Bicycle Mechanics - Can you repair the sidewall of a tire?
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07-31-09, 07:34 AM
I have a cyclocross tire with perfectly good tread that has a 1/16" hole in the sidewall. That is just big enough for the tube to bulge out under pressure. It is a folding bead tire and the sidewalls don't appear to be reinforced in any particular manner.
Is there a way to repair the sidewall? I use this tire on my city bike so it doesn't have to be perfect or pretty.
07-31-09, 07:44 AM
Just reminded me of the old Dunlop puncture repair outfits you could buy in the 1950s. You got a yellow rectangular tin, in which were an assortment of patches of different sizes, a tube of rubber solution, a small block of French chalk and a grater to grate it with, a yellow crayon to mark the location of the puncture, some spare lengths of rubber tubing for the Woods valve, and a piece of thin canvas for repairing holes such as the one you have in the sidewall. So I'd say yes, there should be no problem if you can find a suitably strong and thin material and an appropriate adhesive to stick it to the inside of the cover, whatever that's made of. An impact adhesive probably would work best, where you'd let both parts dry to the touch, then press them together. Leave it 24 hours before refitting to gain full strength, and dust the repair with talcum powder (or French chalk).
07-31-09, 07:45 AM
There's been some threads on this previously. Many people said they patch the inside of the tire using the older style patches with glue. You need to really rough up the surface first to be sure the glue sticks.
I personally wouldn't bother. You can get new tires cheap by searching. Probikekit has Vittoria's for $35 and I think there's another 10% off that with free shipping.
07-31-09, 07:50 AM
This is true, but it illustrates perfectly the difference between America in the 21st century and England in the immediate post-war years. In those days, not only did people have to make everything last as long as possible, but you couldn't always get new tyres. My father came from Ireland to work in England during the war, and he used to have a lucrative sideline smuggling tyres and inner tubes under his trench coat whenever he went back and forth. He looked about 30 stone, and he was actually very thin.
07-31-09, 08:55 AM
Regular tube patches will work if the hole is small enough. You can also "boot" the tire with heavy nylon pack cloth inside the hole as a reinforcement.
07-31-09, 09:30 AM
Agree with above.
It is patchable. If a regular patch would take up too much room you can use part of a plastic drink bottle cut to fit. Get the edges as rounded and smooth as possible to keep it from slicing the tube. Alternatively, you could use tyvek (fedex envelopes, house wrap, etc.). It might wear after a little but it is easy enough to redo. Make sure the hole does not become a conduit for grit and such to get inside your tire.
I wouldn't race the tire but I would certainly ride it and check it before every ride. You should check your tires anyway but keep a closer eye on that particular spot.
Saying tires a cheap enough is true but it seems a waste to throw away a tire that could be made serviceable. Ya, all the arguments about safety etc. Just know that you probably have increased chance of a front tire blowout. How big or small of an increase is anyone's guess.
07-31-09, 10:31 AM
In my younger days when i couldn't afford tires, I used to patch things like this by:
Cutting a piece of denim. Spreading one side of it with rubber cement (from a patch kit). Let it get tacky. Then rough-up the tire. Spread a coat of rubber cement on the tire. Let it get tacky. Apply the denim like you would a patch. They would hold for a long time.
Two or three layers of duct tape has always worked for me. I keep a couple wraps of it around my frame pumps for side-of-the-road repairs.
07-31-09, 10:37 AM
I carry some pieces of FedEx envelope in my patch kit. Saved a few rides that way over the years. Tyvek is amazing stuff.
07-31-09, 11:31 AM
Tyvek is a great idea. I've used dollar bills on many occasions (the Linen content makes them quite strong). I'm not sure about other currencies.
1/16" tear isn't bad, though if it bulges I bet there are broken threads to either side of the hole so the tear is probably closer to 3/16". I keep an old expired (thorn proof, i.e. thick) inner tube to cut sidewall liners from.
At some point, though, a sidewall tear is too long to patch safely. Depending on orientation (and working pressure) over 5/16" it becomes iffy.
07-31-09, 12:53 PM
He looked about 30 stone, and he was actually very thin.
Wow! That's about 420 lbs. He must have looked like the Michelin Man.
07-31-09, 12:55 PM
The trick with repairing sidewalls is that you must transfer the loads across the broken fibres. Or else when you pump it up, you'll notice there'll be some twisting of the casing and a bulge. To transfer the load from one broken end of the casing-fibre to the other side, I find bridging it an equally strong material works well. And you MUST attach the material to the broken fibres in order to transfer the loads across.
Cutting up Tyvek race-numbers and gluing them in with 3M Fastak works well and won't result in decreasing the ID of the tyre, making mounting easy without having to fumble and hold boots in place. Scuff up the inner surface of the tyre with sandpaper and the Tyvek patches. Follow the instructions on the Fastak tube. I've managed to repair sidewall cuts as large as 1/2" this way with no bulges and twisting of the casing.
I just use denim patch and gorilla glue (very elastic foam glue)
basically it has to be a woven patch and glue that allows deformation.
07-31-09, 01:32 PM
Thanks very much for all the suggestions. A replacement tire is pretty inexpensive but I hate to throw away something that is 99% good; increased danger of a blow-out noted. Sounds like Tyvek plus Fastak are a good solution. All the other creative ideas like using a dollar bill wll no doubt come handy when i am someday far from home and have no other options.
Thanks for sharing your knowledge everyone!
07-31-09, 03:19 PM
BTW - You want to have multiple layers of Tyvek depending upon the size of the cut:
1/8" = 1 layer
1/4" = 2 layers
1/2" = 3 layers
Built it up like a pyramid with largest to smallest. So a 1/2" cut would have a 1" Tyvek patch 1st, then 0.9", then 0.8". The Fastak ensures that the Tyvek patch doesn't move and that loads are transferred between the casing's cut fibre ends. I've gotten thousands of extra useful miles from a tyre that many would've tossed.
07-31-09, 08:34 PM
I have a small pack of purpose made "tire boots" They are essentially large ( 2"x3") self adhesive patches that are flexible, but have little stretch. they seem to have some reinforcing grids in them. haven't used them, but they look like they would do the job.
07-31-09, 10:07 PM
Haven't seen those before but the Park ones work, also potato chip bags or energy bar wrappers, and I don't feel that glue is necessary because at 120 psi it ain't goin nowhere. 80-90 would probably hold it too. Had this happen to a new Gatorskin. Hundreds of miles (Maybe 1000+) now with that little bulge on my tire.
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