risk of overheating, poor wet weather performance, etc. All these tests -- whether University of Kansas or Tour magazine -- examine a limited parameter or range of parameters and want you to believe that one tire, or adhesive, or procedure, is better than all others.

On the basic issue of rolling resistance: If you inflate a tubular to typical road pressures (say, 95-120 psi), the casing maintains a substantial amount of suppleness with a high range of amplitude -- i.e., it can deform significantly and with low resistance to deformation. The deformation is going to occur mostly at the road side of the tubular simply because the tire starts deforming as soon as it encounters pressure, and it takes a very stiff tubular to transfer most of the pressure to the rim side of the tire. This means any deformation amount at the rim (or the related hysteresis) isn't what people think it is. If you don't believe me, take a glued up tire at reasonable tire, put it over a ridge on a concrete pavement, and then push hard with your foot sideways against the rim. The distance that the tread deflects is greater than the distance that the sidewall deflects, which in turn is greater than any deflection on the glued surface. That proportional deflection is simply part of how a tire is designed to operate -- bigger deformations are shared by the whole tire while smaller ones are absorbed in the more robust area supported by tread.

This observation falls apart in two instances: First is when the tire is extremely stiff. Try out a Tufo Road Elite 23 mm tire and you'll see this behavior -- it's one of the stiffest tires out there. The tire doesn't deflect as much, but actually tries more to roll on the rim. The second instance involves higher pressures. Tire pressure has to correspond (even more than to rider weight) to the nature of the road surface (talk to crossers about this). If you increase inflation just a bit, you force more of the tire to flex to accommodate deflection from a road irregularity. Think what this causes: instead of just stretching or flexing a small range of fibers in your tire, you are now forcing much more of the tire to respond. It's no surprise that responding to the road irregularity absorbs more energy because so much energy is funneled into stretching more of the tire around. And at that point you'll see more engagement with the base tape and glue as well.

So as far as rolling resistance goes, if you overinflate (even by a moderately small amount) you increase rolling resistance both by forcing more of the tire to deform and by engaging the underside of the tire (closest to the rim) in part of the deformation as well. Imagine the energy you have to consume to move the tire even slightly against the adhesive bond -- it's very counterproductive. The concept of hysteresis is very misunderstood here. The base tape isn't going to "squiggle" against the glue, so it isn't a matter of hard versus soft glues (or base tapes). Rather, it's all about how readily the glue joint gives way. A Tufo base tape that provides less gluing in the 2-3 millimeters at the edge of the rim will allow that much more unimpaired deflection and reduce rolling resistance, but only because it doesn't glue the full width of the rim as well. I'm not sure I like that trade off.

As far as absolute adhesion goes, the quality of the glue job has more to do with the result than the materials used (within reason, of course). Whether you use a mix of glue and tape or just use glue, you can get a dynamite glue job if you do it right. I'm always amused at how more anally compulsive forumites are about gluing compared to pro team mechanics. Even on the track, I see top mechanics doing what would be a completely scorned glue job on this forum. I do think that there are two different paradigms for rolling tires: Among pros there's a model where at one extreme a glue job will fail but otherwise it's completely reliable. Among non-pros there's a model where at one extreme the tire is glued for keeps, and at the other you find those who just don't do a good job and roll their tires on a routine training ride. For pro mechanics it's not just convenience -- it's a matter of how many days they have to take wheels out of circulation to do a complete re-glue job. Watch a team mechanic with $3000 Mavic Io front track wheels and tires that only last a couple events, and they are replacing tires incessantly. There are so many heats that a rider may have to glue 2-3 Dugast pinks on a rim over the course of a single championship. It just won't be the perfect job that the cruising rider wants to achieve. It's a testimonial to how well a glue job does work that it does as well as it does.

This doesn't address all the assertions (some of which I sympathize with, some I don't), but at least is my point of view on these two major assertions. Several of us tried to do reproducible and properly designed experimental protocols and found that too many variables were involved, and we needed more of a compromise than stellar performance in just one parameter. So instead, we just decided to be practical and ask what really works. This was the result we came to. We're always looking at newer data and at changes in equipment, but we're trying for statistical testing with larger groups of users and then modifying one variable and then another to see what is actually significant. So far, tire pressure is significant, gluing method isn't (as long as it makes sure the tire stays glued), choice of tire is somewhat significant, and rider perception is paramount (even if entirely inaccurate).

[sspielman]

Thanks for those thoughts, 11.4....

[huey]

wow, that was great information. thanks.

[CarbonCycles]

Egad.

There are a couple dozen assertions there.

.

This post should seriously be either a sticky or in the FAQ on tires. Thanks for the education.

[IXXI]

11.4: wow. Buy that man a sticky.

Really, we can do that right? Make a whole sticky area? Other forums have that and are like the end all be all tome of The Way it Is on a given subject. (William? Your LC ever met IH8MUD?) I've seen dozens of those threads build here along the years. This would be one of them.