Cycling UK Forum

Having problems mending punctures any tips - currently clean tube check tyre but find that a slow puncture often results- i use PowerBond glue which generally works very well.

I also place washer larger than patch over it and clamp it together.

Any advice would be appreciated

I don't know much about 'powerbond glue' but I do know that there are very few adhesives that will give a joint that is both airtight and flexible enough for use in a cycle tyre.

I would advise that you use proper patches and proper rubber solution, sold for the purpose.

Rema Tip-Top and Cure-C-cure are good brands, but in truth even stuff from the pound shop works OK if you have good technique.

cheers

I think Powerbond is a cyanoacrylate glue. It is not suitable for gluing "oily" plastics - polythene etc - and I suspect inner tubes might also be classed as "oily" as well. Also patches and inner tubes need to be able to stretch and I don't think cyanocrylate gives that sort of bond.

As Brucey says use the right product - it's cheap enough. The usual way is to apply the rubber solution (glue) and then let it dry completely before applying the patch. It's a contact adhesive. You are basically bonding rubber to rubber with rubber!!

I haven't bothered to repair tubes for years. They are cheap and disposable, just chuck them in the bin.

Yeah I'd use the proper stuff - puncture repair kit uses vulcanising solution, which I think is more akin to welding than gluing - the material of the patch and the tube meld together.

There are a few things you need to do to ensure a good patch job. Firstly the solution must not be too old- once the tube has been opened it might only last a few months before going milky looking and 'off', less likely to stick properly. For this reason it makes sense to save a few patch jobs up, otherwise it can be as expensive as buying new tubes if you need new solution every time.

Draw a big circle around the hole with a biro, and draw some cross-hairs outside the circle, so you can be sure once you've sanded the area and can't see the hole anymore that you're sticking the patch dead centre over it.

Sanding the area is as much to clean it as anything else, so don't touch the area you are going to patch once you've sanded it, and certainly not after you've spread the solution on it, don't poke at it to see if it's dry etc. Similarly don't touch the business side of the patch when you've peeled the foil backing off. If you do either you're introducing a layer of 'finger oil' in between the surfaces that need to be fused together.

You want a thin layer of solution, evenly covering an area that must be bigger than the patch that you're gonna stick on it so that none of the edges will peel. Don't put the solution on and then go over it a load of times trying to get it even, you'll ruin it. Just put a blob and spread it with a couple of swipes, then leave it.

If you splurge it on it's unlikely to dry in the time you leave it, and it needs to look dry before you put the patch on. This takes 4 or 5 minutes - ignore instructions that tell you otherwise. If you put the patch on when it still looks wet or is tacky it's unlikely to stick properly.

Knead the patch on to the tube with your thumbnail from the centre to the edges of the patch, no need to clamp it and leave it, but make sure that you treat the whole area of the patch thoroughly in this way. Peel the backing off the patch from the centre outward so that you're not peeling the edge of the patch up, the backing usually has a split in the middle of the patch for this purpose, if it doesn't you can pinch the patched area in half and the plastic backing film will split in the middle for you.

Don't inflate the tube too much to check if it's worked - leave this for when it's back inside and supported by the tyre carcass. Don't forget to chalk the whole area you've spread solution on so that it doesn't get stuck to the inside of the tyre (that's what the grating area on the box is for), and don't forget to thoroughly check the tyre/rim tape etc for all causes of the puncture.

If you do all of these steps properly it will work without leaking.

jezer wrote:I haven't bothered to repair tubes for years. They are cheap and disposable, just chuck them in the bin.

Thanks to people like you I've got a few I've gleaned from the roadside.
How on earth you can buy a tube for the same price as a patch and a spot of rubber solution i don't know.

Despite it being to my advantage I really do wish cyclists would take their old tube home or put it in a bin. It would save me having to keep stopping. [emoji1]

I hasten to add I've never left an old tube by the roadside. I always take them home for disposal, or to cut off bits to protect my car boot lid from the bike rack attachments, lol

I know it's a bit of a pain to get around to fixing punctures, but it's a bit wasteful to chuck them away just because of one puncture! I know loads of people who do it though. By the way can anyone comfirm that the 'talc' that billows out of inner tubes is in fact ground up fish bones? (hence the fishy smell) I've heard that because inner tubes are made in Thailand/Indonesia etc and fish bones is a by product of large fishing industries, that that's what is used in place of talc. Makes sense but I don't know if it's true.

There is no logic to mending punctures these days ... unless on a tour out in the wilds. Someone would typically only mend punctures if they wanted an excuse to tinker around in the shed for a while.

welcome to the throwaway society....

Needless to say, I couldn't disagree more.

cheers

Brucey

most of my...er.....yes...those recently have been a split at the joint between the tube and the valve. they give the feeling of a slow p for about a week then i cotton on, investigate and find the little split.

nothing can be done with these i take it?

I have taken valves of the bolt-in type (remember those?) and fitted them to tubes where a vulcanised valve has failed.

If you are having problems of that type it can mean that the tubes are badly made, but it can also be because the rim has a large hole in the inner wall and there is no ferrule fitted to support it properly.

cheers

I normally mend mine at the side of the road, often without removing the wheel. I have to find out where the thorn/nail etc is to prevent another puncture anyway. When I've done that it only takes a short time to patch the tube - saves the faff of dealing with it when I get home. (I recently rode with someone who had obviously forgotten the last bit and had since been riding with a punctured spare!)

Thanks for all the tips - I only started usoing PB after trying aforementioned glues.

I think it probably is suitable its v. frustrating as I've tried all the tips PB used to work superbly 9 and much better than I thought it would).

I think what is happening is that the patch is leaking a bubble at a time so it deflates.

Has anyone tried patching an inflated tube - would the patch not fit more easily / securely to an inflated tube( in the sense that I think its the pressure of inflation that forces out a bubble one by one)?

Also I've mended small splits at t he base of the valve stem previously- punch a hole in a patch slip it down the stem and secure it - I was surprised it worked but it did

I think you may be trying to use an adhesive that is simply not flexible enough for use in a tyre. If so it is bound to fail when you actually ride on it.

BTW if you are using a tube that is rather narrow for the size of tyre that you have, this does strain the tube and the patch more than normal.

If you are able to apply the patch when the tube is rounded out (usually only possible if the hole is small and the bond is instant, as with rubber solution) then the strain on the patch is somewhat less.

Note that if you failed previously using proper materials, this wouldn't have been an accident. Almost certainly you were not doing it right. Changing to an adhesive that is not really meant for this application is extremely unlikely to improve matters.

I'd suggest that you get some proper materials for the job and learn how to do the job properly.

cheers