Problems pumping up tyres!

I hope you're not insinuating any kind of sexism on my part Digger?
I have a long history of being a patronising arse to both sexes thankyou very much. :P

I'm happy to believe that, like myself, you'd patronise anyone Hippy...

At 63kg I rode 23mm tyres at 95psi front and 100psi rear; 5-10 psi less in very slippery conditions; equal pressures for hillclimbs; maybe 100f/105r for TTing & RRing on reasonable roads. Clinchers, BTW.

At 70kg, I've generally gone to 98psi front and 103psi rear, or thereabouts, for general riding; and 110psi front and rear for Herne Hill.

At 63kg you were a fatty. Now you're 70kg I just can't keep idolising you any more.

I'm back down to 68kg. I hope that's good enough for an adorable body fascist like yourself.

The weight fluctuations seem to have no bearing on my performance* anyway.

*don't really ride a bike at the moment, so you can decide what I'm alluding to. Knock yourself out.

Aaaaaaaand, what's patronising about people citing a common pumping user error - the presta locknut oversight. Most of us have been asked the same question at some point in our bike maintenance history when our tubes have remained staunchly flaccid.

Aaaaaaaand, what's patronising about people citing a common pumping user error - the presta locknut oversight. Most of us have been asked the same question at some point in our bike maintenance history when our tubes have remained staunchly flaccid.

Must. Not. Make. Peurile. Comment...

As Two Omegas said a track pump with a skinny barrel like the Rennkompressor will be much easier to use for those who are lighter in weight.

You are tring to compress a column of air from 15 PSI to >100 PSI and the larger the volume of the column, the more force would be required. Two pumps 60 cm tall but one 2cm barrel and other 4cm would need double the force to get the same pressure in each.
Would need half as many pump strokes with larger pump but each requiring a larger force
per stroke.

I have Crank Bros hand pump that has two chambers inside which you can select; large volume (hard to pump) to get started then a small volume (high pressure) that is easier to pump but compresses a smaller amount of air to a higher pressure per stroke.

^^It was a bit of an RSVP post. But you've shown real character in ignoring the invite.

As 2 omegas said a track pump with a skinny barrel like the Rennkompressor will be much easier to use for those who are lighter in weight.

You are tring to compress a column of air from 15 PSI to >100 PSI and the larger the volume of the column, the more force would be required. Two pumps 60 cm tall but one 2cm barrel and other 4cm would need double the force to get the same pressure in each.
Would need half as many pump strokes with larger pump but each requiring a larger force
per stroke.

I have Crank Bros hand pump that has two chambers inside which you can select; large volume (hard to pump) to get started then a small volume (high pressure) that is easier to pump but compresses a smaller amount of air to a higher pressure per stroke.

Thanks for the physics lesson Steve, we have a Rennkompressor, doesn't work for the slighter in build...
see previous posts.

^ Didn't read that post as meaning you'd tried it yet :(

So skinniest barrel/lowest volume possible whilst still allowing mechanical advantage of getting body weight over the handle.

I use my knees to pump, if that helps. As in, back and arms straight, bend knees in a sort of froggy way. You feel like you look like a complete plonker, but it works for me... I am a weakling, and use a Rennkompressor.

Seeing Kate being physically lifted up into the air by the pump handle is what convinced me the problem is not technique and of course the Rennkompressor works for me but I'm a little heavier than her...

If we're doing physics, lets do it properly. Force = pressure x area. Double the diameter and you get four time the cross sectional area, so *four *times the force to reach the same pressure. Or more generally, the force needed is proportional to the square of the internal diameter.

I once built low-force 'track pump' from a specialized airtool road frame pump. It was intended for use by children launching water rockets, who struggled to reach the 50psig or so needed with conventional track pumps. It worked, but pumped tediously small amounts of air, so it was more fun to struggle on with proper track pumps. (I made a wooden T handle and base, and cannibalized the gauge and hose from a proper track pump. I don't still have it. If i was doing it again i'd use a slightly fatter pump and add a non-return valve at the pump end of the hose. (Maybe improvised from an inner-tube valve. Not having one would make it very inefficient at high pressures. That was less of an issue at 50psig.) Some of the longer frame-fit pumps look promising.)

List of smaller pumpers for experimentation?

1. Kate
   
2. LittleHeather
   

List of smaller pumpers for experimentation? (The Big Pump off, tomorrow, LMNH, 5pm onwards)

1. Kate
   
2. LittleHeather
   

I didn't realise this was on the sub-forum, (just click recent posts, me). Apologies to LH for being patronising. I didn't know this was a problem, I do now, I was wrong. Sorry for assuming it was user error.

No offense taken. It was mildly annoying to have the assumption made, but nothing that would make me cry like a girlie, trust me - I may not be up to pumping up my tyres (yet!), but I'm made of harder stuff than that emotionally ;) Thanks for the apology all the same - appreciated and duly noted.

List of smaller pumpers for experimentation? (The Big Pump off, tomorrow, LMNH, 5pm onwards)

1. Kate
   
2. LittleHeather
   dammit - can't make tomorrow - I'll be in Amsterdam for the weekend!
   

We could simply adjust Kate with a) bottles of water in her pockets and b) helium balloons, she could then represent about wide range of weights?

We could simply adjust Kate with a) bottles of water in her pockets and b) helium balloons, she could then represent about wide range of weights?

So, in order to move forward would the women of the forum like to post their weights in an open thread so we know how much to adjust Kate by?

8 and a half stone @ 4'11. Kate I'd join you but running up and down Streatham Common is the highlight of my Thursday evenings.........

Hang on a min!!! I don't see Kate volunteering to do this experiment. Kate?

May I recommend a pump that could be an answer to different problems mentioned here? It's the SPECIALIZED WINDPIPE.

*It's a portable pump that has a two-stage pumping mechanism. The handle itself has a two-part twist section, that goes into the main part of the barrel. If the thick part is used, I can pump my tyres easily to 40psi, with some proper effort to 60psi, and breaking out into a total sweat and huffing and puffing to 80psi.
At any stage of the pumping process, the second release can be switched/turned, and instantly the pumping becomes MUCH easier. In fact its easier to pump at 130psi (like my rear tyre is right now) than even 40psi on the Stage 1 release.

The end of the handle folds out to a T-shape, making it comfortable and easy to hold. The maximum rating of the pump is 230psi. This should be enough even for track racing tubs (tubular) tyres, and of course, much more than enough for any commuter or sporty clincher tyres. * *

The valve and adaptor attach securely, and NEVER let air escape when the job is done. Okay, just a gentle and quick pssst, that lasts a quarter of a second, so no realistic loss. * *

It's not as light or as tiny as the smallest portable pumps, but it buries all others in ability. I have a Rennkompressor at home, but the Windpipe goes everywhere with me. Of course what take seconds with a track pump, take minutes with the smaller pump. But due to its accuracy, lack of effort, size and ability, I feel its not only a track pump replacement, but also an essential bit of kit, for someone who might struggle with higher pressures.*

Older style end-of-line version - cheap!

1 Attachment

^Looks amazing, will obviously take a lot longer, my question is is this really easier to use than a track pump? It seems that it must be very efficient if it works on just muscle power rather than body weight...

Yes it is.

is this still going??

^can I draw your attn to post 97, Mr MG?

Fenella is approx 50kg and can happily get 120 psi into a 700 X 23c with our Renkompressor, I reckon that's pretty conclusive- unless there are many 40kg women on here?