Bicycle Mechanics - Drilling the rims...

Hello everyone,

I've been thinking of changing my bikes tubes from Presta to Schreider (car type), but have hesitated since the Schreider valve is slightly thicker than the Presta-sized hole in the 700c rims, and I would need to enlarge the hole to accommodate it.

Would there be any problems like weakening the rims (Clydesdale here)?

Hello everyone,

I've been thinking of changing my bikes tubes from Presta to Schreider (car type), but have hesitated since the Schreider valve is slightly thicker than the Presta-sized hole in the 700c rims, and I would need to enlarge the hole to accommodate it.

Would there be any problems like weakening the rims (Clydesdale here)?

I drilled out my 29er rims to fit schrader valves and saw no issues.

Clyde here as well.

I'd imagine it'd depend on how wide the rims are. 29er rims have more room between the walls to drill a larger hole and still have enough metal for structural support. A narrow 700c rim might not have as much.

done all the time .. a tapered hand reamer is the best tool,
as would be some way to smooth the edges so it won't cut the Tube ..

The easiest way to know for sure is to see if the maker offers that rim for SV. If they can drill it, so can you.

If you have narrow rims, and the maker doesn't off SV you can still drill it and strength won't suffer, but there's another issue. Narrow rims have narrow clearance between the inside walls of the tire seats. Add the thickness of the tire bead (twice) and that gap gets narrower yet. Some narrow rim/tire combinations don't leave enough room for the wider Shrader valve, and using one will cause seating problems.

If I'm not mistaken, my rims are Rigida X-Star 17 with Michelin 700c x 38 tires... if that helps!

If they're x-star 17s there are a few considerations.

1- clearance between the insides of the tire beads
2- is the width of the flat zone between on the inside of the rim, wide enough? measure this.
3- is there enough room between the two inner walls of the side bracing (see cross section of the rim). Most likely there is, and if the spoke holes are wider than an SV there certainly is.

You can check for the second and third condition easily enough, or confirm by seeing id Rigida offers this for SV. But the tire clearance issue remains. Deflate your tire and push it across so to see if the remaining gao (that used to be in the middle) is wide enough for the SV. If it's tight, you're probably better off staying with PV because SV will make mounting harder.

Stupid question, why do you want to go to SV in the first place? PV is better suited to bicycles, and usually easier to hand pump.

Stupid question, why do you want to go to SV in the first place? PV is better suited to bicycles, and usually easier to hand pump.

For the same reason most people do - because Presta valves are awful. The core snaps off, the body snaps off, they suck. Schrader has a protected valve core and a thicker body that is often flexible.

For the same reason most people do - because Presta valves are awful. The core snaps off, the body snaps off, they suck. Schrader has a protected valve core and a thicker body that is often flexible.

Please don't take offense, but I think the problem is that no one ever showed you the care and feeding of Presta Valves. if you were to poll this forum, or any group of experienced cyclists they'd tell you that they prefer PV for a number of reasons.

Yes, it's easy to break the outer stem off. But it's just as easy not to, and doesn't matter either way. The "flexible" body you're seeing on some SVs is a design defect where in the brass (or steel) body of the valve is too short and ends in the rubber base cone outside of the rim. Countless cyclists have been stranded when these snap off while pumping on the road.

Obviously it's your bike and strictly your decision which valves you prefer.

Thanks! I'll look into the dimensions tomorrow morning FB.
As for Presta vs. Schraeder (finally spelled it correctly!), it's more a matter of convenience since I'm surrounded by gas stations near my home and work which of course only have Schrader valves on their pumps. Although what @when said does trouble me a bit since I broke the stem of a Presta valve a few weeks ago, although it was a stupid mistake on my part.

Thanks! I'll look into the dimensions tomorrow morning FB.
As for Presta vs. Schraeder (finally spelled it correctly!), it's more a matter of convenience since I'm surrounded by gas stations near my home and work which of course only have Schrader valves on their pumps.

I know this is too simple, but have you considered simply leaving a PV adapter on the tubes? A decent O-ring adapter (most are today) makes a good seal and can be left on permanently (unless you have tubulars, aka sewups).

I ride tubulars and have been carrying a brass adapter on my FD mounting screw for 45 years in case I break a pump, or simply decide to benefit from the convenience of a friendly gas station. However with many stations now charging for air, I usually pass on that option, plus it's rare that I'd get a flat in such a convenient place. My bike hates how I abuse it and only flats in the rain, dark, cold, or a lousy place to change a tire, or when I'm in a rush, or sometimes all five.

Get a few pv/sv adapters, 1-2 bucks, most bike shops have a bowl full at the register. And/or get a co2 inflator or a pump. I have never pulled off a pv. But there is nothing worse than when a sv pulls off the tube after you have it pumped up.

There is an adapter that screws on the PV so that you can use a regular gas station air supply You only need one as it can be moved from wheel to wheel. This way you can save a lot of potential issues. Good luck.

For the same reason most people do - because Presta valves are awful. The core snaps off, the body snaps off, they suck. Schrader has a protected valve core and a thicker body that is often flexible.

I've been riding 40 years and have never had any of these things happen, I've never seen this happen to anyone I was with, have never heard anyone else I ride with ever say anything about this. Could you be doing something wrong?

I actually have a couple of these adapters, but they never really seems to work correctly, especially at gas stations which have the portable pumps (thankfully the air's still free here in Greece!).

The reason I would prefer a Schraeder valve is that its easier for me to check the tire pressure at a local gas station than it is at home which is an apartment building where I can't leave my foot pump near the bike. It's not critical for me to change to Schraeder, but it would make a life a bit easier since I commute every day.

On another note (still on this topic)... my tires need replenishing (topping up 5-10 psi) every few days or a week at best. Is there anything I can do/purchase which would help keep them inflated at the proper psi (72 psi) longer?

Pure nitrogen leaks out slower than the O2/N2 mix that is air- oxygen is slightly more soluble in rubber than nitrogen. Maybe sulphur hexaflouride? It's a big dense non-reactive gas that may have trouble going through rubber. Might be hard to obtain, tho. Also, "heavy-duty" inner tubes are less permeable than lighter ones strictly from their thickness. But no, any gas you put in your tire will come out eventually.

I'd sooner get an adaptor and a tire gauge. They can be found in "bicycle pressure" ranges and don't weigh much. Best option would be to get a good mini-pump that has a gauge on it, like the Topeak Road Morph G. You could then top off the tires or check the pressure anywhere, without drilling your rims! :thumb:

I actually have a couple of these adapters, but they never really seems to work correctly, especially at gas stations which have the portable pumps (thankfully the air's still free here in Greece!).

The reason I would prefer a Schraeder valve is that its easier for me to check the tire pressure at a local gas station than it is at home which is an apartment building where I can't leave my foot pump near the bike. It's not critical for me to change to Schraeder, but it would make a life a bit easier since I commute every day.

On another note (still on this topic)... my tires need replenishing (topping up 5-10 psi) every few days or a week at best. Is there anything I can do/purchase which would help keep them inflated at the proper psi (72 psi) longer?

Yep, the adapters work sometimes but not always. They're also a pain to use unless you just leave the presta nut unscrewed all the time. Tubes meant for larger tires will help keep the air in, as they stretch less when inflated. If you have a 700x38 tire you could try a 40-45 tube. Schraeder valves also hold pressure better!

I've never snapped off a presta valve due to improper pumping but I've had at least 4 or 5 simply refuse to open. The stupid things get sticky and no matter how you 'burp' them they will not come free. I've never had a Schraeder valve fail on a bicycle or a car.

Please don't take offense, but I think the problem is that no one ever showed you the care and feeding of Presta Valves. if you were to poll this forum, or any group of experienced cyclists they'd tell you that they prefer PV for a number of reasons.

Yes, it's easy to break the outer stem off. But it's just as easy not to, and doesn't matter either way. The "flexible" body you're seeing on some SVs is a design defect where in the brass (or steel) body of the valve is too short and ends in the rubber base cone outside of the rim. Countless cyclists have been stranded when these snap off while pumping on the road.



I've raced, toured, and commuted on MTB and road bikes for decades. I have broken zero Schrader valves. I have broken 3 Presta valves. One when the pump slipped, and two for absolutely no reason at all. The valve core is exposed, and the stem is thinner. They are just delicate, and that's the way it is.

OTOH, I have had the pump slip several times resulting in significant torques on the valve stem with Schrader valves, and nothing has happened.

Use of a typical hand pump with a typical valve and typical possible forces such as if the pump slips or is not pulled off 100% axially with the valve should not have a significant chance of catastrophic failure, period.

Thus, Presta is unsuitable / unreliable and all my rims immediately get drilled for Schrader. Use a 21/64" drill bit, deburr the hole afterwards, make sure you get all the metal shavings out of the rim afterwards. Done.

BTW, I use Schwalbe Schrader tubes that look like this:

https://encrypted-tbn0.google.com/images?q=tbn:ANd9GcQFch_g799MNcKMOuFq6Iin9Gh_WeshbvyuQzoInnZNHYh_eJYv-w

Three broken stems over several decades... there are lots of things I wish were so "unreliable." :lol:

Three broken stems over several decades... there are lots of things I wish were so "unreliable." :lol:

Actually, all of those were over a period of 4 years or so when I got into "good" bikes and thought that Prestas were what "serious" riders used, and before I found out they sucked. It actually works out to about 10% of my flats with Prestas were because of broken stems/cores.

Great info from everyone!

I had started a thread on nitrogen when I first enrolled here at BF since I had read on it's properties when used in cars, but it would only be practical if it was easily available, and there's only 1 gas station in my area which has it (again only with Schraeder valves!).

As for bicycle tire pumps... well I've amassed a small collection of what I could find here in Athens, with my primary pump being a Crivit floor pump purchased at from a super market which has held up remarkably well compared to much more expensive pumps. I also carry a Beto portable double-action pump with built in guage which isn't very practical since it need excessive force in order to top up 5-10 psi @ 72psi which the tires are rated at.

@when, the Schraeder valve used by Schwalbe seems very compact compared to other brands and will probably need the least amount of filing to fit on my rims. I'll check the dimensions FB mentioned during the weekend and if possible will see if I can get my hands on a Schwalbe tube to test it out.

Without wanting to be a troll, I have one last question on this topic...
A few years back, here in Greece, I had purchased a small metal aerosol canister named "FAST" which was basically a car/motorcycle tire inflator with a foamy sealant which plugged the hole and was used after you got a flat tire. I used this product once on my old Honda motorcycle and it worked exceptionally well. Does such a thing exist for bicycle tubes (I'm well aware of Joe's no-flat, slime and the new Michelin Protek Max tubes, which already have the fluid in them)?


Edit: Googled it and found this: http://www.cyclocrossworld.com/hutchinson-fast-air-tire-sealant , looks interesting!

....and before I found out they sucked.


Of course you're entitled to your opinion, and free to express it. I'm not going to waste time selling you on Presta valves because like Rhett Butler, I don't give a .....

OTOH, because you have a problem with something that millions of people are having good success with, barely warrants a generalization like this.

Great info from everyone!

I had started a thread on nitrogen when I first enrolled here at BF since I had read on it's properties when used in cars, but it would only be practical if it was easily available, and there's only 1 gas station in my area which has it (again only with Schraeder valves!).

As for bicycle tire pumps... well I've amassed a small collection of what I could find here in Athens, with my primary pump being a Crivit floor pump purchased at from a super market which has held up remarkably well compared to much more expensive pumps. I also carry a Beto portable double-action pump with built in guage which isn't very practical since it need excessive force in order to top up 5-10 psi @ 72psi which the tires are rated at.

@when, the Schraeder valve used by Schwalbe seems very compact compared to other brands and will probably need the least amount of filing to fit on my rims. I'll check the dimensions FB mentioned during the weekend and if possible will see if I can get my hands on a Schwalbe tube to test it out.

Without wanting to be a troll, I have one last question on this topic...
A few years back, here in Greece, I had purchased a small metal aerosol canister named "FAST" which was basically a car/motorcycle tire inflator with a foamy sealant which plugged the hole and was used after you got a flat tire. I used this product once on my old Honda motorcycle and it worked exceptionally well. Does such a thing exist for bicycle tubes (I'm well aware of Joe's no-flat, slime and the new Michelin Protek Max tubes, which already have the fluid in them)?


Edit: Googled it and found this: http://www.cyclocrossworld.com/hutchinson-fast-air-tire-sealant , looks interesting!

Zefal makes a sealant in liquid and a foam in arasol that inflates the tire to 30PSI at the same time.

PS Whaterever anyone told you about nitrogen doesn't apply to passenger cars and even less to bicycles.

I actually have a couple of these adapters, but they never really seems to work correctly, especially at gas stations which have the portable pumps (thankfully the air's still free here in Greece!)....


PV adapters vary in length and whether they have O-rings or not. If you have O-ring adapters, they'll make a good seal on the valve, so it's a matter of the length. Use a medium file to make the top slightly (1mm or so) above the top of the PV stem, This will make them a better match to the SV dimensions pumps and gauges are designed around.

Also note, some adapter's ID at the top is slightly larger than a Schrader (correct spelling in USA) valve and may not work well with gas station chucks, though they're fine for gauges.

In the other direction, I want to start using Presta valves on rims with the larger Schrader holes. I was about to put a small rubber washer on the narrower valve stem, install and see what happened. Has anyone tried it?

You may find an appropriate rubber grommet in a hardware store..

apparently, not distributed in US, but ..
Mavic makes a schrader hole to presta stem adapter.
a split plastic piece that has a little lip in it to hold it in place on the rim.
expect SJS in UK will ship them.. they show them on their site.

A few years back, here in Greece, I had purchased a small metal aerosol canister named "FAST" which was basically a car/motorcycle tire inflator with a foamy sealant which plugged the hole and was used after you got a flat tire. I used this product once on my old Honda motorcycle and it worked exceptionally well....
. ?
!

Sealants do a decent job plugging or preventing small leaks, but to my knowledge won't solve your slow air loss problem, which is due to the molecular porosity of inner tubes.

Bicycle tubes loose air for the simple reason that they have fairly large surface area compared to volume. In addition they also are inflated to higher pressures. About the only ways to improve this are to use thicker (usually cheaper anyway) tubes, or switch to wider tires run at lower pressure.

I run 1.9" tires at 3.6atm on my commuter and only need to top off about every 3 weeks, vs my sport bike which needs topping off every day or two.

Use a flat head screwdriver. Take it slow you don't want cracks in the rim. When the size is correct sand the hole by rolling a piece of sand paper into a tube.

In the other direction, I want to start using Presta valves on rims with the larger Schrader holes. I was about to put a small rubber washer on the narrower valve stem, install and see what happened. Has anyone tried it?

Schwalbe Presta tubes come with a valve stem retaining ring that has been intentionally designed with a relief that will let it sit in the larger opening of a schrader valve stem opening. Addittionally, Schrader tubes are a higher quality and have been engineered to be more elastic, lose air slower and weigh less than most common tubes.

I heard somewhere that back in the day, you would lose a few pounds pressure when removing a bicycle pump nozzle from a schraeder stem. This didn't happen with presta valves, and that was the main reason for their existance. The new bike pump nozzles don't have this leak problem, so now there really isn't a need for presta valves.

I heard somewhere that back in the day, you would lose a few pounds pressure when removing a bicycle pump nozzle from a schraeder stem. This didn't happen with presta valves, and that was the main reason for their existance. The new bike pump nozzles don't have this leak problem, so now there really isn't a need for presta valves.

The same could be said of Schrader valves.

Let's see, PVs are lighter, narrower for improved bead clearance on narrow rims, simpler to pump, no depressor needed, amenable to extending for deep V rims, and probably have other virtues. So while you and many others may not need them, others might, and others yet may simply prefer them.

If there were a federal mandate saying we could only have one or the other, I'd vote for Presta. but fortunately we have a choice, and are free to use whichever we prefer.

Please don't take offense, but I think the problem is that no one ever showed you the care and feeding of Presta Valves. if you were to poll this forum, or any group of experienced cyclists they'd tell you that they prefer PV for a number of reasons.

Yes, it's easy to break the outer stem off. But it's just as easy not to, and doesn't matter either way. The "flexible" body you're seeing on some SVs is a design defect where in the brass (or steel) body of the valve is too short and ends in the rubber base cone outside of the rim. Countless cyclists have been stranded when these snap off while pumping on the road.

Obviously it's your bike and strictly your decision which valves you prefer.

Incorrect.

Except for this part: "Yes, it's easy to break the outer stem off." But the follow-up statement is totally, totally false.

Bottom line: I don't have to think about Schrader valves. They work, they are reliable, I've NEVER had one fail Prestas are temperamental and delicate. Why bother?

Incorrect.

Except for this part: "Yes, it's easy to break the outer stem off." But the follow-up statement is totally, totally false.

Bottom line: I don't have to think about Schrader valves. They work, they are reliable, I've NEVER had one fail Prestas are temperamental and delicate. Why bother?

I don't think you got my post. There's no need to debate the merits of either valve and somehow crown a winner. Both are readilly available and anybody is (still) free to use whichever they prefer. Some people don't like PVs, and that's no problem, likewise others do like PVs and shouldn't have to justify themselves to anybody.

As to whether either is junk, or great, we might as well debate whether steak is better than lobster.

Thanks! I'll look into the dimensions tomorrow morning FB.
As for Presta vs. Schraeder (finally spelled it correctly!), it's more a matter of convenience since I'm surrounded by gas stations near my home and work which of course only have Schrader valves on their pumps. Although what @when said does trouble me a bit since I broke the stem of a Presta valve a few weeks ago, although it was a stupid mistake on my part.
I am surprised you didn't blow your tire at the gas station. The volume of air that comes out of those compressors is to much for a bike. I have been riding a long time and been mechanicing bikes for years. Do yourself a favor and get yourself a floor pump with a gauge on it and stay with the Presta valve. They don't have as many valve problems as the schraders. you can get an adapter for a buck or two at bike shops that goes over the presta that will allow you to use gas station air if you want. thats my 2 cents

Schrader valves are for girls bikes and trikes in retirement communities.

Schrader valves are for girls bikes and trikes in retirement communities.

LOL You stand a good chance of annoying a number of professional female bike racers with that comment!

I am surprised you didn't blow your tire at the gas station. The volume of air that comes out of those compressors is to much for a bike.

100's of stops at service stations over decades.. have never experienced any problems with air pressure blowing tires. But I don't hold the fill nozzle on the tire admiring the landscape either. Any air compressor anywhere will blow any tire.. if the high limit pressure is well above the burst limit of any flavor of tire being filled.

Blowing a tire from a portable air tank (90% of gas stations in Greece use these) is highly unlikely since they're made for around 90-100psi max, even though the guage goes all the way up to 160psi. Most of the time, I have to refill the unit to max capacity just to have it reach 72psi which I use.

http://www.olkem.gr/images/products/1239103984-c-varelaki_blitz.bmp

I heard somewhere that back in the day, you would lose a few pounds pressure when removing a bicycle pump nozzle from a schraeder stem. This didn't happen with presta valves, and that was the main reason for their existance. The new bike pump nozzles don't have this leak problem, so now there really isn't a need for presta valves.

The problem still exists with any kind of chuck. To fill a Schrader valve, you have to depress the valve to open it...usually with some kind of pin in the pump chuck. If you don't have air in the pump hose, like when using a hand pump, the air in the tube will rush out to fill the hose from the chuck to the check valve. If your pump hasn't got a check valve or if the check valve is defective, the air in the tube will fill that volume too. Thus, just by pumping up the tires, you are losing air from them. If you don't have a good seal on the chuck and you hear leaking air, you are losing pressure from inside the tire too.

A presta valve, on the other hand, seals with the pressure from the inside of the tube. If you depress the valve stem, you release air. To open the valve, you use the pressure in the hose of the pump. When the valve opens, the pressure in the pump and hose is slightly higher than the pressure in the tube. The valve opens, allows the pressure to equalize and the closes if the pressure in the pump hose drops. If you fail to seal the chuck properly, any air escaping from the hose is just the pressure in the hose. The presta valve will close and keep the air in the tube. The 'WOOSH' you hear when you release a pump hose from a presta valve is just the air in the hose escaping. The same can't be said for the Schrader valve. You can still have the pin engaging the valve which will let air leak from the tube.

As for the supposed delicacy of a presta valve and the ruggedness of a Schrader, I managed to destroy a number of Schrader valves as a kid from riding the bike with too little air in them. If the tire starts to creep, the Schrader valve stem is very susceptible to cuts on the rim. Most people aren't going to run across too many of the stems like when shows above. I've been working on, riding and around bicycle for 30+ years and I've only seen 1 or 2 of that type. The rubber coated variety is much more common and much easier to damage.

The perfect solution would be a good quality presta/schrader adapter. I'll try and make the modifications FB suggested on the adapters I have, unless someone here knows where I can purchase the good quality ones (the ones I have are brass, do have o-rings but never really fit the presta valves).

Three broken stems over several decades... there are lots of things I wish were so "unreliable." :lol:

+1

I've torn a couple of Prestas off, due to a folding tire that was amazingly prone to slipping. Maybe a schraeder would have done better. Maybe not.
Apart from that I've had one Presta suffer some kind of contamination issue and refuse to seal, and one removable core Presta where the core decided to bond permanently with the cap(quite a nuisance at the time).
Given the time span, not really a significant issue. For ease of inflation, I'll stay with presta.

100's of stops at service stations over decades.. have never experienced any problems with air pressure blowing tires. But I don't hold the fill nozzle on the tire admiring the landscape either. Any air compressor anywhere will blow any tire.. if the high limit pressure is well above the burst limit of any flavor of tire being filled.
my tire blew once in a service station and about 6 times on my personal compressor even when the pressure was below the recommended amount. It throws a lot of air quickly into a small area and if the tube is not strong can blow the tube.

work on your technique instead

In the other direction, I want to start using Presta valves on rims with the larger Schrader holes. I was about to put a small rubber washer on the narrower valve stem, install and see what happened. Has anyone tried it?

http://www.biketiresdirect.com/product/wheel-mfg-presta-stem-savers

In post #11, FBinNY suggests leaving the PV to SV adapter on permanently, an option I am considering. I assume this means leaving the knurled knob on the top of the PV unscrewed. Will a PV leak if the knob is left in the unscrewed position while the adapter is mounted?

my tire blew once in a service station and about 6 times on my personal compressor even when the pressure was below the recommended amount. It throws a lot of air quickly into a small area and if the tube is not strong can blow the tube.

Then your tubes are of very low quality.. or old... or both.

I'm pretty sure I have some of those in my workshop. PM me an address and, if I can find them, I'll mail a pair to you.

They're not the easiest thing to fit onto your rim. When I use presta valve tubes in a rim that's drilled for schrader I usually just thread the presta nut all the way down on the stem and just let them stick out through the bigger hole.

I've had many problems with both styles of valves over the years.....each has it's advantages and disadvantages. Pick one and stick with it.

I got some new rims for a wheelset I'm going to build and they came drilled for schraeder, but with the plastic eyelet thingies to allow you to put prestas in there (26" rims). I've been going back and forth about which type of tubes to go with. Probably will go with the schraeders because I have a couple of spares on hand and they're easier to find, but will probably keep the eyelets in case I change my mind (or for when I run out of spares).