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Old 05-26-12, 11:55 AM   #1
kamtsa
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Floor pump for light people?

Hello mechanics,

We have a ToPeak JoeBlow Sport II floor pump and it serves us well (we use up to 90psi). However, when a child or a light person try to use it it requires too much force to get to 90psi.

Are there floor pumps with gauge that require lower force (that is smaller tube ID)? I could not find any reference to the pump force or tube ID of floor pumps, just max PSI, which is not the same.

Edit: I need a pump with a hose that accepts after market valves like this one http://www.amazon.com/Silca-Locking-.../dp/B0028MUV3Y

Thanks,
K.

Last edited by kamtsa; 05-26-12 at 12:06 PM.
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Old 05-26-12, 02:46 PM   #2
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Road Bike Action (June 2012) magazine reviews 8 floor pumps. One piece of data is "strokes to 100 psi", some as low as 13 to 30 strokes. Unfortunately neither piston diameter or stroke length is provided, so handle force at 100 psi cannot be determined.

Assuming stroke length is about the same, the one that requires 30 strokes probably has a small diameter piston (Icetoolz Air 625).

Of course, I'm just inferring the above conclusion.
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Old 05-26-12, 02:59 PM   #3
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Specialized used to make a "2-speed" pump (I forgot the model name). It had two cylinders one within the other. You started pumping with the big cylinder, and finished by locking it out and pumping with the inner one only. I always liked this pump and would recommend it to any woman asking about a floor pump.

I don't know if it's still made, but others have made similar items from time to time. If one still exists, it's probably your best bet. Otherwise there are few choices out there with cylinders having ID in the 1" to 1-1/16" range, but I don't know of anything smaller, except the compact frame pumps that double as floor pumps, but these are (IMO) too short and small, and the number of strokes would be a burden, except maybe as a topping off pump.
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Old 05-26-12, 03:02 PM   #4
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I became lazy long ago, when my racing silks required pumping before every day ride. So I built an electric pump from a discarded refrigerator compressor, fittings, pressure gauge, adjustable pressure release valve. Once the pressure release valve has been set, then just apply the pump until the release valve blows.
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Old 05-26-12, 05:04 PM   #5
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bontrager wsd pump. have not used it or looked at it closely but it was something i saw on the sales floor a few weeks ago
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Old 05-26-12, 05:30 PM   #6
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a child or light person shouldn't require 90psi for their bike...

It helps if the pump is oriented towards road cycling, as those have low volume, high compression pumps. MTB pumps are high volume, low compression and these are harder to get up to +90psi.



But there are techniques for using floor pumps.
What you do is lock your elbows and bend your knees so that most of your weight goes onto the pump.

That joe blow sport II is exactly what I use. I only weigh 130lbs, but I can easily get tires pumped up to 130psi with the above mentioned technique. I also only have below average upper strength. However, I only pump up my 23mm tires to 105psi.


lock elbows, bend knees.
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Old 05-26-12, 05:51 PM   #7
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What is the problem? Is it that your feet come off the floor before the desired pressure is reached? If so, just go to the bike shop and test out a few of the pumps. Don't know if that's possible in your case or not. You could get a small compressor and use it. I have a battery operated compressor with a digital display that you can set the pressure on. That would work but it would not be handy to carry on a ride.
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Old 05-27-12, 08:57 AM   #8
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Quote:
Originally Posted by FBinNY View Post
Specialized used to make a "2-speed" pump (I forgot the model name). It had two cylinders one within the other. You started pumping with the big cylinder, and finished by locking it out and pumping with the inner one only. I always liked this pump and would recommend it to any woman asking about a floor pump.
Good suggestion. Topeak makes the JoeBlow Ace http://www.topeak.com/products/Pumps/JoeBlowAce

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Originally Posted by reptilezs View Post
bontrager wsd pump. have not used it or looked at it closely but it was something i saw on the sales floor a few weeks ago
Thanks, that's what I am looking for. A local store has it listed on its web site. I will give it a try.

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Originally Posted by Makeitso View Post
What is the problem? Is it that your feet come off the floor before the desired pressure is reached?
It did not get to this point. Possibly the person did not have enough body strength to lift her 105lb.
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Old 05-27-12, 12:14 PM   #9
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Why not get a Silca pump? since you want to fit their connector head?

Note: it screws into a schrader hose end.. so The schrader fitting will already be there.

Last edited by fietsbob; 05-27-12 at 12:17 PM.
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Old 05-27-12, 12:36 PM   #10
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Why not get a Silca pump? since you want to fit their connector head?....
I think you missed the point. The issue isn't pump quality, but cylinder diameter. Or put another way, the ratio between force on the pump handle and pressure output.

A Silca has an ID of 1-1/16", as do most of the better HP floor pumps. This means that the input force is just about 1:1 with output pressure. (formula; input / (.8 x diameter˛) = output pressure, ie. 105#s on handle / (.8 x 1.125 x 1.125) = 105psi output (rounded for ease of calculation))

With a Silca pump it is physically impossible for a person to achieve a tire pressure in excess of his weight, and as a practical matter, difficult to exceed about 60-80% of ones weight. This is why women have so much trouble pumping tires. It isn't that they're weak, it,s that they are often just too light. The only way some women can get high pressure out of most floor pumps is to climb a ladded and jump down onto the pump handle (don't try this at home)
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Last edited by FBinNY; 05-27-12 at 12:54 PM.
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Old 05-27-12, 12:47 PM   #11
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But there are techniques for using floor pumps.
What you do is lock your elbows and bend your knees so that most of your weight goes onto the pump.105psi. lock elbows, bend knees.
Yep!

This way, you are using almost your whole bodyweight on the piston.
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Old 05-27-12, 01:17 PM   #12
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In general, it'd be good if they'd rate the pump as "force at handle to tire pressure", especially for mini pumps. I've bought a few mini pumps and they always say "up to xxx psi", but that may assume a gorilla is using it. I doubt I can reach 90 psi with my current mini pump that says up to "120 psi". I'm an average guy, but between poor ergonomics and fatigue and less than hulk strength, I'm never satisfied with mini pumps (I guess that's why they sell CO2 cartridge inflators).
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Old 05-27-12, 08:20 PM   #13
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We went today to the local store with a test wheel (Presta) and the bontrager WSD worked just fine so we bought it. The force difference from JoeBlow is noticeable. The pump itself is light and seems to be of decent quality and the stock valve worked well though I plan to replace with a Hirame valve.

http://bontrager.com/model/04525

Thanks everybody for the info.

Edit: the bontrager WSD ID is 26.5mm and the JoeBlow's is 29.20mm so the JoeBlow requires 21% additional force. I would expect a larger difference.

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