Puncture when braking

[Andrew_Culture]

This kind of follows on from my thread about my tyres being knacked but this problem has been a real head scratcher.

Why I brake on a steep hill (so brakes on for a while to slow down rather than sharp braking) I get a puncture on my front tyre. Here's what I have tried so far.

Each time I fix the puncture I take the tyre off and check it very carefully.
The puncture is in a different place each time.
The rim tape is quite new and there are no spoke heads poking through.
There are no loose spokes.
The punctures are an instant flat rather than a slow puncture.
I have taken off the brake blocks (which are a bit worn) and cleaned them with a toothbrush.
There is nothing in the, erm, crotch of the front forks that shouldn't be there and that hasn't always been there.
I have fitted crud catcher mk2 mudguards a few days ago but apart from the brushes I can't see anything that contacts the wheel.
There is no sidewall damage that I can find.
I have repositioned the brake blocks to ensure they are only contacting the rim and not the tyre.
I have a replacement tyre but am concerned that I will damage it if I don't resolve this problem before fitting it.

 

[martint235]

Are you putting the tyre on in the same place each time? ie with the brand over the valve? It's just that you say the puncture is in a different place each time. My guess would be something very tiny in the tyre, go through it really carefully with something like a Hope 1 in your hand.

I don't think braking is an issue unless it's this that makes the tiny thing poke through the tyre. I did hear once about TdF riders puncturing because of the heat generated coming down mountains but I'm guessing that's not happening in Suffolk.

 

[summerdays]

Just before I remove a tyre I normally mark the tyre where the valve is, and then once I've found the puncture I line up the tyre to know where I'm meant to be looking. (I forgot last time and it took ages to find the glass). I seem to remember someone on here suggesting lining up the logo on the tyre with the value for the same reason when putting the tyre on.

Edit: just seen Martin is suggesting the logo thing too

 

[Rohloff_Brompton_Rider]

Trapped tube, the heat from braking expands the tube and then "jacks" the tyre over the rim and then kaboom!

Once the tyre is back on, check both sides by pulling the tyre back to expose the inside of the rim. I go from valve



Edit: if this is the case the tube will have a serrated gash rather than pin prick hole

 

[biggs682]

and who said cycling was easy .

this sort of thing can be so frustrating

 

[HLaB]

I'm just back from the pub so apology if this is garbage Andrew, do your tubes have two p'ture holes, if so its snake bites (aka pinch p'tures); increasing your psi's or smoother braking may help.

 

[growingvegetables]

Are you putting the tyre on in the same place each time? ie with the brand over the valve?

Sorry - it's a digression. But thanks for that - I'd rather know about it from on here than in real life.

Edited to add - hawthorn? I'd one a while back, well embedded in the tyre, and the pointy tip was broken ... but not broken off. Running my fingers round inside the tyre one way, and the broken tip laid flat - I never felt it. Took me 3-4 punctures to get frustrated and run my fingers BOTH ways one time. Lo and behold, up the ****** popped.

 

[Andrew_Culture]

Thanks all, I posted this then went away to a music festival in Camber, and apparently mobile Internet hasn't reached Camber if you're an O2 customer.

I shall follow your suggestions and report back.

 

[Andrew_Culture]

Having replaced the inner tube, tyre, wheel and brake blocks I can now use my front brake without getting a puncture!

 

[martint235]

Having replaced the inner tube, tyre, wheel and brake blocks I can now use my front brake without getting a puncture!

So all that's left from the old setup is the calipers?

 

[Andrew_Culture]

So all that's left from the old setup is the calipers?

And the forks!

Actually and the Crudcatchers some kind soul gave me, I was really hoping not to have to take them off!