Tube/tyre/wheel sizes and endless punctures

p15574

I'm looking to get back on the bike after about 18 months - I gave up on it after a long period of multiple punctures every day. I had tried tubes, then tyre, but to no avail. I'm now taking another look at it and would appreciate any opinions. The punctures I used to get were all, for the most part, in exactly the same location - near the valve - and I suspect were all due to 'pinching'. I wonder have I got the right tyre and/or tube sizes, especially the latter? It's a road bike. Here are the sizes I currently have:

• Wheel: 622x19
• Tyre: Continental GatorHardshell, 23mm
• Tubes: Halfords 700 18-25c

The tyre is quite difficult to get back on after a repair (has broken a few levers) but I can live with that. The tube, however, seems way too big. If I inflate it on the wheel without the tyre on, it seems to expand hugely (see image). Any ideas?

Seaswimmer

well the tube will always look bigger when inflated outside the tyre as there is nothing to stop it expanding like a balloon.

Looking at the markings it looks to be the correct size. and if the tyre is hard to get on but goes on eventually then that is also probably the correct size.

If the tube is pinched it should burst when you inflate it.

so.

1. Are you checking the tyre all the way round on both sides to be sure its not pinching the tube before you inflate
2. Are you using a good pump and inflating to about 100psi.
3. Is your rim tape ok.

if you are getting a pinch puncture its usually 2 holes like a snakebite.

If its same spot each time examine the tyre and rim/rim tape in that area very carefully. If its outside of tube its probably something in tyre. Inside of tube (nearest rim) its probably something on the rim.

Good luck.

Carawaystick

You've the tube pumped up too much, so it'll stretch in circumference, so appear too big for the wheel

secman

Can't say enough about checking the rim tape. I changed tyres back in March and went through a spate of punctures, 7 or 8 in total.Checked for pinching, checked if something left in the tyres..wrecked my head. Eventually came to the conclusion that it had to be the tape, guy in bike shop having checked it thoroughly said it wasn't the tape. Got anther puncture and went into him again, got him to change the tapes... problem solved. A very very slight roughness on the edge of tape was the culprit.

p15574

Seaswimmer wrote: »

1. Are you checking the tyre all the way round on both sides to be sure its not pinching the tube before you inflate

Yes, I've done this very carefully, to no avail

Seaswimmer wrote: »

2. Are you using a good pump and inflating to about 100psi.

Maybe not. I've bought a good pump now though, but have yet to use it. I'll try that though. I've just lost all confidence in the bike now and wouldn't risk a commute to work on it any more, but I'll try some local cycling.

Seaswimmer wrote: »

3. Is your rim tape ok.

Not 100% sure. I've examined it, and its coverage appears a little thinner in the area the punctures are occurring in (ie it's closer to one rim so further from the other), but this didn't seem to affect punctures in the 3 or 4 years before I suddenly started getting them. I have considered getting some more though.

Seaswimmer wrote: »

if you are getting a pinch puncture its usually 2 holes like a snakebite.

If its same spot each time examine the tyre and rim/rim tape in that area very carefully. If its outside of tube its probably something in tyre. Inside of tube (nearest rim) its probably something on the rim.

Yes, I've gone over both painstakingly and can't see any anomalies or sharp elements, especially as I've replaced the tyre. As far as I recall they tended to be on the side of the tube. I can't remember if they were 'snakebite' holes either, I'm afraid (I must check the old tubes again).

T-Maxx

That tube can't possibly be the right size for that wheel.

p15574

secman wrote: »

Can't say enough about checking the rim tape. I changed tyres back in March and went through a spate of punctures, 7 or 8 in total.Checked for pinching, checked if something left in the tyres..wrecked my head. Eventually came to the conclusion that it had to be the tape, guy in bike shop having checked it thoroughly said it wasn't the tape. Got anther puncture and went into him again, got him to change the tapes... problem solved. A very very slight roughness on the edge of tape was the culprit.

OK, another vote for the tape - I'll try replacing it and pumping to the high PSI and see how that goes. The current one is kind of plastic 'shrink wrapped' onto the wheel, are the replacements still cloth ones with a buckle like I remember from years ago? Or if you get it replaced in a bike shop can they do it more professionally, like the original?

Wishbone Ash

T-Maxx wrote: »

That tube can't possibly be the right size for that wheel.

Why do you think that?

When a tube is inflated outside the tyre it expands in width and circumference as there's nothing to stop it expanding. When inflated in the tyre, the air compresses inside the tube as it's constrained.

Wishbone Ash

p15574 wrote: »

......The tyre is quite difficult to get back on after a repair (has broken a few levers) but I can live with that....

You shouldn't use levers to put the tyre back on. Use your hands only to avoid pinching the tube. There's a knack to it and it can be done with puncture resistant tyres such as Gators and Marathon Plus.

T-Maxx

Wishbone Ash wrote: »

Why do you think that?

When a tube is inflated outside the tyre it expands in width and circumference as there's nothing to stop it expanding. When inflated in the tyre, the air compresses inside the tube as it's constrained.

Of course, but something in that pic just doesn't look right to me. The tube is not much inflated at all - yet it seems way too big in circumference.

Wishbone Ash

T-Maxx wrote: »

Of course, but something in that pic just doesn't look right to me. The tube is not much inflated at all - yet it seems way too big in circumference.

Even with a few darts of the mini-pump, the circumference will increase - rubber stretches in all directions.

(Some inexperienced cyclists inflate the tube too much prior to fitting it into the tyre and then wonder why it seems too long).

BobCobb

Maybe consider changing up to 25 or 28 mm.
I was getting a lot of punctures with 23 mm, and have had none when running 25 and 28 mm since.

The 23's were also lighter racier tyres though, Schwalbe Luganos, while the wider tyres have been Schwalbe Marathon and Marathon Plus. As such, it's difficult to know whether the difference is due to the tyres being wider or because they're the heavier tougher Marathons...

tldr - if speed isn't your top priority get some Marathon tyres or another 'tough' tyre.

Wishbone Ash

BobCobb wrote: »

.... As such, it's difficult to know whether the difference is due to the tyres being wider or because they're the heavier tougher Marathons....

It ain't at all difficult to know. You can't compare widths on different tyre brands. Schwalbe Marathon Plus are about as bomb proof as tyres get so it's nothing to do with tyre width.

Seaswimmer

T-Maxx wrote: »

Of course, but something in that pic just doesn't look right to me. The tube is not much inflated at all - yet it seems way too big in circumference.

The numbers on the tube are correct though if you look carefully. 18-23 (or possibly 25)

Re rim tape.

I have used Velox rim tape since the 70's. Other people may have different preferences but I have always found it to be of high quality and easy to put on.

petethedrummer

T-Maxx wrote: »

That tube can't possibly be the right size for that wheel.

They expand when inflated with air.

AstraMonti

I had the same issues with the some Alex rims few years back. I had to use a sand paper on the rim because it had a sharp edge and I was constantly getting punctures. Run (carefully) your finger along the rim without the rim tape and see if anything protrudes.

p15574

AstraMonti wrote: »

I had the same issues with the some Alex rims few years back. I had to use a sand paper on the rim because it had a sharp edge and I was constantly getting punctures. Run (carefully) your finger along the rim without the rim tape and see if anything protrudes.

Yes, I did all that and couldn't find a problem. I'll try it again though, maybe I missed something. If not, I'll get some new tape today and give that a go first, and if that fails I might try some sanding anyway. The wheel is the only part I haven't replaced, didn't want the expense (although I've spent many times that on Luas fares since!)

If none of that works then the next choice might be between a wider tyre or the new wheel.

A part of me is attracted by the thought of a new bike altogether, it must be five years since I got this on the Cycle to Work scheme! Just would seem a bit of a waste as the bike in general is fine, I just can't trust it enough to use it...

Seaswimmer

p15574 wrote: »

Yes, I did all that and couldn't find a problem. I'll try it again though, maybe I missed something. If not, I'll get some new tape today and give that a go first, and if that fails I might try some sanding anyway. The wheel is the only part I haven't replaced, didn't want the expense (although I've spent many times that on Luas fares since!)

If none of that works then the next choice might be between a wider tyre or the new wheel.

A part of me is attracted by the thought of a new bike altogether, it must be five years since I got this on the Cycle to Work scheme! Just would seem a bit of a waste as the bike in general is fine, I just can't trust it enough to use it...

Your problems may all be due to tyre pressure. If you have never had a good pump as you said before then there is a very large chance that your tyres were always very under inflated.

Buy some good rim tape, get a pump with a pressure gauge and inflate to 100psi.

sbs2010

petethedrummer wrote: »

They expand when inflated with air.

Not that much though. The "fatness" of the tube expands loads but the circumference should not expand that much.
I'd say its a dodgy tube and is getting twisted and pinched.


OP - get a new tube. And when inflating it to put it on - just inflate barely enough for it to fill out and hold its shape.

p15574

sbs2010 wrote: »

Not that much though. The "fatness" of the tube expands loads but the circumference should not expand that much.
I'd say its a dodgy tube and is getting twisted and pinched.

OP - get a new tube. And when inflating it to put it on - just inflate barely enough for it to fill out and hold its shape.

I've bought several new tubes, all to the same effect - repeated punctures. This particular one is one of a 5-pack from Halfords, and they are all identical in packaging and when inserted into the wheel. I may have been slightly over-inflating when fitting though alright. Not as much as in the picture above, obviously!

cython

petethedrummer wrote: »

They expand when inflated with air.

I've noticed Conti tubes (and the writing on this one looks like it could also be one) being a bugger for "growing" in length when inflated, and not shrinking back properly to the circumference of the wheel in the past too. Usually results in a tube being a bit crumpled/squished into the tyre, but yet to have an issue with it in terms of punctures caused by that, once extra care is taken not to pinch the tube in that area.