Technical FAQ: More tubular talk
I’ve been following your recent Q&A posting about properly mounting tubular tires with great interest.
I have one question, though. You suggest that we “Let it dry overnight in a warm place (not in the cold garage), with the tire deflated, so the glue doesn’t hold it in a shrunken state.”
Shouldn’t the tire be inflated? It doesn’t make sense to me that a deflated tire wouldn’t cause the glue to set in such a way that it would “hold the tire in a shrunken state.”
Well, I was taught this way, and when you inflate a tire so it turns inside out, it often seems to decrease in circumference when you do it. Also, the tire turns inside out with the base tape off to the side rather than straight up, so one edge of the base tape will be stretched more than the other.
I’m new to tubular gluing. I recently built up some wheels on Velocity Escape rims for a tubie ‘cross setup. Just last week. After finishing the wheels I set out to glue a pair of Tufo Cubus tires. Using Continental cement I applied a layer to each rim and each base tape and let that cure overnight. The following morning I repeated on both the tires and rims. Four hours after the second coat I applied a third to the rims and mounted the tires and left them inflated overnight with the hope of racing them at Barton Park (Cross Crusade ’09 series finale). Before the race I deflated the tires and inspected the joints. The rear seemed totally solid all the way around on both sides. The front was similar but in one ~4″ section, on one side, I could push the tire away from the rim and see into the rim bed. That alone was enough to keep me racing my other wheels Sunday.
Today, I again deflated the rear and inspected it, it still appeared quite solid so I left that tire on and will ride it as is and let come what may. The front I peeled off the rim with considerable effort, for the most part the tire was a complete bear. I had to use a tire lever underneath the tire spanning across the rim to break the bond most of the way around the wheel. I know that it’s not always advisable to use tools on tubs but it seemed the only way. I noticed that in some sections the glue peeled completely off the rim leaving nothing behind, in others there was still glue on the rim. On the tire the story was similar, in spots it looked like the tire had barely been glued whereas those places that the rim was clean the tire was almost globby with glue.
So, here are my questions:
1. In your article you mention newer rims and their gluing surfaces but don’t state which is the optimal design, wider/flatter, deeper/pointier, or the Reflex with its more “featured” surface. So, what’s ideal? My understanding of contact cement and its response to different loading is minimal at best. Is a tire more secure when pulled in a direction perpendicular to the gluing surface (i.e. normal) or parallel (i.e. transverse)? If the former, then a wider/flatter rim bed would be ideal. If the latter, the deeper/pointier rim would be best. Either way, I suppose that contact area is a most important factor. Lastly, the matter of “features,” do features act like anchors or “bond sites?” Sort of like when laying tile your mud is scored rather than perfectly smooth, does it work the same way with contact cement?
2. Pertaining to my personal experience: Is it possible that the base tape was so “thirsty” that it just sucked the glue off the rim? Perhaps more likely is that there was still residue on the rim from the manufacturer that prevented proper glue adhesion (despite my sanding and cleaning with isopropyl)?
3. My current situation: The tire and rim each have a new coat of glue on them and are curing overnight. Because the rim was clean in spots, I put a second thin coat of glue onto the rim after finishing with the base tape. I only have access to glue and Tufo Standard tape, unless I special order the “Belgian” stuff. I read about your disapproval of the Tufo Extreme tape, but you make no mention of the Tufo Standard tape. Is it structurally identical to a different glue, or is it altogether different?
At this point, part of me wants to just use glue and not mess around with any of the Tufo tape, a larger part of me wants to ensure the tire stays on the wheel which means I’m willing to plop some tape down and make a sandwich.
One last question, how is it that the “Belgian” tape is structurally any different than the cloth base tape? It seems like a glue saturated base tape would do exactly what the “Belgian” tape does. I see how it adds structural integrity to the glue joint, much like rebar in concrete or even carbon fiber in epoxy, etc. Is the tape justification this: Down in the rim bed the joint is essentially rigid because the center of the base tape never needs to shift relative to the bottom of the rim bed, so why not add some “structure” to strengthen it?
1. I believe that matching the tire radius to the rim radius creates the strongest joint. So in the case of a fat cyclocross tubular (fat relative to a 23mm or smaller road racing tubular), it will be better to have the wider, flatter rim bed profile. Furthermore, I also would favor the more rounded rim edges for ’cross, since it would seem that sharper edges would increase the probability of pinch flats. I also believe that the majority of the force tearing a tire off of the rim is normal to the rim bed on the side, although there is certainly a large component parallel to the surface. Finally, if you can find any of the tubular gluing studies conducted by Chip Howat and Calvin Jones, you’ll see that they report no difference in bond strength with a roughed-up surface or a smooth surface, as long as the surfaces are completely clean of any oil or other contaminants.
2. My guess is that it’s the latter – residue on the rim.
3. I have not used the Tufo Standard tape in umpteen years and can’t remember what it was like, other than it only had backing on one side to be peeled off prior to installation. It is also no longer on the market. See the letter below for more on that.
4. Belgian tape is thinner than base tape. But Richard Nieuwhius, owner of Dugast, recommends in Simon Burney’s “ Cyclocross Training and Technique” book to split an old piece of base tape down the middle and glue it into the rim bed, although the reason he suggests it is to deal with the mismatch between rim bed curvature and tire curvature.
I thought your article was quite complete about gluing tubulars. I have been gluing tubular tires for almost 40 years now and am always interested what is being done.
I have a little insight about Tufo tape. What you used is called the Extreme tape. It is designed for extreme heat conditions. It works quite well with road tires in the summer if it is done the almost the same way you use the Belgian tape.
Tufo did make another tape that came in a yellow box that was discontinued this year. It actually said “for cyclocross” on the box. There was a rumor out that they had improved the Extreme tape and it was now good for cyclocross. I called Tufo North America and after some further research (he called Tufo in the Czech Republic), they said the Extreme tape was not for cyclocross and they were developing a new product for cyclocross.
I am relatively new to cycling and racing. I am a heavier rider and was wondering about using tubular tires. My question is, will my weight increase the chances of the tire “rolling” off the rim during hard cornering? Should I stick with clinchers?
Yes, your weight will increase the stress on the glue joint at the same cornering speed as a lighter rider.
That doesn’t mean you need to stick with clinchers, though. Tubular glue is used to attach tubulars to the rims of match-sprint tandems on the track, and both of the riders on those tandems tend to be burly sprinters at 200-plus pounds. I have seen sprint tandems roll tires, but only as a secondary result of a crash, not the cause of it.
How and where do I find this “Belgian tape” you recently mentioned in your column?
I use Tufo tape for road and track racing with few problems (except for clearing it all off the rim) but your recent article on VeloNews.com has me intrigued by this “Belgian tape.”
Our friends at Cyclocrossworld.com carry Belgian tubular tape.
You mention in your recent column about scraping the layer of latex on certain tubulars, namely Vittorias and Zipps. I frequently glue up tires for our road customers with these tires. I was under the impression that this latex layer was so that the glue didn’t soak into the cloth backing as much. I didn’t realize that it should be scraped up as much as possible before gluing. I haven’t had any issues with rolled tires as of yet, but I certainly don’t want to expose my shop to any liability if it does occur. How much risk am I running by gluing straight onto the coating as it comes from the factory?
And while I have you on the line, do you leave a dry section across from the valve stem to get a start on removing the tire in the event of a puncture? I always leave a section about three fingers wide and make sure to tell the customer. I’d like to hear your opinion on this. Most of the wheels I do this for are for race only in triathlon or road.
Bill Woodul, who was the chief team mechanic for the USCF when I was on the national team and in the resident program at the Olympic Training Center in Colorado Springs in 1980 and ‘81, taught me to do that.
At the time, Cléments were more widely raced on than Vittorias, and they, too, had that latex coating over the base tape. Before Bill taught me that, I had pulled off many a used Clément I’d been racing on, often finding that the base tape came off cleanly and all of the glue stayed on the rim. I had seen the same thing happen with many other riders.
I would have no way of giving you a quantitative level of risk to which you might be exposing yourself by not scraping the base tape prior to gluing. A lot of people glue them without scraping and have lived to tell the story.
I do not leave the unglued section. No way. I just want my tire to stay on as well as possible, and I don’t like the idea that it could get started rolling near the valve stem and then maybe carry on further into the glued section. I would rather deal with a difficult removal than a rolled tire. I would not feel this way if I were just using the tubulars for triathlons, where the likelihood of rolling a tire is low and the downside of a difficult tire removal in the case of a flat is high.
You didn’t mention the broomstick step for securing tubulars to the rim.
After getting the tire on the rim straight, you deflate the tire and set it on a broomstick that is resting on the floor. You then roll the wheel back and forth so that the broomstick presses the base tape into the rim channel, which pushes out air bubbles and promotes a better seal between tape and rim.
Laatste Ronde has a good description to better illustrate.
I used this method and no rolling after 20 races, including the mud, snow, rain and USGP Mercer peanut butter at 28psi. It’s not bad for a 6-foot-4-inch-tall, 185-pound rider.
Keep the tires on!
Last week, I mistakenly referred to a digital pressure gauge brand as an SKF. The brand is actually SKS, and the unit is called the AirChecker Duo Head. It has an illuminated digital display in bar and psi, a rotating head to fit Schrader or Presta valves, and a pressure-release button.
The drive side of a horse?
I received a lot of emails about mounting a horse and how that might relate to mounting a bike. I offer a couple of examples:
I don’t think you gave readers the whole picture with mounting and dismounting horses. The left side, or “near” side, was originally advantageous because warriors almost always carried a sword on their left sides. Mounting and/or dismounting on the horse’s right didn’t make sense because the sword could get in the way.
Part of it is just psychology: horses have to learn to accept riders on one side, the other, or both. A horse that learns to accept riders on its left side, believe it or not, won’t automatically accept riders on its right side. It’s easier to teach a horse to accept a rider on one side rather than both.
Trainers still teach horses to accept riders mounting and dismounting on their left sides for three reasons: tradition, that’s how they’ve always done it; efficiency, it makes training easier; and safety, it’s safer when riders and horses agree on which is the near side.
Indeed, all but one of the emails mentioned the use of swords – something we no longer deal with as bicyclists – and the fact that, as a reader named Henry noted “the drivetrain is on the right so that our swords don’t get tangled up in them!”
That one sword-free letter took a slightly different take:
You did not answer the question regarding why people learn to mount a horse from the left side. The answer is that most people are right handed, and therefore, left footed. You reach with your strongest hand, and, therefore, are forced to push off with the opposite foot, which over time makes that your strongest or most-skilled.
Think of any sport. In basketball, right-handed players will leap off their left foot to get highest in the air for layups and dunks. Quarterbacks are taught never to throw off the back foot, which for a right-handed thrower is the right foot.
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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.