lyeinyoureye

I've tried it out as per someone's post on the forum using rubber cement (~$1+) and it seems to work well for mtb tubes using mtb tube scraps, but the mtb tube scraps don't seem to work very well on road bike tubes. Are the mtb tube scraps just too thick for the road bike tubes or can I only use scraps/rubber cement on lower pressure tubes/tires?

dscheidt

It's both a problem with the pressure (and probably you're making the patches smaller) and the material. Good quality patches (any that actually work) are made of a sandwich of different rubbers. the surface that touches the tube is unvulncanized rubber that's got fast-acting vulcanizing accelerators in it. The cement has a vulcanizing activator in it which activates the the accelerators. Combined with the free sulphur in the tubes rubber, this vulcanizes the patch to the tube, forming a permanent bond. With just a piece of tube, you're only getting the mechanical bond of the cement, which isn't very strong, particularly compared to the deformation of the tube in use.

blamp28

To what end are you doing this? I take care of our personal fleet of 7 bikes and have patched no more than three tires in the last 5 years and 10000 cumulative miles. At even twice that rate, it would take 5 more years to use up a couple of inexpensive patch kits. Have one less Starbucks drink per year and you can afford more real patches than you will ever use.

lyeinyoureye

No starbucks here and I've gone through a lot more in the way of tubes that I would like to patch thanks for the most part to goatheads. I also have a few splits I'd like to repair that don't come in patch size, so if possible I'd like to be able to use tube scraps. Based on your responses I did a bit of research and it looks like I should be OK w/ something that actually vulcanizes the patches (like from an auto parts store) as opposed to rubber cement. I'll just need to let it set longer if I'm using two pieces of tube as opposed to a patch designed to be used with it.

Thanks everyone!

dscheidt

Proper repair units are cheap, available in a range of sizes and shapes, and will actually work. 100 rema tip-top patches cost 15 or 20 bucks, 15 or 20 cents a piece. I don't know what your time is worth to you, but even if you value it at a buck an hour, it doesn't take many failed patches -- and at road bike pressures, and deflections, you'll have lots -- to make that cheap.

lyeinyoureye

Where do you people come up with these ideas? I never said I needed patches. I bought 100+ in varying sizes about five years ago and I have most of them left. The wax paper on top doesn't come off any more due to the heat but they work pretty well. What I'd like to use the tire scraps for are 4"+ long splits that I can't use the patches on. I just picked up some auto rubber cement so I'll see how that works with the tube patches in a bit.

sgrobben

Do people really patch tubes with 4"+ splits? Yikes

scroca

They are trying to tell you that you're doing it the hard way.

fietsbob

new tubes are cheap..

DGozinya

And stimulate the economy, citizen!

lyeinyoureye

Easy for you two to say! if you ain't all talk then send me a few hundred bucks and I'm sure I'll change my tune.

fietsbob

Comrade, a tube is just $5, thorn resistant, $15. or thereabouts..
tire patches have a non butyl layer that the glued surface adheres to,

vulcanized rubber can be glued together, it's all surface prep and getting the glue right.

a couple hours of labor, to limp into a bike shop then buy a new tube..

Or, you could adopt the mid war austerity, and stuff your tires with straw and rags.

blamp28

Patching a 4" long hole is false economy. Have you tried Armadillo tires from Specialized? What do other riders in your area use?

MTBerJim

My guess would be saving money for the therapy sessions.

lyeinyoureye

The only therapeutic advice I need is to check out Sheldon's site before I get the advice of the BF peanut gallery.

There's no magic vulcanization or a need to buy $50 in tubes for an $80 bike. The lighter colored rubber material on most patches is permeable to the solvents used with rubber cement, so even if the cement isn't completely dry when the patch is applied it can still cure. Butyl on butyl otoh can't do this, so the cement needs to be completely dry to use rubber scraps as patches. Thank you Sheldon and Jobst! Screw you BF nutjobs!

scroca

Like I said, you are doing it the hard way. And you think other people are nut jobs?

canopus 

Some nuts you just have to let learn the hard way. It does no good to tell them that 4" rip in a tube isn't practically patchable with another tube in a reliable fashion. Or to help them to determine why they are getting a 4" rip to begin with (In 30 years I have never seen this)

Just place your seats in the reclined position and enjoy the show...

MTBerJim

So why did you ask for it?

blamp28

WOW! is all I can say.

10 Wheels

Send me 5 tubes.. Thanks.

lyeinyoureye

What way am I doing it again?

So far so good but time will tell. Of course in 30 years you hadn't seen the information on Sheldon's page that could have answered my question, so that doesn't bode well for any experience you may have.

I hadn't seen the page yet and I figured I could get some helpful advice on the forum. Obviously I was wrong about the helpful part, but live and learn.

You're telling me! 15+ posts and not one of them helpful... You would think at least one person here would have seen the information on Sheldon's website and posted it here, but all I get is incorrect or off-topic posts.

blamp28

You are way out of line. Just because you did not like the answers you received does not mean that they were not intended to help. Mr, if you are patching tubes with holes that large you are pissing into the wind in the opinion of most here. You will of course, "live and learn" but the posters here have lived and learned so how about a little respect for the time they have put in. We all appreciate Sheldon's site and Have Read Jobst' book as well. Just because you CAN patch doesn't make it wise to do so in the larger picture. I'm glad you found what you were looking for but don't get on us here because you had to dig a little deeper to find someone who agrees with you. We are not you mothers here.

There are plenty of great resources on the web to search with a wealth of info. Man up and do a little digging before you come here and criticize. And remember low price and low cost are not necessarily the same thing. Sometimes, the cheap route costs quite a bit more. In the spirit of goodwill but only God knows why after that last post:

https://www.sheldonbrown.com/ You are aware of this one.
https://bicycletutor.com/
https://www.parktool.com/blog/repair-help
https://www.utahmountainbiking.com/fix/

LarryMelman

This is what everyone says when they want to look smart, but unfortunately it just isn't so.

Patches can be removed by heating them up. I didn't believe it till I tried it myself.

It's a very good bond, but it isn't permanent... it isn't a melting or welding or fusing together of the patch and the tube.

scroca

Like a hard headed, arrogant, dim wit from what I can tell.

SBinNYC

I've had several discussions with Jobst in RBT regarding tube patching techniques. I disagree with his technique and his explanations. Based on the criterion that a patched tube is immediately ready to ride, I claim a 90% success rate for my technique. Jobst admits that his technique requires 24 hours to cure before riding.

Regarding your specific problems. The easiest repair method is to avoid flats. A 4 inch slit is usually caused by the tire bead pressing on the tube and pinching it. That cause is 100% avoidable by taking extra care in mounting the tire. There have been several excellent detailed descriptions posted here on how to avoid this problem.
A five year old patch is probably toast. The foil side of patches is treated to react with the cold vulcanizing solution applied to the tube. This treatment will evaporate with time and heat. Most patches use a clear cellophane or plastic as the carrier on the butyl side. The only patches I've run across that used wax paper were made by a British firm: Bikit. If your patches were indeed made by Bikit, they are a lot more than 5 years old.

You can still use patches, even if you do not have a 4 inch long patch. The you can apply a patch to the outer butyl side of a patch. The butyl side requires the same preparation as a tube surface: cleaning (sanding) and applying cold vulcanizing solution. It also means you must learn how to remove the cellophane without pulling up the patch. Therefore, you may use 5 or more 1 inch round patches to completely cover a 4 inch slit.
I purposely used the term "cold vulcanizing solution" rather than cement because rubber cement is not used for applying patches. The solution is designed to work with the patch. Mix brands at your own peril.

If you insist on still trying to use an old tube, here are some hints. First, you must apply vulcanizing solution to both surfaces and let them dry completely. You should apply pressure after you apply the "patch" to the tube. This pressure should go from the inside to the outside. The purpose of this burnishing is to remove any air pockets. Rubber vulcanizes to rubber - not air.

You did not mention the size of the road tubes that don't work. I've always wrapped the tube around a flat surface (a patch kit box). I've used the box as backing when I burnish the newly applied patch. Road tubes can be extremely narrow. The patch must fit within the tube. Standard 25 mm patches are too big for many road tubes. I use 16 mm for most road tubes.

I can see a lot of problems trying to cut a 5 inch long patch that will completely cover a 4 inch slit and still fit within a flattened road tube. One suggestion would be to get a patching tube of equal size and cut out a length of the tube. I'd then cut out the section with the 4 inch slit and splice it with the patching tube section I created. This would limit the vulcanizing two areas to where the splice met the original tube. I'd think these two areas would be easier to vulcanize.

The only practical use for this solution would be, if I had a with a broken valve and another of the same size with a perfect valve but otherwise unusable e.g. a tube with a 4 inch long slit somewhere else on the tube.