What's the penny?

jeepie

I used to get loads and loads of punctures despite my bontrager hard cases but could find nothing in the tyre. I then ramped up the PSI from 100 to 120 and punctures stopped. I have subsequently found out these are called pinch flats. Phew!

Now they are back!!! I've had 3 tyres go at the valve:

Reading:

http://www.bikeradar.com/forums/viewtopic.php?t=12573414&postdays=0&postorder=asc&start=15

From MSW

I learned how to put them on properly without pinching (must have lost 4 inner tubes at the valve before the penny dropped)

OK. This is happening to me. What's the penny? [/url]

whome

Are you really asking that?

http://www.usingenglish.com/reference/i ... opped.html

jeepie

HA HA - no.... I am not asking the origins of the idiom, Whome, but thanks for your reply nonetheless.

I am asking how exactly I'm fitting my tyres incorrectly as I've the same problem as msw. The penny has dropped for msw but the penny has not dropped for me. So what's the penny? msw has changed something about the way s/he fits their inner tubes to solve the flats near the value. This is the penny. Msw has belated understood something about fitting tyres and I'd like some more experienced than me to let me know what this might be as this has long since been understood by commuters, but not by me alas.

biondino

I think he's looking for the solution to all the punctures, i.e. "the penny", which became clear to the poster, i.e. "dropped".

Bassjunkieuk

Like most things I think the only way to get tyres on with pinching the tube is to practice!

I had a spat of punctures and it got to the point where I was getting the tyres on and off with my hands! I switched over to SM+'s and they are an absolute pig to get on so I made damn sure I did it right first time!

I think the best way to avoid pinching the inner tube is to really tuck it up inside the tyre as you feed it back in. I usually start at the valve and work round. I then tuck the tyre on the inside of the rim and work it on with my hands as far as I can. Once it becomes to difficult I use tyre levers (plastic ones from halfords!) to get the last few inches in (oh er!) As I do this I'm checking to make sure I haven't got any inner tube between the rim and tyre. You can also put a tiny bit of air in the inner tube once it's tucked up inside the tyre to reduce the chances of pinching it and lifting it away from the rim.

ride_whenever

Also try to fit the tyre evenly in both directions, if you start at the valve and work round then it will have uneven tension and pull the valve to the side. If you fit the valve into the rim and push the tube into place in both directions from there it ensures an even tension and the valve should remain tight. Then fit the tyre starting from the valve in the same manner.

Don't do up the collar too tight as that can chew the valve off and finally check the valve hole for sharp edges before fitting the tube, a phillips head screwdriver can be used to bevel the edges easily.

R25 Flyer

Hi Jeepie,

I've lost a couple of tubes like this and couldn't work out what it was I was doing wrong. What I "think" I was doing wrong was over-tightening the outer nut on the Presta valve so that it was a firm fit when I went to fully inflate the tyre. I think this caused some extra pressure around the valve when I got upto ca 120 psi. I have the outer nut looser now and it hasn't happened since. Not sure if I've "cured" a problem or just had a run of bad luck with poorer quality tubes.

Any of this sound familiar? Might be worth trying.

Ectomorph

Jeepie wrote:

...Now they are back!!! I've had 3 tyres go at the valve

My first post on this excellent forum...

Yep, agree with R25, I lost 3 or 4 tubes when they let go around the valve. I'm sure I was over-tightening the locknut after inflating; I've now removed them completely & had no further problems.

What's that locknut for anyway?

biondino

Holding the valve in place while you pump it, and holding it steady when the tube isn't inflated, I guess?

jeepie

Excellent feedback. Thanks very much for that. My bike (other one) is sitting in the shed with a flat so trying out these techniques tonight! Cheers everyone!

jeepie

Quick question about the locknut (R25 and Ecto......) is that the bit the screws over the outside of the Presta valve and can be completely removed, rather than the screwy bit at the top that you seal up after pumping.... I think you are talking about the outside thing which may definitely be the issue as I've no idea what it's for.....

R25 Flyer

You got it Jeepie - the bit I always lose when changing a flat!

Ectomorph

Jeepie wrote:

Quick question about the locknut...

Yep, that's the fella. I've had no problems with attaching a pump or with the valve holding in place since I ditched them. I think 'racers' ride without them (surely not to save weight..?).

As has been mentioned, be sure to push the valve well up inside the tyre before inflating so that the slightly harder ring of rubber around the base of the valve is the right side of the bead, ie inside!

jeepie

Gotcha. Giving a whirl tonight! Fingers crossed. Thanks once again!

fossyant

Talc tube and inside of tyre. Ditch the valve stem lock nut thingy....

prj45

Key thing is to inflate the tube "just enough" before you install it IMO.