RoadWearier

Ok set out to ride to the gym. Checked the tires and they were fine. Didn't check for the ride back from the gym. Took off and WHAM! Front tire went out from under me like I hit an oil slick. Checked the front and it was flat. Anyway got the bike home and lo and behold, the stem was cut the base.

Then I remembered the seller telling me he "had them fix the rims for "normal" valves.". When I took the tire off I noticed the stem hole seemed pretty sharp so I bought some small round files and tried to smooth out the holes.

​​​​​​Unfortunately I forgot that my spare tube is a presta valve. So my questions are:

1) Can I use the presta valve tube (I'm guessing no).
2). Is the rim even safe to use? Should I put some electrical tape around the new stem to prevent this from happening again?
3) Suggestions for tubes would be good. The ones I'm seeing on Amazon that seem like they'd work are the 700c 35-45 mm size (tires are 700c x 40)

Thanks in advance.

bboy314

There are adapters, made of rubber or metal, for using presta tubes in Schraeder holes. It’s not ideal to go without, though I’ve seen it hold up before. Also seen it fail plenty of times.

RoadWearier

Ok sounds like I should just get a Schrader tube then.
Presta valves have lock rings which I've read may help prevent what happened to me. I'm assuming Schrader tubes just don't have that? That's a shame. I may put a small piece of electrical tape around the base of the stem.

DeadGrandpa

Here is a bushing (or doohickey) that I think will solve your problem. Insert from inside the rim through your enlarged valve stem hole, and it will allow a presta valve to live there with no more cutting.

https://www.jensonusa.com/Wheels-MFG...Valve-Savers-2
Also, there are some Schrader valves that have metal with threads all the way to the tube, and a little ring that screws down on it.

veganbikes

Unfortunately the seller didn't know what they were doing and just decided to go crazy. Hopefully the rim is fine and it very well could be but I would have a trusted mechanic take a look at it just to make sure and maybe before hand file the hole and remove any burrs.

If it is approved then I would put a Schrader to Presta rim adaptor like this: https://wheelsmfg.com/pss-1.html or see if your shop has one of the jam nuts that does nearly the same thing but threads on and you will be fine.

It is a shame people don't understand inner tubes and think that Schrader is some how better or they just refuse to get the correct pump (which they likely need anyway) and just learn how to pump their tires properly. A gas station is the worst place to fill a high pressure low volume bicycle tire because car tires are very low pressure and high volume.

If you do decide to stick with Schrader again still have your mechanic check it out after you have filed and removed any burrs. You shouldn't need any extra tape or anything you want a nice smooth hole that you can run your finger around because if not you will likely abrade the tube and the valve stem and cause more flats.

soyabean

Wait... folks actually DESTORY a perfect PV rim, on purpose? Just to downgrade to use SV tubes?

And this is exactly why there exists building codes.

Drago1010

There allow you you to use presta valves on shrader drilled rims.
https://www.performancebike.com/pana...saAhLmEALw_wcB

RoadWearier

Thanks all! I'll give them a try

Second question....Can I use the 25-35mm tube I have or will it not work with a 40 mm tire?

soyabean

It will balloon out and be very thin. It will work. It won't pop.

For example, for a 700x35C tire, I will choose a tube that is 700x35-50C, so the tube doesn't ned to stretch.

I will not use a 700x28-35C tube, because that smaller tube must stretch out to the 35mm.

wheelreason

When a guy (It's always a guy) walks into the shop looking for a specific width tube without a range, it makes my day...

RoadWearier

Why does it make your day?

RoadWearier

Yeah I bought some small files and tried to file it smooth. It's smoothER, but I don't really know how smooth it needs to be. I think the hardware you linked makes sense, may just go to the LBS and see if they have a set.

Aubergine 

Another option, RoadWearier . Schwalbe presta tubes have a locknut that fits into the Schrader valve hole, and thus does the same thing as the adapters other folks have mentioned.

Koyote

The photo you posted is...not funny. Especially if you know the death toll from that building collapse.

You should not post that again - anywhere.

veganbikes

It doesn't have to be super smooth but you should be able to run your finger over and around it without catching or causing pain because what will happen is it will overtime rub through so you want it somewhat smooth so it doesn't do that.

They likely have some variant of them.

urbanknight

I have run presta tubes in schrader holes at low pressure without problem, but it's not ideal. In your specific case, I'd run one of those shims/adapters just to keep the stem away from the sharp, mickey-moused edges.

noimagination

Filing the rough edges of the hole was the right thing to do (as long as you didn't go overboard and enlarge or ovalize the hole - sorry, for home mechanics one of the most common mistakes is "too much of a good thing" - I've been guilty of it in the past myself a few times).

For a quick bit of insurance: cut a piece (maybe 1" square) out of your old tube, cut a slit in it in the center, and slip that over your presta valve before you install the tube. That will help while you find a grommet to fit the hole, or buy a tube with a schrader valve. You should be OK for a while, since you're running fairly wide tires at a (presumably) relatively low pressure.

I'm not a shop mechanic, but I think that a 25 - 35 mm tube is less than ideal. In an intact rim drilled for a presta valve I wouldn't worry too much, but since you have that larger hole the tube will be stretched a bit thinner than optimal and could bulge through the gaps between the valve and the rim hole more than a larger tube. You're probably fine, but the risk is somewhat elevated with a smaller tube. You'd probably be wise just to get a tube with a schrader valve when you can.

soyabean

This is like those accidented cars that get repaired and refurbed by autobody shops.

I'll always have a nagging sickening feeling using these damaged wheelsets.

PV holes allow for narrower rims. That's why SV rims can't get too small.

RoadWearier

Yeah. These are all good suggestions. I'm going to follow them. Probably go to my lbs today and get a couple of those adapters if they have them. I'll sell the 25-35 tube or maybe make that the "just get home" spare. I went down pretty hard just in the parking lot. I thought I hit a patch of oil or leaked antifreeze. I bike in our city a lot and if that had happened in a busy street it would have been bad. Plus I hit 25-27 when I'm going downhill from my house. I would always be worried if I tried to half ass it. $6-8 is pretty cheap insurance.

​​​​​​FWIW this is the pic of the rim and stem.....






The paint scratches are from me trying to to file the hole smooth.

Aubergine 

Rim tape is designed to go over the valve hole. I'd take that crap tape out and replace it with some good quality rim tape. That alone will give you some better protection.

RoadWearier

I wondered about that, too. I thought it made more sense for the rim tape to go over/around the hole. Why is it crap tape? What should I use? Maybe for now I'll just use electrical tape or really hillbilly it up with a strip of duct tape!

Aubergine 

it's crap tape mostly because it does not cover the hole! What I would do is go to a bike shop and look for Velox cloth tape, although your shop might offer other types. I would not recommend either electrical tape, which is too flexible to provide protection, or duct tape, which will be a mess if you ever need to remove it. I once used strapping tape and regretted it when I had to refurbish that wheel . . . . .

smd4

How is it possible to get scratches on the outside of the rim, so far away from the hole, when using round files to smooth the hole?

soyabean

Easy.

A dancing drill bit.

smd4

He states clearly that the scratches are from “filing.”