Road Bike, Cycling Forums banner
1 - 4 of 4 Posts

· Registered
Joined
·
68 Posts
Discussion Starter · #1 ·
I have a michelin floor pump and its hard to get a good reading from the gauge. The needle kind of jumps to the different pressures. It is not smooth and is hard to get to the correct pressure. Is this normal or is there something wrong, or am i doing something wrong? Do I need a better pump or something?
 

· Registered
Joined
·
211 Posts
I am guessing you are not getting the pump seated correctly on the valve. If you quickly go up past 100 pounds its probably not seated on the valve correctly and no air went into the tube. Sometimes I just let all the air out and push the pump head firmly onto the valve and pump it all the way back up. It should go smoothly up on the gauge and it should be tight enough that air isnt seeping out. My last two pumps have been kind of cheap and after using a few friends pumps and shop pumps I think it might be worth it to spend a few bucks more.
 

· Chili hed & old bike fixr
Joined
·
1,197 Posts
Go ahead and invest in your last floor pump, a SILCA every part is available and easy to install. Use smooth valve stems and replace the chuck washer every 3-4 years. One of the last great, durable products.
 

· Registered
Joined
·
14,776 Posts
There may be nothing wrong

n1civicsi said:
The needle kind of jumps to the different pressures.
If you're not familiar with how presta valves work, it may look strange. Is this what you're seeing:
-- when you pump, the gauge needle goes up to a high pressure, then quickly (maybe with a popping or clicking sound) drops to a lower pressure, maybe wobbles for a second, then stabilizes. When you pump another stroke, it does the same thing again, but stops at a higher pressure than the last stroke.

If that's what you're seeing, everything is probably working fine. With a presta valve, there's no spring holding the tube's valve open. To put in air, the pump must build up enough pressure to force the valve open, then when the valve opens the excess pressure is forced into the tire, then the tire's pressure pushes the valve closed again. The level at which the needle stabilizes each time corresponds to the pressure in the tire, and that's all you need to worry about.

It should not be necessary to let significant air out of the tire before you pump, but it's a good idea to push the valve stem down very briefly after you loosen the locknut, just to get the valve "unstuck". After that, you should see the pattern I described above.

In my experience, it's common for the gauge to go up well past 100 PSI before the first dose goes in. There's nothing wrong with this, and it does not indicate that the pump head is inadequately seated. In fact, if the pump head isn't on right the air will escape and you'll get no sustained reading (the gauge will go up then quickly leak back down). The only ways you'll get very high readings with no air going into the tire are if you forget to loosen the locknut or the valve is very stuck. Let out a tiny bit of air to unstick it and you're good to go.
 
1 - 4 of 4 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top