Wednesday, 1 June 2011

Choosing between inner tubes and pumps

Few people pay much attention to inner tubes. They're a bit boring. You can't see them as you ride. Actually, it is quite reasonable that most people pay little attention to them, as most of the time the differences between quality inner tubes are slight, and for most people they don't matter.

However, there is a difference in the construction, and some are better for some purposes than others. I've currently got three different inner tubes in stock which are suitable for relatively narrow 20" (ETRTO 406) tyres. This is how they differ:

The lightest of the bunch is the Schwalbe SV6A. These have a claimed weight on the packet of 65 g, and that's exactly what my kitchen scales say they weigh.

This inner tube is the lightest of the three, and also feels most supple. I have not tested rolling resistance with this inner tube, but if there's a difference you can expect this will be the best performer.

It will probably also lose pressure faster than the other options, so you'll need to pump up your tyres more often with this inner tube. Also, maybe it's less damage resistant too.

Reflecting its special status, the SV6A costs an extra €2.38 over the price of normal Schwalbe inner tubes.

The second lightest is also a Schwalbe - the SV6. It says nothing on the box about the weight, I found it to be 95 g.

This is a standard grade inner tube from a quality manufacturer. It's still actually quite a nice supple inner tube, and it's what I have in the front tyres of my Mango at the moment.

Either this or the Continental are a good choice for everyday use.

The heaviest of the three is the Continental Compact 20 inner tube. Continental make extra thin high performance inner tubes (akin to the SV6A) in other sizes, but not for 20" wheels.

This is again a standard inner tube from a quality manufacturer, which again means it is actually of good quality. According to my scales, it weighs 100 g, which is an irrelevant difference over the weight of the Schwalbe equivalent.

The construction of this inner tube is a bit different. The rubber feels thicker than the Schwalbe SV6, though given that they're about the same weight it obviously can't really be so different.

What is a little different is that the Continental is wider than the Schwalbes, even though it's only rates as being suitable for tyres up to 32 mm wide, while the Schwalbes are for tyres up to 40 mm wide. This makes it a little more difficult to fit into a narrow tyre. Continental also specify that their inner tube will also fit 451 size wheels, while Schwalbe suggest theirs will not.

Either this or the Schwalbe SV6 are a good choice for everyday use.

In practice, I find the Continental is a slightly awkward fit even within Continental's own 28mm wide tyres. It's just a bit too wide, and makes it more difficult to fit the tyres. As a result, I'm using the Schwalbe SV6 in those tyres at the moment. If I were racing, I'd use the SV6A as it is slightly lighter, and more importantly it is reckoned that due to its flexibility it will roll a little better. I'm using a Continental inner tube in my rear tyre, which is a bit wider than they recommend, but here it seems a good fit. I also carry a Continental as one of my spares spare (I have two for personal use).

I also weighed a few no-name inner tubes for the same wheel size. Most weighed about 130 g, but one was 200 g - a surprising difference. There is almost certainly a difference in performance between such an inner tube and those from the better manufacturers.

Valve types
Presta / French / HP valve
Another difference between tubes on offer is the type of valve in use. Some people have very strong feelings one way or another. It can be nearly a religious issue. However, I think each has its place

For racing, when you might actually care whether the pressure in your tyres is up to the maximum and want to measure them, there is a slight advantage of the Presta ("French") valve over the Schrader (car type) or Dunlop (also known as Dutch or English) valves. Also, as everyone else will be using these, if you borrow a pump it will already be set up to fit these valves.

Dunlop / Woods / Dutch valve
However, unless there is a special reason to choose, all three types keep the air in equally well, so most of the time it's best to use what's convenient and what you're used to.

In the Netherlands, there are sometimes publicly accessible pumps designed to accommodate the Dunlop valve, and you can buy very well priced floor-standing pumps which make pumping these up very easy indeed.

Schrader / Car valve
I use Presta valves for sportier bikes and Dunlop valves for our town bikes.

As much as possible, I avoid the Schrader type as they're most difficult to push the pump on and off, and due to the larger area of pressure they're the type which most often gives problems with keeping the pump head on the valve while pumping.

However, I might feel differently if this was the most commonly used valve type where I lived as the convenience would then be on the side of the Schrader. In the US, these seem to be the most popular valves in use.

Pumps
Some of you might have noticed that for a long time now we've had a bike parts and accessories shop which didn't sell any bicycle pumps. I've now added two floor-standing pumps to the shop website, including one which is light enough to take along with you, if a little bulky. However we still don't have a truly portable small pump.

They seem an obvious thing to have, so why not ? The problem is finding a product which we can trust ourselves. We said from the beginning that we'd only list things that we either already use ourselves, or that we'd happily use ourselves. This is what we're sticking to.

One pump which we don't recommend and won't be selling is the SKS Airboy.
SKS Airboy. Don't buy this, even for just £1.
I bought my "Airboy" at the Mildenhall Rally, probably ten years ago. It cost me the grand sum of one pound. At the time I thought this was a bargain. However, it's too flawed to be useful. It has a double headed design with one side for Presta or Dunlop valves and the other side for Schrader. The pump relies on air pressure to keep a small rubber ball in a position to block the pump head that you're not using.

There are a number of problems with this idea. Usually, this means you can only pump upwards as initially gravity has to put the rubber ball in place. That may not sound like a big issue, but it becomes one as soon as you try pumping up tyres on a bike with laden panniers or a coat guard. However, the problems go beyond this issue. The heads don't fit well on valve stems for any of the three types of valve, and it's impossible to pump tyres up to an adequate pressure without the pump popping off the stem.

This problem hit me a few weeks ago when I got a puncture on a ride. Before leaving I'd picked up a pump to take with me, but not until I got the puncture did I discover it was this pump. At first I thought it would be OK, as in the past, I'd managed to get just enough air into a tyre with this to at least ride to a bike shop, but not this time. I had to walk a distance and ended up buying a working pump at a bike shop.

Anyway, I bought it ten years ago, so why am I writing about it now ? You can still buy these ! I've seen the exact same model for sale this year. To double the insult, in the last few days I accidentally bought another pump with exactly the same problems. We need something sensible and usable in the shop, so I added what seemed to be a well speced, but also well priced pump to an order from one of our suppliers. When it arrived, it turned out to be an SKS under a different name, with a variation on the same kind of head. It has exactly the same issues as the older one, plus a new problem: A spring works against you for almost half the stroke, making it difficult to achieve much pressure even if the pump would stay on the valve.

SKS used to be a very good name for pumps. I've a few old ones which work very well, and I'm sure they also still produce good models. However, I'm currently waiting for a different manufacturer's pump to turn up from a supplier. It's not fancy and expensive, because portable pumps tend to get damaged or lost. But if it works well it will appear on the shop website in a few days.

14 comments:

dr2chase said...

There's a pretty good screw-on adapter for Presta, that makes it effectively a Shrader, if you need that. I use Presta, partly because with the large lower pressure tires that I use, the valve stem needs a retaining nut (like Presta valves have). Otherwise, there is a range of pressures, between about 15 and 30psi, where a Shrader valve sinks into the tube and cannot be engaged (pressure is too low) but I lack the hand strength to press the valve in from the back(pressure is too high).

Note that Schwalbe supplies at least some Shrader-valved tubes that include the retaining nut.

One thing I have seen in the US, is a substance called "Slime" squirted into the tubes to provide some amount of puncture protection. Whether you would want to use this or not depends on how you feel about patch versus replace; I bought a used bike that came with Slimed tubes, and all was well, until it finally developed an unstoppable puncture. When I removed the tube to patch it, inflation outside the confines of the tire enlarged all the previously plugged smaller holes (perhaps a dozen!), and they all leaked slime, making it impossible to find the culprit and also contaminating the surface I might want to vulcanize.

Since I'm a patch-and-patch-and-patch sort of guy, Slime is not for me, but someone who simply wants to go as long as possible between replacing tubes, might be well-served by it. It has weight, but being liquid-ish, is quite flexible.

However, if you have, say, a wheelbarrow tire that won't hold air, that you have no intention of patching anyway (do they even have tubes? I do not know), Slime could be just what you want. It certainly worked for that purpose.

I've tried several portable pumps. I tore a Quicker Pro in half; it didn't work so well after that. I'm currently using a Lezyne, and had to use it to inflate a 2.35x26" tire by the side of the road, and I don't hate it (yet).

Paul Martin said...

I really enjoy these technical posts of yours, David! Thanks!

David Hembrow said...

Dr2chase: The adaptors are going to appear in the webshop as soon as I can work out which is which (descriptions which read "converts Presta to Schrader" aren't helpful when you can't tell which way they convert). Perhaps I'll just buy one of each. They're cheap.

You're right that Schwalbe's Schrader tubes include retaining nuts (I also don't know if this is all, or some).

Slime is, I'm afraid, another of those things which I don't recommend. I used it years ago and all seemed to be going well until on a long tour I went down some steep hills and warmed the wheels up. Then I also had unstoppable punctures as you describe.

Over the years, I've tried all the anti-puncture gimmicks, including Slime, solid tyres etc. None of them impressed with long term use. These days, if above all else you want to avoid punctures, I recommend one thing: Schwalbe Marathon Plus tyres.

Rob said...

I prefer the Schrader valves, since you can inflate those at petrol stations without converters.
I'm using this footpump with manometer, CAE-VPMSB-01 from Michelin. This one has been very reliable so far, and requires far less effort to inflate a tire to higher pressures (like required for Marathon Plus).

Anonymous said...

Regarding the Airboy popping off: how do you hold the pump ? I would be holding the pump head in one hand, thumb over the tyre and fingers under the pump so that a) there is no stress against the valve as I pump, and b) your fingers hooked under the pump would prevent it popping off due to air pressure.

Anonymous said...

I'm not a fan of Continental tubes, although my only experience with them is the free set that came with my Conti gatorskin tyres. For some reason the tube was just too big to fit properly around the wheel, I guess there was about a couple of inches too much material - the circumference was too large. Strange because the tyre and Specialized tube fit perfectly.

Micheal Blue said...

My foldable bike, Dahon, came with a pump built into the seat post. It was a great idea to do it that way. However, I found using it frustrating. It pumped very well, but screwing on the pump's hose would allow plenty of air to escape, so I had to pump the tube to a higher pressure than I wanted it to have. Then I bought a floor-standing Lezyne pump. Expensive, but looking nice..and working great...oh, what a difference! That's not even in the same universe. Anyway, my point is that a good quality, albeit expensive, pump is worth the money.
Otherwise I carry a small Topeak pump that has a lever that has to be flipped up to somehow lock the pump onto the valve. It seems to work OK, but pumping up a tube is more work than the whole biking trip.

David Hembrow said...

Anonymous: I hold it just as you describe. The problem is that there is very little space within the pump for the tube, no lever as described by Michael, to secure the pump head on the valve, and the rubber isn't enough to make an airtight seal. The result is that air leaks around the sides, the head tries very hard indeed to pop off, and, well, it's just useless. Old fashioned pumps with a piece of hose had a lot going for them, in that this resolves all these issues.

As you noticed, I'm using Schwalbe tubes in my Conti front tyres, but a conti tube in my Schwalbe rear tyre. Sometimes things just work out better that way. I do very much like the way in which Conti tyres are easy to mount and stay round on the rim with the minimum of hassle.

Michael: The problem with expensive pumps, for me, is that I lose them, drop them when cycling, run over them etc. For that reason, I prefer not to spend too much. It's possible to buy inexpensive pumps which produce high enough pressures - I'm going to find one and stock it. At home I use a bigger floorstanding pump than I'd ever carry on the bike. This moves lots of air, so achieves high pressures with ease.

The hose idea is good in itself because it relieves the problem of potentially breaking off the valve. However, sometimes these simply aren't well made, and of course it has to be the right hose. These are usually different for Presta vs, Dunlop valves, even though they look much the same. Try using a Dunlop adaptor with Presta valves and all the air comes out.

Green Idea Factory said...

@Rob: If you stop going to petrol (gas) stations for air, they will go out of business.

I bought a Silca floor pump with a Presta fitting 14 years ago. It got banged and the gauge broke and it could never stand on its own, but otherwise it's perfecto.

I have my own game of sorts, albeit with no physical prize: What is the problem with the second paragraph in my comment?

Willeke said...

I have a folder bike with schrader type tubes and a recumbent trike on which I prefer dunlop tubes but it came with schrader tubes.
I carry two adapters, one each way round, as at a time I used shrader as well as dunlop/woods tubes, replacing those d**** schrader tubes whenever I needed a new tube. But then I ran into the traveling pumps not strong enough and the people helping me only able to fill schrader type tubes.

For the folder I already had several adapters.
One of my adapters for Schrader tubes works good, the other two leak air when on some tubes but not on others.
The adapter to fill the dunlop tubes with a schrader head just works. It came with a bit of tube to schrew into some kinds of portable pumps, which I never used.

@GIF, your gauge could never stand on its own. Your pump could.

Micheal Blue said...

Dave, what happened to frame pumps? They used to attach to the bicycle frame so neatly, and they can also enhance the look of a bike. Do they still exist on the classic Dutch bikes?

Anonymous said...

I'm very happy with my BBB traveller mini pump. Small enough to take with you but all the comfort of a footpump.

Rob said...

My Schwalbe 622 inner tube with Schrader valve has a retaining nut, so it won't sink into the tyre when deflated.

My pump also has a lever on the connector to lock it on the valve, it won't pop off. With the Schrader valve you can also see the actual tire pressure, since it's pressed open by the pump nozzle.
http://www.youtube.com/watch?v=KiKg4k7sJPY

I haven't found a portable pump that works well, but since i'm using anti-leak tires (Dutch Perfect and Marathon Plus) I don't really miss one. In case of emergency there are plenty of petrol stations around.

workbike said...

Here there seems to be a consensus amongst most cyclists that Dunlop is the way to go. They are unfortunately my least favourite as from experience in the shop they are more difficult to deflate, remove, fit and inflate of the three designs. Car-type valves are very rare, which is ironic as we're such a car culture.