A cautionary tale.

[Kev L]

Last August/September I put six spoke wheels on the Storm and had a new set of Dunlop qualifiers fitted at the same time. Since fitting them the bike has done about six hundred miles (maybe slightly more) at normal pace with a good few visits to the other side of three figures.
The Sunday before last I was out for a very brief ride due to the fact that the rear tyre deflated rapidly as I pulled off the A10. I found a mark on the centre of the carcass which I assumed was the cause of the failure so I took the wheel over to my tame local tyre man to have it fixed, left it with him on Saturday and picked it up today. The tyre had deflated again whilst awaiting my arrival, so Jeff had a look over the wheel again and found the valve had a tear in it, about a quarter of it's circumference. This would appear to have been the cause of the sudden loss of pressure and the minor puncture was just a distraction.
I had Dunlop qualifiers on the bike previously and have never had any issues with this kind of issue previously, the only difference has been the fitting of brass 90° valve extenders to allow access to the valves due to the 954 discs on the front and copious carbon fibre bits on the back.
Now I know there has been some discussion on here previously about these items but never having used them before or had anyone is my social group have issues with them they seemed like a good answer to a problem, and meant I could check the pressures without damaging the powder coat finish of the rims.
Having had this happen at relatively low speed, max of 80mph, I dread to think what would have happened if the valve had let go on a quicker ride.
This may have been aided and abetted by a weak valve, I don't know as they cut the old one out and replaced it before I had the presence of mind to have a look at it properly, but I would think long and hard before you fit these on a permanent basis.

[agentpineapple]

interesting read kev, I've run mine for 4k now without issue, but every time I have a tyre change, I will ask about the condition of the new and old valve...

[popkat]

Those extenders aren't meant to be fitted permanently, you screw them on when you check/adjust your pressures. There's a lot of pressure on the valve stem as the wheel turns and the speed is trying to bend them over, this is why bike tyre valves are the shorter 412 type. I see it often on bikes that come in to me and I always explain it to the customer and recommend they remove them, it's the same with those large novelty dust caps. The only rubber type that are ok to have on a 90 degree angle are the scooter valves, without them it's impossible to check pressures or inflate but then scooters don't go fast..

not wishing to sound judgemental but it surprises me that so many don't realise this.


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[bazzashadow]

I had the same thing happen to me and I have never used valve extenders before.
I spotted it as I was polishing the wheels,
so I had a lucky escape.
I use one of these and keep it under the seat all the time
http://www.ebay.co.uk/itm/Tyre-extensio ... 419aee33f7

[agentpineapple]

we've had this discussion before malc, and many people expressed no issues what so ever, including the 90 degree valves being used in motorsport without issue, but it's good to hear a tyre fitter/mechanics point of view....
I understand the reason why kev uses them, the 330mm discs leave little room to attach a tyre pressure gauge. me i'm just lazy, it makes life easier, but I will be asking my garage to check the valves and renew them if needs be when I have my next tyre fitted.

[popkat]

Valves do age and crack, slight cracking shouldn't be a problem if you keep an eye on it and can be an advisory on an MOT.

It's very quick and easy to check your valves, just gently push to one side and have a look.


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[Kev L]

Good to hear some alternative points of view. As I said they were the answer to a problem I had so I used them, but having experienced how quickly the tyre went and the fact that the valve was less than a year old I wouldn't repeat the experiment!
Still the good news is I'm still around and ol' blu is as magnificent as ever!

[popkat]

we've had this discussion before malc, and many people expressed no issues what so ever, including the 90 degree valves being used in motorsport without issue,

Really ! who in their right mind would race with bendy valves with a big weight on the end of them !.
Bridgeport 90 degree valves yes as they are solid and are the best thing to fit if you have limited access.

11mm ones are the correct size to replace a 412 rubber valve
http://www.demon-tweeks.co.uk/motorcycl ... yre-valves


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[agentpineapple]

those are the ones I use malc. I would never consider a rubber 90 degree valve
I assumed kev was using the same