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Flats, flats and more flats(11 posts)

Flats, flats and more flatsBroomwagon
Mar 18, 2002 12:41 PM
Okay, I must be doing something wrong here . . . I've been using a Silca floor pump for about 15 years and it has proven to be very dependable and easy to maintain. However, last year, I rode a little over 2000 miles and had about 12 or so flats, only one of which was caused by a piece of glass piercing the tire and puncturing the tube. The other flats were tears where the valve meets the tube. I think this is caused when I remove the Silca head from the valve after inflation. It happens in both the front and rear with about equal frequency.

What am I doing wrong? I've been inflating the tubes the same way for years and have never seen this happen until last year. So far this year, I've had three flats already. Additionally, it's not in an area where one can easily patch.

I've tried replacing the rubber gasket inside the brass chuck but that doesn't work either. Then I thought I just happened to purchase a bad batch of tubes (Performance) so I tried Michelin and Continental--same result.

Unless I push the pump head down as far as it will go, I don't get a good seal and air leaks out while pumping. Pushing it down that far makes removal that much harder.

Help! Thanks.
If you're sure that the flats are caused by tears . . .morrison
Mar 18, 2002 12:54 PM
where the valve meets the tube, you should consider getting a new pump. It would be a hell of a lot cheaper than continuing to buy new tubes.

Either that, or maybe there is a way to lube the inside of the pump head to prevent the tearing when you remove it. WARNING: I don't know if this is possible, or advisable. Check w/ lbs, or e-mail pump manufacturer.
Presta valves?tempeteKerouak
Mar 18, 2002 1:09 PM
Do you use the little screw-on rings? Some remove them. That's what they do, protect the valve stem by stabilising it.

Check the hole in the rim, but basically, from what you say, the chuck is ripping the stem off... Time for a new pump? It's cost you the diff between a new floor pump and a replacement chuck/head with all these tubes anyway...

Good luck.
I agreeMikeC
Mar 19, 2002 8:05 AM
I always carry a spare valve nut in my seat pack in case I (or someone else) doesn't have one and flats during a ride.
I had the same thinglaffeaux
Mar 18, 2002 1:19 PM
I had a MTB rim that did the same thing. I kept getting flats next to the presta valve stem. To fix it I cut a small square piece out of an old tube, and cut a norrow slot into it. I then insterted the value thorugh the small slot. This 1" square piece of old tube protected the real tube around the valve stem. I stopped the flats right away.
re: Flats, flats and more flatsPoulidor
Mar 18, 2002 2:38 PM
I also use a Silca pump and it has always been rather difficult to get the chuck off the stem after inflating the tire. It was one of those things that I got used to doing, struggle with it every time. Once, I did rip the valve while trying to get the chuck off. Recently, I saw someone post that all you need to do to get the chuck off easily is to wiggle it side to side, without pulling on it. This releases the pressure and then the chuck can be pulled off without a struggle. I tried this and it works like a charm. I have also noticed that the amount of effort it takes to remove the chuck seems to vary, I don't know whether it is due to the rubber in the chuck aging, or due to temperature/humidity fluctuations. Anyway, try the wiggle method next time and see if that helps. It has made my life easier.

re: Flats, flats and more flatsChen2
Mar 18, 2002 3:05 PM
That's what the screw-on lock ring is for, to protect the tube from movement of the stem. But also check the rim in the stem hole area. I think Performance tubes are ok. I've had good luck with them. If you have some silicone lube you could try it on the rubber inside the chuck.
re: Flats, flats and more flatscurlybike
Mar 18, 2002 5:06 PM
Make sure that the rim strip is protecting the tube at the stem hole. The tubes may be weakened by the stem hole acting like a cookie cutter. Many times Silca pumps seal real tite in the threads down on the stem. Michelin tubes don't have those threads so that is not a problem. Make sure there is no burr on the stem hole where the tube will be cut. If you are not using velox rim strip, it may be time to replace it. Is the tear in the reinforced area around the stem?
Better idea - valve extender gizmodave woof
Mar 18, 2002 7:47 PM
I got a better idea - tried it a few months ago and it's worked awsomely (that a word?)


get a 1 1/4" valve extender from your lbs, not the valve kind, the hollow tube kind. it screws onto the presta valve.

stick this valve extender in the end of your pump chuck, stick it in tight. It looks funny, but now you can screw this extender onto the presta valve - be sure to use the little o-rings inluded with the valve extender. Of course, you have to have a chuck that will twist freely in the hose or in the chuck body. I have a newer style Silca and it works for me.

I never lose air when unscrewing, it's a super tight seal and I don't rip out the rubber seal everytime I remove the chuck from the valve.


Dave Woof
Two thingsmuncher
Mar 19, 2002 6:18 AM
Make sure that you are not tightening up the lock ring on the valve stem hard before you are inflating (if you use one at all) - this can start to pull the base of the valve through the rim = puncture.

Second, keep a bit of lube on your pump head - I use a little graphite spray (GT85) - it won't stop it sealing or make it slide off when locked on, but it does make it far easier to pop off when you are done.

Thank YouBroomwagon
Mar 19, 2002 1:02 PM
I'd like to thank everyone for their suggestions. They've all been helpful. The tear is occurs right at the base of the stem so I will try Laffeaux's suggestion of placing a square patch from an old tube directly over the valve stem as an extra measure of protection.

Regarding the use or non-use of the presta valve nut, I've tried it both ways. I've also lubricated the rubber seal in the brass chuck. Maybe a combination of the patch, nut and lube will do the trick.

Thanks again for the suggestions. I appreciate your help.