Brady Brady
I partially rolled a tubular in Sunday's race... here is some information I came across in my efforts to lessen the likelihood of this unpleasant and potentially dangerous experience in the future:
http://www.engr.ku.edu/~kuktl/bicycle/Cusa1.pdf
A relatively quick read (written by a petroleum engineer) which compares various glues, tires, rims and presents mounting instructions determined by the authors to be superior to those offered by the glue manufacturers. Hopefully some of you will find this useful.
Mike Murray has advised me of some important caveats to this information, which I have attached below.
Brady
p.s. Regrettably, there is no mention of which glue types best adhere stickers to OBRA membership cards.
***************************************************************
***************** Mike Murray's Comments **********************
***************************************************************
I have read this before and I think it is generally correct. My personal experience is that the type of glue is less important than then the method of application. Even the glues that he measured that had a weaker bond will be good enough if applied correctly.
I would make a few edits, based on personal experience and not testing:
1) Never inflate the tire off the rim to turn it inside out, as is commonly done. Doing this places a shear force on the casing/base tape interface.
Although the base tape will still look OK I have noted that since I stopped doing this it takes longer for the tape to separate from the casing. For convenience in gluing what I do rather than inflating the tire off the rim is to stretch it over a board cut to the proper length with the base tape facing out. This way you can hold the board, or better yet, place it in a vise while applying glue.
2) Do NOT scrape the base tape with a straight edge. Most tires have a coating of latex over the casing and base tape. The function of the latex is to keep water and glue from intruding into the casing and the casing/base tape interface. If you scrap the base tape you are removing latex which will make it more likely that the rim glue will attack the casing/base tape glue.
3) Some suggest rolling the uninflated tire over a broomstick lengthwise to press the tire to the rim. Another thing to do is seriously overinflate the tire after mounting. Increased pressure pushes the tire on the rim tighter.
4) Don't use much glue. The layers should be as thin as possible.
Personally what I do is coat both tire and rim and let dry, generally only for a few hours. I then coat the tire with a thin coat and let dry until tacky to mount it. If you let it dry too much you will not be able to move it around to get it straight, Don't worry about getting the tire completely straight. These glues are pressure adhesives so the tire is going to squirm around. As you ride the tire will tend to be pushed into a centered position.
5) An acid brush works great for application but it is a pain to find them.
A plastic bag over your finger works just as well to spread the glue out thinly. Plastic bags are a lot easier to find.
Cyclocross tires are a particular challenge. The bigger tire has more leverage to push it off the rim. In addition the lower air pressure provides less force to keep it on. When mountain bikes first came out there were some manufacturers that made tubular mountain bike tires. These were given up as unworkable since the big tire would pry itself off the rim. Off road tires also often end up sliding sideways, something that rarely happens on the road or track. When cornering on the road there is actually very little shear force on the tire/rim interface since the force is radially along the wheel. Sliding sideways changes all this and produces more shear forces. The additional problem in cross is that water and dirt work their way into the glue interfaces.
What I would like to see someone do is to look at using hard glues rather than pressure adhesives to mount tires. We use pressure adhesives because back in the old days you needed to be able to remove the tire and put a new one on the rim and have it stick when you had a flat when you were out on a ride. Since virtually no one is using tubular for training any longer this is a moot point. Back in the day people used to shellac tires to the rim for track racing. A hard glue like shellac or epoxy would make more sense because you could get a stronger bond and you would not have tire squirm.
The tire squirm contributes to roiling resistance so a hard glued tire should be faster, though likely imperceptibly so.
Mike Murray