What track pump

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thirdcrank
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Re: What track pump

Postby thirdcrank » 22 Dec 2017, 9:37am

I'm only guessing but I don't think that the stroke v bore of a pump makes a huge difference to the effort required, although it obviously affects the amount of air pumped per stroke. I wonder if a cheaper pump might not have a valve ie be made like an ordinary bike pump? With a valve, which is standard on any half-decent track pump, once the down stroke has built up the pressure, that's transferred to the hose and into the tube. Without the valve, a lot of the effort is wasted, especially if you are trying for higher pressures.

peterh11
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Re: What track pump

Postby peterh11 » 22 Dec 2017, 4:50pm

thirdcrank wrote:I'm only guessing but I don't think that the stroke v bore of a pump makes a huge difference to the effort required, although it obviously affects the amount of air pumped per stroke. I wonder if a cheaper pump might not have a valve ie be made like an ordinary bike pump? With a valve, which is standard on any half-decent track pump, once the down stroke has built up the pressure, that's transferred to the hose and into the tube. Without the valve, a lot of the effort is wasted, especially if you are trying for higher pressures.


The new pump does seem to build up the pressure much like the old so I don’t think that is the issue. It seems a perfectly decent pump and if I were bigger and stronger and the only one who needed to use it then it would not be an issue. I would expect that once you have 4 or 5 bar of pressure inside the tyre, the dominant factor will be the resistance to pushing more air in.

I also (now I have done a bit of research) notice that the pumps designed for high pressure (road usually) tyres tend to have a longer stroke and slimmer barrel, which would tend to reduce the force needed (same work through longer stroke: energy = force x distance) though it will mean you need more pumping to get to a given pressure.

Peter H

Brucey
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Re: What track pump

Postby Brucey » 22 Dec 2017, 5:07pm

pump barrels vary a lot in diameter/piston area and with it the effort required also varies. Pretty much any pump with a gauge will have a check valve in the base, but not all flow air as easily or have a small dead space in the base of the barrel, so pumping efficiency varies.

cheers
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thirdcrank
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Re: What track pump

Postby thirdcrank » 22 Dec 2017, 5:16pm

To clarify what I was trying to say: long thin = high pressure capability, fatter = more air per stroke, so more suitable for fatter tyres, which need more air but at relatively low pressure. I thought somebody has already made that general point above, which was why I didn't repeat it, but it may be on another track pump thread. I don't think I was dreaming.

Beyond that, I was looking for other reasons why your new pump was such hard work. If it's just a matter of difficulty reaching the pressure you want, the thinner the better.
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Brucey posted as I was typing.

Brucey
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Re: What track pump

Postby Brucey » 22 Dec 2017, 7:18pm

the other things that make pumps hard work include;

1) if you are pumping Schrader valves and the chuck isn't on far enough to open the valve

2) if you are pumping presta valves and the valve is not manually unstuck (opened once) before the chuck is attached

3) if the piston is not suitably lubricated, it gets pro-rata draggier as the pressure increases.

cheers
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RickH
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Re: What track pump

Postby RickH » 22 Dec 2017, 8:27pm

Brucey wrote:the other things that make pumps hard work include;

1) if you are pumping Schrader valves and the chuck isn't on far enough to open the valve

2) if you are pumping presta valves and the valve is not manually unstuck (opened once) before the chuck is attached

3) if the piston is not suitably lubricated, it gets pro-rata draggier as the pressure increases.

cheers

It might have been a bit (a lot?) of 3 going on but I found with my old, fat-barrelled track pump* (brand forgotten) that I would have to get my whole weight on the handle to get 25mm tyres up to 95psi. I've managed to push 170psi into an SKS Rideair with much less effort using its much slimmer Lezyne replacement.

(*it found a new life, at least temporarily, pumping fake blood for a low budget zombie movie that my youngest daughter was doing make up on! :shock: )

ratherbeintobago
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Re: What track pump

Postby ratherbeintobago » 17 Mar 2018, 8:30pm

Brucey wrote:You can fit pretty much any chuck onto any pump.


On which note, I have a Rennkompressor which is a thing of true loveliness apart from the brass push-fit Presta head. Has anyone fitted a Silca Hiro head, and is it (as I assume) just a case of pushing the Schrader fitting into the end of the hose, then screwing on the Hiro?

Brucey
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Re: What track pump

Postby Brucey » 17 Mar 2018, 8:49pm

with most types of hose you will need a clip of some kind to secure the fitting that pushes into the hose.

cheers
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ratherbeintobago
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Re: What track pump

Postby ratherbeintobago » 17 Mar 2018, 8:51pm

Brucey wrote:with most types of hose you will need a clip of some kind to secure the fitting that pushes into the hose.


That’d just be a case of reusing the jubilee clip that’s already on the hose, I’d have thought.

Are most hoses dimensionally similar?

Brucey
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Re: What track pump

Postby Brucey » 17 Mar 2018, 9:12pm

possibly. However if the hose is thin-walled, and the clip is even slightly the wrong size, it will leak, or relax its grip over time, and then leak.

Your average hose clip relies upon the thickness of the rubber to fit (the inside of the clip is not round) and the springiness of the rubber alone to provide any prevailing force on the connection.

There are many types of clip, many of which are a distinct improvement over a hose clip, e.g. (not all to the same scale)

Image

of which you might like to think about

fuel hose clip; thin and flexible, therefore rounder ('Y' series) or
spring type hose clip ('I' series);has enough prevailing force to remain secure, long-term.

BTW the I and Y series designations are not universal, and only apply to this supplier I think.

FWIW I keep a stash of spring type clips specifically for track pump connections. I slip the (slightly oversize) clip over the hose, then push the hose over the fitting, then wrap tape over the connection region to make it the correct diameter for the clip to work. Then I fit the clip, and then remove most of the 'ears' using a grinder. I then finish the job by wrapping more tape or using heat shrink over the top. If the ears are left in place they are a bit jaggy when handling the chuck (like a jubilee clip is). The remnants of the clip ears are usually enough to allow it to be removed if necessary, but the clips are so cheap they can be disposed of rather than re-used.

If fitted with enough prevailing force (by carefully adjusting the size using tape) the resulting connection is 100% reliable and so neat it won't ever snag on anything.

cheers
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mjr
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Re: What track pump

Postby mjr » 24 Apr 2018, 5:48pm

Just to return to this, two questions arose while I was looking for a new head for my pump (the washers in the current head appear to be stuck in there but they've lasted more than five years):

1. Are SKS and Park Tool Pro (1096R) the only lever-lock heads that are currently push-to-lock?

It seems crazy that with most lever-lock heads, you push the head onto the valve and then pull the lever up, risking pulling the head up and not forming a good seal and blowing the pump off and wearing the washers.

2. How do the push-on Presta heads from SKS and Silca work anyway? SKS part PP27, Silca part 225.SVC24.0
MJR, mostly pedalling 3-speed roadsters. KL+West Norfolk BUG incl social easy rides http://www.klwnbug.co.uk
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pwa
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Re: What track pump

Postby pwa » 24 Apr 2018, 6:08pm


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mjr
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Re: What track pump

Postby mjr » 24 Apr 2018, 6:10pm

pwa wrote:https://www.sjscycles.co.uk/pumps/topeak-twinhead-pump-head-hose-upgrade-kit/

I get on with these quite nicely.

Which is locked by pulling the lever away from the wheel, isn't it? If I wanted that design, I'd probably buy the £5 Decathlon version.
MJR, mostly pedalling 3-speed roadsters. KL+West Norfolk BUG incl social easy rides http://www.klwnbug.co.uk
All the above is CC-By-SA and no other implied copyright license to Cycle magazine.

pwa
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Re: What track pump

Postby pwa » 24 Apr 2018, 8:16pm

mjr wrote:
pwa wrote:https://www.sjscycles.co.uk/pumps/topeak-twinhead-pump-head-hose-upgrade-kit/

I get on with these quite nicely.

Which is locked by pulling the lever away from the wheel, isn't it? If I wanted that design, I'd probably buy the £5 Decathlon version.


Yes, pull. Very nicely made though. My ancient Topeak pump is now a bit like trigger's broom, 50% replaced. It's good that there are still things you can buy spares for. The current hose is longer than the original, which is really useful. Are the Decathlon ones good? The Topeak head is only £6.99 from SJS without the hose. But if you find that design awkward to use.....

pwa
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Re: What track pump

Postby pwa » 24 Apr 2018, 8:27pm

duplicate post
Last edited by pwa on 24 Apr 2018, 8:29pm, edited 1 time in total.