Fast wheels and breakfast cereal

[cs124]

Last weekend I had the good fortune to be in Mooloolaba on vacation while the Australian Road Cycling Championships was being run.

Anyway, I got a leave pass while Mrs was at the health/beauty/pampering spa and spent a couple of hours watching the race.

Just about everyone was riding on high end carbon wheels, with one guy on ADAs. What struck me was the wierd noises coming from the ADAs. Going up the steep (14%) section of the climb these uber-wheels were making all sorts of snaps, crackles and pops.

Is this normal? What causes it?

[ergott]

The hub has small explosive charges behind the pawls that actually push you up the mountain. The only problem is you have to replace the charges every race.

[chrisroph]

Are you sure it wasn't their joints?

[Tom]

That's funny because I noticed some guy's set of Cosmic Carbones doing that on the ride this past weekend.

[ada@prorider.or]

Last weekend I had the good fortune to be in Mooloolaba on vacation while the Australian Road Cycling Championships was being run.

Anyway, I got a leave pass while Mrs was at the health/beauty/pampering spa and spent a couple of hours watching the race.

Just about everyone was riding on high end carbon wheels, with one guy on ADAs. What struck me was the wierd noises coming from the ADAs. Going up the steep (14%) section of the climb these uber-wheels were making all sorts of snaps, crackles and pops.

Is this normal? What causes it?


NO this is not normal
he sould change the setup with a steel spring

if he does not do that well what can we do about it!
cees

[ada@prorider.or]

The hub has small explosive charges behind the pawls that actually push you up the mountain. The only problem is you have to replace the charges every race.

no that not the problem
its in the rubber spring !
he should change it in the steel one
wich he appently did not do

[11.4]

Yes, a certain amount of noise like that from carbon wheels is typical. I don't think the wheels themselves actually produce it, but instead convey noise from the tires themselves. I've noticed on track tires that if a tubular has any spots that are a little short of glue so they stick and un-stick with each wheel revolution, the noise is amplified hugely by carbon. So is road noise (you get a roaring kind of noise as a disk wheel goes past, for example, and it isn't the sound of wind whistling in the spokes). Now rear road carbon wheels also have a lot of dish and have the ability to pop a bit as well against the carbon. On Cosmic Carbones it isn't necessary relevant since the spokes still seat in an aluminum rim, but with all-carbon rims those drive-side spokes can release from the carbon bed and then pop back as the rim is flexed. Building and truing those kinds of wheels is a noisy experience, and riding them can be as well, but overall I'd say it's secondary to road noise and glue noise.

(I mention glue noise because a few of us have been running a few experiments and some data collection on radial lacing, rim splitting, and on how actively mobile the glue joint really is on a whole wheel. (These are unrelated topics.) The glue joint issue addresses the actual road behavior of a tubular joint versus how Chip studied glue joints in the lab. We suspect that the joint actually breaks and rejoins incessantly, but we wonder then why old shellac was such a powerful adhesive for track wheels and whether it shouldn't be used more now if anyone can tolerate the hassle. So we're trying to find intelligent ways to demonstrate what is actually happening on the road -- or track.)

[ada@prorider.or]

Yes, a certain amount of noise like that from carbon wheels is typical. I don't think the wheels themselves actually produce it, but instead convey noise from the tires themselves. I've noticed on track tires that if a tubular has any spots that are a little short of glue so they stick and un-stick with each wheel revolution, the noise is amplified hugely by carbon. So is road noise (you get a roaring kind of noise as a disk wheel goes past, for example, and it isn't the sound of wind whistling in the spokes). Now rear road carbon wheels also have a lot of dish and have the ability to pop a bit as well against the carbon. On Cosmic Carbones it isn't necessary relevant since the spokes still seat in an aluminum rim, but with all-carbon rims those drive-side spokes can release from the carbon bed and then pop back as the rim is flexed. Building and truing those kinds of wheels is a noisy experience, and riding them can be as well, but overall I'd say it's secondary to road noise and glue noise.

(I mention glue noise because a few of us have been running a few experiments and some data collection on radial lacing, rim splitting, and on how actively mobile the glue joint really is on a whole wheel. (These are unrelated topics.) The glue joint issue addresses the actual road behavior of a tubular joint versus how Chip studied glue joints in the lab. We suspect that the joint actually breaks and rejoins incessantly, but we wonder then why old shellac was such a powerful adhesive for track wheels and whether it shouldn't be used more now if anyone can tolerate the hassle. So we're trying to find intelligent ways to demonstrate what is actually happening on the road -- or track.)


well normaly our wheels sould be very quitly
so there sould be no exsive sound
regarding tubular glue we only can say lot of people do not know how to glue their tyre properly

it certainly cannot be that their is any joint is braking
and attched right away
when notice that whith glue you can be sure that is not glued properly
and certainly just the tyre CANNOT come off as i see at some track events
if that is happening people do not glue properly!

[saab2000]

I want some of those ADA wheels.

[11.4]

Ada,

Actually, the glue joint created by a glue like Vittoria Mastik One or Continental Rim Cement is an active one that works by allowing momentary localized releases and reattachments. It also provides sufficient resistance to longitudinal tire slippage by the same mechanism. Today glues like these are used almost universally not just on the road, but also at world-cup level track events for the same reasons. There have been various attempts to attach tires with permanent adhesives such as epoxies, but they surprisingly do not work as well. The rim, tire, and the joint between them are a very dynamic structure and more extreme adhesives don't handle that kind of situation well -- they crack and fail, and when they do, the results are nonrepairable and catastrophic. As a simple example, if you've ever glued a couple pieces of leather or rubber together with crazy glue (a cyanoacrylate) and then flexed the joint after it's dry, you'll find it cracking and giving way.

We've been looking at the problem because we've been hoping to find a superior rim cement and also to figure out how to improve rim tape adhesion (if your glue joint is too strong, the rim tape simply comes off).

Anyway, Ada, what happens is that a few centimeters of tire may become partially detached, usually just on one side of the tire bed. Within a small fraction of a second, that spot will roll past the contact point with the ground (which is what will have pulled it loose) and tire pressure will pull the tire back down again. The glue joint will reform almost immediately as long as a good coat of glue exists on both tire and rim (this is why the multi-layer tedious gluing on process is so important). It's all actually part of making a reliable tire-to-rim joint.

As for some track events and the tendency of tires to come off carbon track wheels, you'll probably notice that it seems to happen a lot on Mavic Io's. This is partly because it happens most on front wheels, partly because Io's are the most popular front wheel at high-level track events, but also because of the Io's design. The tire bed is extremely narrow and does not seat many tires all that well. Mavic actually recommends a 19 mm tire, which often isn't feasible because of track surface conditions or steep bankings (where you'd end up riding on the sidewall at slow speeds and then slipping). Io's also come with a mold release compound or something like that on the tire bed that needs to be sanded off with very fine sandpaper (400 grit or higher; I suggest sanding only because nothing else seems to get it off) if you want your glue to stick well. Add general issues with gluing to carbon and it gets worse. And when you try to use Dugast latex-tread tires, you're incessantly replacing them because they may only last a couple heats. The wheels are expensive, it's hard to have enough available, and world cup race conditions aren't the best for a careful glue job.

[11.4]

By the way, Ada, I've glued up some of your wheels and never seen a noise problem, and yes, many riders do not glue adequately. However, I question whether the noise was even coming from the wheels or from a saddle, frame, or other places on the bike (or, as someone else suggested, the rider's knees). My comments were directed generally at carbon wheels. Your design is different and resolves many of the issues other carbon wheels will have.

[ada@prorider.or]

Ada,
The wheels are expensive, it's hard to have enough available, and world cup race conditions aren't the best for a careful glue job.
this is what i do not agree !!!

most of the problems is the mechanic and the people who advise a glue
mostly have know idea what theyt advise since they only see carbon and know nothing about the resin system used
!!!!!!

also the layers of glued applied is sometimes horrible
i have seen in tour and world champion ships that they tires where not glued properly
!!!!!!

[TimD]

[QUOTE=11.4]
... Io's also come with a mold release compound or something like that on the tire bed that needs to be sanded off with very fine sandpaper (400 grit or higher; I suggest sanding only because nothing else seems to get it off) if you want your glue to stick well...
/QUOTE]

I once read an interview with Leo Mehl, Goodyear's longtime director in Formula 1 and since retired. Mehl claimed that Ayrton Senna was alone in having new sets of qualifying tires lightly sanded to remove the mould release agent before the tires were mounted on his car for a qualifying run.

TimD

[ada@prorider.or]

[QUOTE=11.4]
... Io's also come with a mold release compound or something like that on the tire bed that needs to be sanded off with very fine sandpaper (400 grit or higher; I suggest sanding only because nothing else seems to get it off) if you want your glue to stick well...
/QUOTE]

I once read an interview with Leo Mehl, Goodyear's longtime director in Formula 1 and since retired. Mehl claimed that Ayrton Senna was alone in having new sets of qualifying tires lightly sanded to remove the mould release agent before the tires were mounted on his car for a qualifying run.

TimD


that depands of what kind of mould release is used
you cannot remove with sandpaper any silicon based mould release
since its to deep
then you have to grind to much !!!
better is the liquid thats remove the mould release
these are availble

[11.4]

I agree that I'd prefer using a solvent remover, but I submitted a list to Mavic (and also tested several on a broken Io wheel that I got from a national team in exchange for sharing testing results) and found most of them reacted with the resin in the wheel. They pitted the resin, left a permanent matte finish, or left permanently soft and sticky areas (the most common effect). According to Mavic, there are some Teflon-based sprays that are used on Io's. Checking with the manufacturer, they only have a surface effect (in contrast to many mold release agents) so sanding would work. And sanding certainly makes the difference between a tire that lifts right off with all the rim cement attached, and a tire that sticks pretty well. This may not be the case for other carbon rims, since they vary widely in the resins employed and how they are cured and finished. Mavic Io's aren't exactly state-of-the-art carbon chemistry, but they don't have to be to make a superb racing wheel.

[KevinK]

<snipped> We suspect that the joint actually breaks and rejoins incessantly, but we wonder then why old shellac was such a powerful adhesive for track wheels and whether it shouldn't be used more now if anyone can tolerate the hassle. So we're trying to find intelligent ways to demonstrate what is actually happening on the road -- or track.

I believe that the movement of a flexible tire/rim glue joint is a constant stretch/rebound action and not a break and rejoin. Two things bring me to this conclusion. First, if the joint continually breaks and re-adheres each rotation, then when there is a prolonged side load on the tire, as a occurs on a fast downhill curve, the breaking and re-adhering action would cause the tire to "walk" off the rim. Second, i don't believe there is an adhesive available that can withstand this type of action without loosing its stickiness after repeated cycles. Now, I know from experience that the unstick-restick action takes place, but when it does it is a result of a faulty joint, usually caused by rim or tire contamination. I don't apply glue adjecent to the valve stem (or on the rim next to the valve hole) specifically because the valve keeps the tire from seating properly in that section, and the result of putting glue in that section is the noise created by the stick-unstick action described by 11.4.

Kevin

[11.4]

Kevin,

You make a lot of interesting points. We've been trying to puzzle through some of the conflicting issues, such as why Chip Howat finds the best performance with snap-and-rejoin-favoring adhesives when the ultimate track tire adhesive always was, and still really is, shellac. Frankly, a lot of assumptions have been perforated when we look at the actual issues on a rotating wheel under various kinds of load.

The issue with your suggestion about stripping a tire on a turn would apply if a tire were skidded, and in fact that's when tires often roll. But on a sharp, steep curve, you'll still be changing the contact patch (i.e., the load point) extremely fast. If you slowed the wheel and forced one spot to carry the load for a longer time, it would give. But as the wheel spins, the tire literally moves to a new contact patch and the area that might be stressed and where the adhesive may have separated is now free to rejoin. In addition, the tensile qualities of the adhesive joint are sufficient to hold a tire on a hard turn like that. Where they give way is in an emergency braking action (a la the famous Beloki crash), where tires touch and force a skid combined with extreme lateral pressure (a la the Dajka/Tournant crash at track worlds in LA), or where the system is compromised (as in too much heat, poor joint, etc.). If we were looking at snap-and-rejoin behavior on every downhill, I can assure you nobody would be trying to ride tubulars. It just isn't a constant phenomenon with every wheel revolution. But it's not hard to generate it with a hard wheel snap at speed on a steep track banking because you can produce such a high instantaneous load on one contact patch. I actually can't think of many road situations other than touching tires where routine riding can create such a problem with a well-glued tire.

Also, the snap-and-rejoin we're talking about here is a separation of a well-glued joint at the edge of the bed that may progress half-way across the rim but shouldn't go farther before it rejoins. The issue you describe at a valve stem is definitely an annoyance with tubulars. I actually have found that a little extra gluing at the stem does a better job of avoiding it, but a bump on the inside of the tire at the valve stem is going to create a problem regardless. We usually think of tires rolled at points away from the valve stem, but in collecting samples of rolled tires in order to see what caused them, I've been surprised by the number that rolled at the stem and simply yanked it out. Very often it led to the base of the stem pulling off the base tape, which in conjunction with the obvious instant deflation (when the valve stem fails) makes for a rather harrowing situation. The latex adhesives used to glue base tapes on do tend to unzipper very fast and definitely do not recover. At that point, you have a rolled tire.