Blightybiker

Hello all,
I hope you are all keeping well in this newly changed World.

Here is a short story of a small cycling misadventure:

Yesterday I thought I would go out for a spin on my Raleigh Grand Prix. As ever, I pumped up the tubes, to get the best out of the ride. On the rear tube, as I approached what I would consider the right pressure I heard the dreaded hissing of escaping air. I faffed around for a bit, cursing throughout, before removing the rear wheel and tyre. The tube, a Sunlite 700 x 20-25, 27 x1", did not owe me anything: I have been using it and its front wheel twin, for about 8 years. The air was escaping from a small tear at the base of the valve stem, where it's glued to the tube itself. I think the small waggling around of the valve stem that happens when I use my Zefal pump had fatigued that point in the tube. The valve is a Schraeder and there is no lock nut on the valve stem. (On the Michelin tubes I used many decades ago there was a lock nut. This makes the stem position more stable.)

My wheels are 27" and have chromium-plated Sturmey Archer rims. The tyre is a 27" x 1/4" Kenda. So it seems that the failed tube was the wrong size anyway.
I have just ordered a pair Of Continental tubes, of the correct size this time. Because I wanted, for an obvious reason, to have a locknut on the valve stem I was compelled to order a tube with a Presta valve: the tubes with Schraeder valves did not have a lock nut. I also ordered a couple of Presta-to-Schraeder adapters, to give me more flexibility when needing to inflate my tyres.

Have a I made a sensible purchase? I see on the Sheldon Brown website that Presta valves are not as robust as Schraeders but they are easier to inflate.
Sheldon Brown

dddd

Consider that the seeming "stabilization" of the valve stem from the locknut can only occur to the extent that the nut exerts a push/pull on the rim/stem respectively.
So the nut is just applying tension on the valve stem, resisted only by the rubber attached at it's base.
Do we really want this to occur, or is it better to stabilize the pump head against an immovable object while pumping?

I've used the rear corner of a bike's saddle as a pump head rest, which worked well. The bike was of course laying on it's side.
And I've used a protruding corner of a curb to rest the pumphead on. A rock or stump is also good.

Another approach is to pump with the valve stem pointing down, so that the detached wheel is not constrained so as to exert resisting force to the motion being fed into the valve stem by the pump. So only the inertia of the rim and tire exerts any lateral force at all.

Best of all might be to use a hose or a C02 cartridge, though I carry neither.

Shraeder valve stems are really tough, so why not stick with them and use a pump that is compatible?

And beware how a rim adapter might exert resisting force against air pressure at the base of the valve, possibly trying to peel the tube from the stem. A steel rim isn't going to be able to support the valve stem because it has no depth to it where the hole is, and it can't even support an adapter against much in the way of tilting unless it's a tight fit.

Lastly, a Presta valve in a Shraeder-sized hole may expose the tube and cause dry-rot over time, especially where smoggy air exists.
You can shield the tube there while also protecting it from the hole's edge by fitting a square of cloth rim tape over the valve stem and to the inside of the rim. I poke a small hole in the tape to give a tight fit against the threaded stem. This has been reliable for me on many steel 27" rims, and I do not use a nut.

I use both Presta and Shraeder valve stems with old 27" rims drilled for Shraeder. When I use a presta valve in a Shraeder hole it is only to be able to use lighter-weight Presta tubes. My carry-along spare tube has to be Presta though so that my Presta-only mini-pump can reinflate the tire on the road following a tube swap-out.

Blightybiker

Many thanks for your advice, dddd.

First, my new Presta-equipped tubes have shipped now so the die is cast .

I would happily use a hose if I could find one was compatible with my Zefal pump but I am not sure if that is possible. I'll do some more research on that.
I think your suggestion of reinforcing the arrangement with a square of tape is promising and I think that is what I will pin my hopes on.

Thanks again!

Miele Man

If I use a Presta valve tube in a rim drilled for a Schrader valve I also use a thin washer I've filed the sides of to fit into the wheel well of that wheel. The washer has a hole just large enough to fit the Presta valve through. Oh, that washer goes under the rim tape.

Cheers

dddd

It does appear that if the stem fits tightly enough in the hole in the washer that it won't be the rubber supporting any tension from the nut, since the metal itself flares out slightly at the base of the threaded or non-threaded stem.

The way that rims support the Presta valve stem base and tube varies quite a bit when double-walled rims are added in, some of these have wildly-varying hole-size differences in the "inner" wall even as the visible "outer" wall is clearly sized for the Presta stem. The bigger hole allows the rubber reinforcement and the bigger end of the stem to settle in and thus better support the wall of the tube evenly right to the valve stem attachment. But only when both such holes are small will it prevent the stem from rocking too much while pumping.

I still know of no perfect solution, or what is really best, but Shraeder valves are generally trouble free and durable, with or without any threading. Thankfully, today's wider rim profiles allow more room for the reinforced rubber attached to the base of a Shraeder valve stem, even as perhaps fewer of them come drilled that way unless targeted to low-end applications. To that I say "three cheers for low-end rims",

Miele Man

To dddd.

I find that most Schrader valves I've used in the past few years have the rubber far enough up towards the end of the valve that it take a fair bit of pressure to get a pump head onto the valve far enough to inflate the tube. Then, to get the pump head off the valve requires quite a bit of twisting and pulling on the pump head. YMMV

I've never head any problem with Presta valve tubes and my washer adapter in a Schrader valve hole..

Cheers

dddd

I sometimes come across tight-fitting Shraeder pump heads. Some pump heads require force so I will put some spit on the threads for a while until the rubber grommet breaks in. I use a twisting action when removing the pump head which makes that part easy.

branko_76 

The same set? I've been thinking about getting a pair.

branko_76 

Maybe you hold the valve in position while twisting the pump head, but in general it's not a good idea to twist a valve.

branko_76 

I have several pairs of 27" rims with straight inner walls (no hook). Anyone still using these types of rims? If so, what tires are you using?

dddd

If you examine the manner that the chuck grips a Shraeder valve, it's apparent that twisting causes almost no torque on the valve stem, versus pulling it straight off which requires a lot of force if the pump head grips like some of them do (even after the lever lock is released). So for me and my particular pump, I twist every time.

I don't twist when it's a Presta valve, simply because it seems that with the much smaller gripping diameter that twisting seems to offer less of a beneficial effect on the release force. The Presta valve stems are the only ones that ever fail where they are bonded to the tube, so lubricating the threads with spit if it fits very tightly and most importantly not pressing the pump head onto the larger-diameter threads helps them not to fail.
I should mention in this regard that all Presta pump heads are designed to grip only on the smaller diameter cap threads, not on the larger nut threads. It's only when a pump head is worn out (usually from being forced onto the larger diameter threads) that it necessary to engage the larger-diameter threads of a Presta valve.

dddd

You always must use wired-on (versus folding) tires with hookless rims. There is usually no reduction of the tire's rated pressure when using such "straight-walled" rims, though some vintage rims (from Weinmann in particular) were known to have slightly too-small of a bead-seating diameter for the tire to be safely inflated to rated pressure. It was more of a quality-control thing in my opinion, since some pairs of rims had one that could take pressures and the other that could not.
Quality control problems more often arise with OEM rims, since QC corners are cut when the buyer negotiates for lowest prices.

Some rims are stamped "W/O" next to the manufacturer's markings, usually near the valve stem (it stands for "wired on").

Miele Man

Yes, I do hold the valve stem when I'm twisting the pump head in order to get the pump head off the Schrader valve stem. I know that twisting a valve stem is a great way to get the valve stem to fail where it attaches to the tube. LOL

Cheers

branko_76 

I see. Being stuck at home, I went thru my collection of tubes and several had hole near the valve stem, some schrader, some presta. They may have been caused by me pulling the pump head off after inserting too far. Not sure.

Regarding the diameter of the presta stem, I was not aware that the stem tapered. Will keep that in mind the next time I force a pump head on one.

FrankBooth

This thread is a fantastic resource, I had my Maruishi switched out from Steel to Alloy not too far back.

I picked up a set of Sunlite Gumwall as I'm trying to get more comfortable working on my own bike, though it seems the pricing for better quality 27" isn't too bad.

Classtime 

Yesterday, I bought a pair of Sunlite 27 x 1 1/4 from the LBS at 19.95 each. Fine. I like the shop and no one else had a pair of 27 x 1 1/4 tires. They felt very heavy and thick but what do I know? I am new to 27". I put them on my bike and rode around a bit. Yuck. They are tires. Today, I went to another shop for a chain and checked their tire rack. (When I called they only had one Pasela. That is why I bought the Sunlites from the other shop.) The Pasela is so much lighter and thinner and feels so much more like my nice 700c tires. In the future, I WILL NOT BUY SUNLITES AGAIN.
FrankBooth If you have the luxury of returning your tires and ordering Paselas, do it. So many BF members posting in C&V swear by them for a good reason.

FrankBooth

Appreciate the heads up, I was genuinely unaware of how close in price tires ran. Seems like Schwalbe and Panaracer are the goto's.

FrankBooth

Is there any significant difference in performance between the Pasela's and the Pasela's with Protite?

I want to order locally and the shop has only the Non PT Pasela's.

Classtime 

I think it depends on your definition of performance. Flat proof performance=PT. Light weight flexible sidewall=Not PT. (I admit that I have not ridden either but I have researched because of my new TREK 620 designed for 27". I handled a Non PT pasela at the local shop and was impressed how "flimsy" it was. Some folks think a flimsy tire can't perform.

mkeller234

I have both version of the Pasela. I honestly can’t say that I would notice a huge difference between them. I’ve always figured that the differences between my bikes were more significant than the tires. I usually trend towards the flat resistant tires because I often find glass along my ride.

Once upon a time I shelled out the money for high zoot challenge tires. I got so many flats that year that it didn’t feel worth it.

Either version of the pasela is a good tire. I’d say make the choice depending on what sort of roads and debris you will ride on.

I bought the Swift sand canyons based on feedback I read here. I like them a lot too, but again, I don’t know if I’m sensitive enough to the nuances of tires like others. I couldn’t say if I notice a difference compared to paselas.

FrankBooth

Thanks! I was thinking more along the lines of the the PT maybe having a bit of extra weight that would affect the rollability. As far as I can tell, that doesn't seem to be the case. I have a pair on the way.

Many thanks, I ended up going for the PT just because I'm in NYC and my wheels right now aren't quick release. So less potential need to have to take them off while riding, the better.

Paint Job Steve

Anyone have any experience with Specialized RoadSport tires? Gonna make a purchase soon I'm looking hard at these things, I just bike for fun/exercise and I'm looking to haul maximum ass. Riding Gatorskins now and it feels like I'm hauling minimum ass. Open to other suggestions for a fast tire in 27 x 1 1/4. I could be talked into trying some Paselas too.

Paint Job Steve

Bump on the above question. Specialized RoadSport good or no good? Think I might have picked a bad time to ask, I can't tell if the forum got a software update or it got hacked by North Korea. Either way this place looks like crap.

Paint Job Steve

Sorry for 3 posts in a row but I need the post count.

Paint Job Steve

Really sorry for 4 posts in a row this what I was looking at. Clicked on view full forum and back to normal.



Good news is can post links and pics now, again sorry to be a pain in the ass. This is the tire I'm interested in. Please let me know if you know something. No big whoop.
https://www.specialized.com/us/en/roadsport/p/155765