Bumpy Front Tire
 

Hello, newbie to road riding and this forum so pardon my ignorance. I bought an entry level bike about 4 months ago and enjoy riding it. I had my first flat recently and replaced the tube with one that has a Presta valve as opposed to the Schrader. Since I've installed it I've ridden several times and I notice a "bump" in the front tire. It seems to be revolution dependent. Through a bit of research I've learned that I should've installed an adaptor for the Presta valve. Could this be the cause of the rough ride? Thanks in advance for any advice.

You should never feel a bump at the valve.

I'd slowly rotate the tire on the wheel and see if you can see where the tire is actually bumping.

A few possibilities come to mind.

1. Flat spot in the tire from skidding.
2. Tire bead not seated evenly on the rim for one reason or another.
3. Tire seated on top of the valve, rather than pushing the valve up and around the tire beads.

I've had bumps form where there is weakness in the tire. Eventually that leads to blown tube along with replacing tire.

Careful! That bump will likely turn into a blowout. Not fun at speed. Re-install & check everything twice. Might have a bad tire too. You should never feel a bump in a tire.

I've never found any benefit from Schräder-to-Presta adapters other than that reduce the amount of stuff getting into the rim via the gap around the valve.
even assuming the normally expected usefulness of the adapters, it's hugely unlikely that it would have anything to do with your issue.
I'd be more inclined to suspect that you have the reinforced part around the valve trapped underneath the bead. After having installed a tube, but before inflating, make sure the valve is free to move inside the tire.
Failing that, some tires are a bit tight, and will need some encouragement to settle out to the hooked edge evenly all around.
And, from afar, I can't entirely rule out that your tire is damaged or defect.

Like # 4, the tire bead may not be seated properly. let the air out push the stem in and let the tire seat properly.

double check your work.




Schwalbe P/V tubes include a stepped ring nut on the stem to center it in a S/V Hole..




'/,

+1 to inspect & re-install. Is your valve cockeyed? If a presta tube in a schrader rim is free to rotate, it can lead to a bulge near the valve since the valve stem is more likely to move around in the bigger valve hole. It's also possible your tire isn't seated properly on the rim, which is a blow-out hazard as noted above. You should probably be able to see/locate the bulge. Inspect to see if there is any damage to your tire.

A presta tube in a schrader rim can start to press out of the valve hole, causing the edge of the valve hole to cut into the tube. This will often lead to a flat over time, especially at higher pressures. I know this because...

http://i850.photobucket.com/albums/a...ps2xcbixfw.jpg

Pretsa tubes, good/Conti anyway, come with a valve stem nut that will adapt the presta stem to a schrader drilled rim.

We haven't heard back from the OP yet. Hopefully he didn't have a bad blowout.

One thing that did cause one of my tires to bump. I had a pretty big gash in the tire, so I decided to install one of those Park boots. It caused a nasty "bump". So, I cut the boot in half and put it back in, and it worked fine, up until it worked through the tube, got a hole wore through it, and eventually it disintegrated.

Also, make sure the wheel is true without significant hops.

Thanks for all the replies. Haven't had time to look at it since i posted but I'll be taking it down today and seeing what I see. I'll keep y'all posted. Thanks again!

Sorry for the delay in posting results. Today was the first chance I've had to ride, what with college football Saturday, beer, etc...I installed a new tube with a Schrader valve and she rides smooth. Thanks for all the advice!

Glad it is working better.

But, I still think that the issue was not Presta/Schrader, but probably something that occurred during installation.

However, smooth is good, and use what you're comfortable with.

Yes, the issue was that he had not properly seated the bead. When he replaced the tube, he did.

Depends on where you're putting the valve stem nut. And what you expect an "adapter" to do for you.


Keep in mind that the tube is pushing against the tire side face of the rim.
Most people put the valve nut - or their preferred choice of Schräder/Presta adapters - on the hubside face of the rim.
Where, on a double wall rim, it won't do a thing for protecting the tube against damage.


An adapter used on the hubside face of a double wall rim gives some protection against dirt or water entering the rim via the gap around the valve stem, that's all.


Putting a valve nut at the base of the valve stem would "work" as a Schräder/Presta adapter, but comes with its own issue of forcing the tube to follow a rather sharp contour when it transitions from valve stem nut down to rim strip.
Some think it helps, some don't.

If the tire slides on the rim dragging the tube with it, trying to anchor it by the stem is a very marginal fix.


The amount of retention available before failure seems to be pretty much the same regardless if the valve is held perpendicular or slanted.


I'd be more inclined to believe that people with poor inflation technique when using hand pumps might benefit from more firmly seated valve stems.



Any adapter used at the hubside face of the rim wouldn't do anything to protect against that.


What's "higher pressures" for you?
According to my pump, I run my commuter on 6 Bar, and never had that issue.
It's possible I suppose that my choice of rim tape and my habit of poking a rather narrow hole in it is what's been saving me from that kind of damage.
But that theory is getting shaky, since I've switched to using banding tape, which doesn't resist being pushed apart as well as fabric tapes, and I'm still not getting that kind of damage.


Besides, there's probably some spread in how the valve bases are reinforced and the size of the valve hole.