Mini Pump

Lou Holtman wrote:
Op dinsdag 11 mei 2021 om 15:07:24 UTC+2 schreef AMuzi:
On 5/10/2021 9:26 PM, James wrote:
On 11/5/21 9:29 am, jbeattie wrote:
On Monday, May 10, 2021 at 4:12:22 PM UTC-7, James wrote:
On 10/5/21 6:45 pm, Lou Holtman wrote:


100 psi easily achieved with a minipump? I don't believe
that.
Did you ever checked that?

Yes Lou. I tested it years ago, but for you I tried
again. To save time I pumped my front 23mm tyre to 100psi
using my Silca floor
pump, then attached my Lezyne Road Drive mini pump and
applied
another 40 strokes. Then I reconnected my Silca floor
pump and
checked the pressure. It was near to 120psi.

You must have strong arms -- but really short arms like a
T-Rex. I
think T-Rex arms would be perfect for a mini-pump.

I could probably get that pressure with my Road Morph with
the pump
on the ground and the mini foot-peg extended, but not
with my
various other mini-pumps. 80-90PSI would be a big win.



I stand about 190cm tall and my arm span is similar if not
more. So no, I don't have short arms. I'm not very bulky
either, at about 75kg.

I don't think my arms are very strong. I certainly can't do
many pushups. Maybe 10?

I read somewhere that the road drive is 17mm dia. Maybe the
internal dia is 15mm? That is about 177mm^2. 100psi is
689476 Pa, which is Newtons / m^2. Converting to N /
177mm^2 is 121.84N, or 12.4kg of force to achieve 100psi.

I can't be bothered going out to measure precisely, but I
think my calcs are in the ball park. I'd be happy for
someone to verify. Frank?

Probably close enough, considering your report of 'not
extreme effort'.
--
Andrew Muzi
www.yellowjersey.org/
Open every day since 1 April, 1971


It is not only the force you have to apply but also the 'effective'
stroke at the end. If you have to increase the pressure from 1 bar to 7
bar the pressure of 7 bar is reached only at 1/7 th of the total stroke.
Mini/clown pumps have a stroke of around 15 cm only the last 2 cm of that
stroke is effective at the end. So going from 6.5 bar to 7 bar takes a
lot of strokes. Most people find that too troublesome and stop at a
pressure of 5-6 bar. With a 16 gr CO2 cartrigde you get 6.5 bar in a
couple of seconds without any effort in a 25 mm tire. If you carry a
clown pump only use it when you run out of CO2 catridges. When you carry
2 tubes and 2 CO2 cartridges carrying a clown pump is only usefull if you
also carry a patch kit. It is something like carrying a quick link without a chain tool.

Lou


I use the clown pump to find the hole in the tube to get a better idea of
where to check the tire for glass shards or whatever caused the flat.
Otherwise I agree.

AMuzi wrote:
On 5/11/2021 9:29 AM, Ralph Barone wrote:
AMuzi wrote:
On 5/10/2021 6:12 PM, James wrote:
On 10/5/21 6:45 pm, Lou Holtman wrote:
Op maandag 10 mei 2021 om 07:45:24 UTC+2 schreef James:
On 10/5/21 11:50 am, Frank Krygowski wrote:

It might be handy to see a chart of "pump strokes to 100
psi"
for various brands and models, starting from an empty tube.


Don't forget effort (force) to achieve said pressure.

Diameter and length affects volume / stroke.

Diameter also affects force @ pressure.

To minimize force and strokes, opt for smaller diameter
and longer
barrel.

However - is it still a "mini pump" with a long barrel?

I've got a Lezyne road drive pump for my road bike with
up to 25mm
tyres @ 100psi, and a higher volume Lezyne pump for my
gravel bike
that has 42mm tyres @ 50psi.

100psi is easily achievable for the road bike, but I
wouldn't want
to use the larger diameter & volume gravel bike pump to
reach
100psi, though it might take fewer strokes.


100 psi easily achieved with a minipump? I don't believe
that. Did
you ever checked that?


Yes Lou. I tested it years ago, but for you I tried again.
To save time I pumped my front 23mm tyre to 100psi using my
Silca floor pump, then attached my Lezyne Road Drive mini
pump and applied another 40 strokes. Then I reconnected my
Silca floor pump and checked the pressure. It was near to
120psi.




The manufacturer humbly notes that this is the best product
humans have ever made:
https://ride.lezyne.com/products/1-mp-rddr-v2l04

But under 'specs' doesn't list the piston diameter which is
the crucial dimension.

A one-square-inch piston (1-1/4" dia) needs 100 lbs of
muscle to make 100psi. A half-inch diameter needs about 20
pounds (and 5x number of strokes if the length is the same)



I’ve thought that somebody needs to make a pump with a “piston inside a
piston� - ie: a cylindrical piston that slides in a ring shaped piston.
Have the pump handle drive the inner piston, but couple it to the outer
ring shaped piston through a spring. That way, when pressure is low, both
pistons move as one and you deliver high volume at low pressure. As
pressure rises, the outer piston would tend to stay in one place and you
would convert to a high pressure, low volume setup. I’ve never put the
effort in to put this on paper or build a prototype, but the parts all seem
to do the right thing in my mind.



It's been done. Failed as a product but it worked as you
described:

http://www.yellowjersey.org/photosfr...%231pmp_in.gif


And it pumped air on the return stroke as well. Interesting design. I
wonder why it failed in the market. Overpriced, unreliable or just badly
marketed?

On 5/11/2021 8:37 PM, Ralph Barone wrote:
AMuzi wrote:
On 5/11/2021 9:29 AM, Ralph Barone wrote:

I’ve thought that somebody needs to make a pump with a “piston inside a
piston� - ie: a cylindrical piston that slides in a ring shaped piston.
Have the pump handle drive the inner piston, but couple it to the outer
ring shaped piston through a spring. That way, when pressure is low, both
pistons move as one and you deliver high volume at low pressure. As
pressure rises, the outer piston would tend to stay in one place and you
would convert to a high pressure, low volume setup. I’ve never put the
effort in to put this on paper or build a prototype, but the parts all seem
to do the right thing in my mind.



It's been done. Failed as a product but it worked as you
described:

http://www.yellowjersey.org/photosfr...%231pmp_in.gif


And it pumped air on the return stroke as well. Interesting design. I
wonder why it failed in the market. Overpriced, unreliable or just badly
marketed?

This is a memory many decades old, but I thought my bike shop owning
friends said they came back broken. As I recall, it was astonishingly
light - probably into the "stupid light" category.

--
- Frank Krygowski

On Tuesday, May 11, 2021 at 6:19:34 PM UTC-7, Frank Krygowski wrote:
On 5/11/2021 8:37 PM, Ralph Barone wrote:
AMuzi wrote:
On 5/11/2021 9:29 AM, Ralph Barone wrote:

I’ve thought that somebody needs to make a pump with a “piston inside a
piston� - ie: a cylindrical piston that slides in a ring shaped piston.
Have the pump handle drive the inner piston, but couple it to the outer
ring shaped piston through a spring. That way, when pressure is low, both
pistons move as one and you deliver high volume at low pressure. As
pressure rises, the outer piston would tend to stay in one place and you
would convert to a high pressure, low volume setup. I’ve never put the
effort in to put this on paper or build a prototype, but the parts all seem
to do the right thing in my mind.



It's been done. Failed as a product but it worked as you
described:

http://www.yellowjersey.org/photosfr...%231pmp_in.gif


And it pumped air on the return stroke as well. Interesting design. I
wonder why it failed in the market. Overpriced, unreliable or just badly
marketed?
This is a memory many decades old, but I thought my bike shop owning
friends said they came back broken. As I recall, it was astonishingly
light - probably into the "stupid light" category.

Yes, ridiculously light. https://www.flickr.com/photos/zbills...7606789001880/ (4.5 oz). The clear plastic looked cheap, and at the time, I was using Silca Impero pumps -- typically painted to match my frame, because I was a snob.

-- Jay Beattie

On 11/5/21 11:26 pm, Lou Holtman wrote:


It is not only the force you have to apply but also the 'effective'
stroke at the end. If you have to increase the pressure from 1 bar to
7 bar the pressure of 7 bar is reached only at 1/7 th of the total
stroke. Mini/clown pumps have a stroke of around 15 cm only the last
2 cm of that stroke is effective at the end. So going from 6.5 bar to
7 bar takes a lot of strokes. Most people find that too troublesome
and stop at a pressure of 5-6 bar. With a 16 gr CO2 cartrigde you get
6.5 bar in a couple of seconds without any effort in a 25 mm tire.

No debate.

If
you carry a clown pump only use it when you run out of CO2 catridges.
When you carry 2 tubes and 2 CO2 cartridges carrying a clown pump is
only usefull if you also carry a patch kit. It is something like
carrying a quick link without a chain tool.


I have he1ped people on a few occasions with my clown pump, who insist
on only carrying compressed clown farts and tubes.

I carry a quick link and a chain tool too, and on my gravel bike a tube
and a patch kit. ;-) My chain tool is integrated with my multitool.
It also has a spoke key for various nipple sizes, and that has been
borrowed by a few people too.

I have *never* required help from anyone. I like being self sufficient.
There is a lot of empty road around where I live, and not many people
to ride with either!

--
JS

On 12/5/21 12:18 am, jbeattie wrote:


I call it "inflation inflation" -- the irrational fear of being
without inflation. It is the result of fear mongering by the
mini-pump cartel.

As a person who has bought into inflation inflation, my only tip is
to make sure that the pump works. You can go a long time between
actually using a pump, washers can dry out and small parts fall off,
etc., etc., and when you go to use the pump, it is useless or turns
into its own roadside repair project.


I've watched people stuff up the inflation of a tyre with compressed
clown farts too. My tip would be to practice at home a few times at
least. Compressed clown farts don't cost very much.

--
JS

Frank Krygowski wrote:
On 5/11/2021 8:37 PM, Ralph Barone wrote:
AMuzi wrote:
On 5/11/2021 9:29 AM, Ralph Barone wrote:

I’ve thought that somebody needs to make a pump with a “piston inside a
piston� - ie: a cylindrical piston that slides in a ring shaped piston.
Have the pump handle drive the inner piston, but couple it to the outer
ring shaped piston through a spring. That way, when pressure is low, both
pistons move as one and you deliver high volume at low pressure. As
pressure rises, the outer piston would tend to stay in one place and you
would convert to a high pressure, low volume setup. I’ve never put the
effort in to put this on paper or build a prototype, but the parts all seem
to do the right thing in my mind.



It's been done. Failed as a product but it worked as you
described:

http://www.yellowjersey.org/photosfr...%231pmp_in.gif


And it pumped air on the return stroke as well. Interesting design. I
wonder why it failed in the market. Overpriced, unreliable or just badly
marketed?

This is a memory many decades old, but I thought my bike shop owning
friends said they came back broken. As I recall, it was astonishingly
light - probably into the "stupid light" category.


So maybe “designed past the optimum...�. Sometimes it’s hard to drop
optimizing something when you’re in a design frame of mind.

On 12/5/21 3:09 am, Bertrand wrote:

If you carry a clown pump only use it when you run out of CO2
catridges. When you carry 2 tubes and 2 CO2 cartridges carrying a
clown pump is only usefull if you also carry a patch kit. It is
something like carrying a quick link without a chain tool.

I had a CO2 inflator fail once (due to corrosion) so always carry a tiny
pump now as a backup.


Inflation inflation - just as Jay described!

--
JS

Ralph Barone wrote:
Frank Krygowski wrote:
On 5/11/2021 8:37 PM, Ralph Barone wrote:
AMuzi wrote:
On 5/11/2021 9:29 AM, Ralph Barone wrote:

I’ve thought that somebody needs to make a pump with a “piston inside a
piston� - ie: a cylindrical piston that slides in a ring shaped piston.
Have the pump handle drive the inner piston, but couple it to the outer
ring shaped piston through a spring. That way, when pressure is low, both
pistons move as one and you deliver high volume at low pressure. As
pressure rises, the outer piston would tend to stay in one place and you
would convert to a high pressure, low volume setup. I’ve never put the
effort in to put this on paper or build a prototype, but the parts all seem
to do the right thing in my mind.



It's been done. Failed as a product but it worked as you
described:

http://www.yellowjersey.org/photosfr...%231pmp_in.gif


And it pumped air on the return stroke as well. Interesting design. I
wonder why it failed in the market. Overpriced, unreliable or just badly
marketed?

This is a memory many decades old, but I thought my bike shop owning
friends said they came back broken. As I recall, it was astonishingly
light - probably into the "stupid light" category.


So maybe “designed past the optimum...�. Sometimes it’s hard to drop
optimizing something when you’re in a design frame of mind.



.... stop optimizing...
See. I just HAD to make that a little bit better.

Op woensdag 12 mei 2021 om 04:37:15 UTC+2 schreef James:


I have he1ped people on a few occasions with my clown pump, who insist
on only carrying compressed clown farts and tubes.

It seems that I am the only one that seen more mini pumps fail when they were needed than my CO2 inflator. In more than a few occasions during group rides I helped people out of their mini pump misery offering one of my CO2 cartidges.


I have *never* required help from anyone. I like being self sufficient.
There is a lot of empty road around where I live, and not many people
to ride with either!

I too like to be self sufficient and maybe I'm was lucky so far. I think the most important is to keep your bike and gear in good condition and that includes spare tubes and minpump/CO2 inflator and know how to operate them.

Lou