Long time rider, first time flat fixer
June 4, 2011 8:34 AM   Subscribe

Cycling filter: Is it a big deal if my presta valve doesn't go through the rim exactly perpendicularly?

So it's a bit embarrassing for me to admit this, but this morning I changed a flat on my bike for the first time. After about an hour and a half, I finally had the tube back under the tire, and managed even to get the tire back on without the use of tire levers.

But, as I as refilling it (slowly, to make sure that there's no flat spots / bulges, natch), I noticed that the valve is slightly off center compared to the hole through the rim, and it's probably sticking out from the rim at around a 75-80 degree angle rather than the 90 that it should be. Is that something that's going to be a big problem? Should I deflate the tire and start over? Or will everything be fine?
posted by thecaddy to Travel & Transportation (13 answers total)
off-center? as in the hole is bigger than just large enought to fit the valve through?
Are you sure this rim is meant to be used with presta valves?
posted by HFSH at 8:46 AM on June 4, 2011

Do you have a threaded nut that goes around the presta valve and screws flush to the rim? That usually keeps it straight.

If not, I almost guarantee that once you inflate it up to pressure, the valve will straighten out.

Don't worry, changing a flat gets SO much easier the more you do it.
posted by Think_Long at 8:46 AM on June 4, 2011 [2 favorites]

Presta valves are more likely to break than Schraeder valves, in my experience. If you have the time to adjust it, you really might as well; it's good practice. The more flats you fix, the easier it will be to fix them.

On the other hand, if it's just going to make you frustrated (because you've already worked on this for an hour and a half), you're probably fine. Personally, I'd readjust it. It's probably ok though.

The worst thing that can possibly happen is your valve snaps off and you have to get a new tube - you'll have to be the judge as to how you feel about the worst-case scenario.

And congratulations! You fixed your first flat, and got the tire back on with no levers! I will admit, I have cheated and used levers to get the tires back on for years, so high five.
posted by aniola at 8:48 AM on June 4, 2011

I'd probably try deflating it, then reinflating it. It might not go off-centre the second time. This problem certainly can lead to flats, so I guess the answer to the question depends on how important to you it is not to get a flat while you're out riding.

On preview: seconding tightening the nut before you inflate the tyre.
posted by mattn at 8:49 AM on June 4, 2011

If you're changing the tube by the side of the road, I'd say everything will probably be fine.

If you're at home with an air compressor or a floor pump or something, I'd say deflate and start over.
posted by box at 8:49 AM on June 4, 2011 [1 favorite]

P.S. It looks like there is a community bike collective in your area. (via) Check them out if you haven't already! The best way to get better at things like fixing flats is by volunteering at a place like this.
posted by aniola at 8:53 AM on June 4, 2011

Incidentally, I just saw this blogpost with an interesting suggestion that not fastening the valve with a nut will help indicate an underinflated tire by means of a tilting valve.

But honestly, It feels wrong to me to leave something unsecured when it has the damn screwthreads right there.

(More directly related to you question, if the hole in your rim is not to big for a presta valve (you can get adapters for that), your tire is probably rotated a bit. Not really a big deal.)
posted by HFSH at 9:01 AM on June 4, 2011

Incidentally, the easy way to fix this is to let all the air out, and just rotate the tire on the rim. Grab a few spokes with one hand, right up against the rim, and hold the tire in your other, and just pull---the entire tire/tube assembly should slide around the rim. Then you can re-inflate.
posted by d. z. wang at 9:27 AM on June 4, 2011

For me, invariably when I install a new tube and the presta valve stem is slightly out of whack (i.e. isn't completely perpendicular to the rim) and I get a flat down the road, it's usually because the seal between the presta valve stem and the tube has weakened and has a small leak.

I would probably reinstall the tube.
posted by scalespace at 12:45 PM on June 4, 2011

If it is at a non-perpendicular angle, the valve stem is pinched against the rim on one side. This unnecessarily puts mechanical stress on the stem at that point.

So if you go over a bump, you're more likely to cause that pinch to turn into a hole, causing a flat.

Deflate the tube and try to reseat the stem. If that doesn't work, remove the tire and adjust. That's what I would do anyway, since it sucks getting a flat in the middle of a ride. It's a few more minutes of work for hours less walking home.
posted by Blazecock Pileon at 1:30 PM on June 4, 2011

As a frequent bike repair man, an off-kilter valve is something I'd fix. You're just asking for another flat.
posted by chairface at 8:54 PM on June 4, 2011

If you slightly inflate the tube (enough for it to hold its shape) before inserting under the tire and you start inserting the tire by seating the valve in its hole, you shouldn't have to ever deal with a wonky valve.

The threaded collar is unnecessary and can be left off. If the valve is properly seated against the rim when the tube is inflated it's serving no purpose. Some brands of tube don't even thread the valve stem and hence don't provide a collar. All the collar does is slow down the tube changing process when you get a flat out on the road.
posted by normy at 11:59 AM on June 6, 2011

I went back and reseated the tire, and rode to work today with no issue. So thanks everyone!

(Aniola--I love Cville Bikes, and would have headed over there, but I moved to another city recently and haven't gotten around to changing my profile yet. Anyone in Cville who might find this in the future is totally encouraged to go there.)
posted by thecaddy at 5:32 PM on June 6, 2011

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