Cycling and bicycle discussion forums. 
   Click here to join our community Log in to access your Control Panel  


Go Back   > >

Bicycle Mechanics Broken bottom bracket? Tacoed wheel? If you're having problems with your bicycle, or just need help fixing a flat, drop in here for the latest on bicycle mechanics & bicycle maintenance.

User Tag List

Reply
 
Thread Tools Search this Thread
Old 08-08-06, 08:51 PM   #1
yiwca
Newbie
Thread Starter
 
Join Date: Aug 2006
Bikes:
Posts: 1
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
need help about pumping tires

I know this will sound dumb but I'm really clueless. I have a mountain bike with tires that have lost pressure since it's been sitting unused for 7 months. I got a floor pump with pressure gauge and tried to inflate the tires but although the recommended pressure is 40-65 psi, I can't seem to pump them to that pressure. At around 25 psi the tires already felt very hard and the pump got really hard to push. I didn't want to push the pump too hard because I was worried the tires might explode. Should I pump more air no matter how hard the tires feel and just trust the pressure gauge?
yiwca is offline   Reply With Quote
Old 08-08-06, 09:32 PM   #2
mactheknife68
Always find my way home
 
Join Date: Dec 2005
Location: Kankakee, IL
Bikes: Madone, 8500
Posts: 190
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Got a pencil guage in your glovebox? See if the readings match.
mactheknife68 is offline   Reply With Quote
Old 08-08-06, 11:19 PM   #3
moxfyre
cyclist/gearhead/cycli...
 
moxfyre's Avatar
 
Join Date: Oct 2004
Location: DC / Maryland suburbs
Bikes: Homebuilt tourer/commuter, modified-beyond-recognition 1990 Trek 1100, reasonably stock 2002-ish Gary Fisher Hoo Koo E Koo
Posts: 4,166
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by yiwca
I know this will sound dumb but I'm really clueless. I have a mountain bike with tires that have lost pressure since it's been sitting unused for 7 months. I got a floor pump with pressure gauge and tried to inflate the tires but although the recommended pressure is 40-65 psi, I can't seem to pump them to that pressure. At around 25 psi the tires already felt very hard and the pump got really hard to push. I didn't want to push the pump too hard because I was worried the tires might explode. Should I pump more air no matter how hard the tires feel and just trust the pressure gauge?
Typically, tires should be pumped hard enough that if you squeeze them with your thumb, you'll make a small dent, but it will be hard to do. Furthermore, when you sit on the bike, the tires should "squish" a bit around the bottom, but not so much that the rim will ever bottom out by riding. Inflating the tires to this level gives you a comfortable ride, with a minimum of friction.

By the way, it's basically impossible to "explode" a bike tire, since the tire itself is much stronger than the airtight inner tube. The worst that can normally happen is that you will pop a hole in the inner tube, which is easy to patch or to replace (a new inner tube usually costs $3-5). The other problem with overinflating your tires is that it will make the ride very uncomfortable and jarring, because the tire will hardly flex at all as you go over bumps.

Hope this helps you to pump up your tires without worrying too much about the pressure gauge
moxfyre is offline   Reply With Quote
Old 08-09-06, 05:14 AM   #4
lrzipris
Senior Member
 
Join Date: Sep 2002
Location: Philadelphia suburb
Bikes:
Posts: 911
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Tires rated 40-65 getting that hard at only 25 psi...hmm, sounds odd. My guess is the pump's gauge is way off, so take mactheknife68's advice. If you don't have a gauge, borrow a pump and see if you have the same problem.
lrzipris is offline   Reply With Quote
Old 08-09-06, 05:46 AM   #5
frankiee
Senior Member
 
Join Date: Jun 2005
Location: Ontario Canada
Bikes: Iron Horse Axion; Other box store stuff
Posts: 80
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Yes. Get another gauge.
frankiee is offline   Reply With Quote
Old 08-09-06, 05:58 AM   #6
fordfasterr
One speed: FAST !
 
fordfasterr's Avatar
 
Join Date: Dec 2005
Location: Ft. Lauderdale FL
Bikes: Ebay Bikes... =)
Posts: 3,375
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
I have a problem within the inflation realm...

I bought a new manual pump, the guage on it goes up to 260 psi. It has a wooden handle (brand new) and I've seen other people at the track with the same pump so I figured it was good...

I just put together a new mavic wheelset and installed some tufo's ... I had to use a valve extender because the stem was not long enough... so I stick this pump thing on it (no latch on the inflation fitting), just a rubber grommet thing in there... I start to pump away and at first nothing happens...

Then it catches and starts to hold air, but it leaks it out almost as fast as I can pump it back in.. I kept fighting it and got about 100 psi into it... after like 30 pumps !! ....

I tried it with the 2nd wheel and had the same issue, what am I doing wrong? How can I fix this?
fordfasterr is offline   Reply With Quote
Old 08-09-06, 06:15 AM   #7
LóFarkas
LF for the accentdeprived
 
Join Date: May 2005
Location: Budapest, Hungary
Bikes:
Posts: 3,549
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by mactheknife68
Got a pencil guage in your glovebox? See if the readings match.
+1 Ride the bike to a gas station and check it there if you don't have one.
LóFarkas is offline   Reply With Quote
Old 08-11-06, 04:17 AM   #8
trmcgeehan
Senior Member
 
trmcgeehan's Avatar
 
Join Date: Oct 2002
Location: Somerset, KY -- near Lake Cumberland
Bikes: 1980 Univega; 1985 Ross; 1994 Trek 1400 -- all road bikes
Posts: 757
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Hose end

Sounds like you may not have the air hose end pushed down far enough on the valve stem.
__________________
"I am a true laborer. I earn that I eat, get that I wear, owe no man hate, envy no man's happiness, glad of other men's good, content with my harm." As You Like It, Act 3, Scene 2. Shakespeare.
"Deep down, I'm pretty superficial." Ava Gardner.
trmcgeehan is offline   Reply With Quote
Old 08-11-06, 04:24 AM   #9
mudskipper99
Senior Member
 
mudskipper99's Avatar
 
Join Date: Jul 2006
Location: Ann Arbor, MI
Bikes: 2001 Schwinn Mesa Gsx
Posts: 105
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by yiwca
I know this will sound dumb but I'm really clueless. I have a mountain bike with tires that have lost pressure since it's been sitting unused for 7 months. I got a floor pump with pressure gauge and tried to inflate the tires but although the recommended pressure is 40-65 psi, I can't seem to pump them to that pressure. At around 25 psi the tires already felt very hard and the pump got really hard to push. I didn't want to push the pump too hard because I was worried the tires might explode. Should I pump more air no matter how hard the tires feel and just trust the pressure gauge?
I just posted not to long ago with basicly the same question. I pumped as much air into the tires as I could, yet the pressure in the tires was way too low. Turned out I had a cheap pump, that couldnt pump enough air into the tires. Do you have a good pump. I had a cheap one from Miejers (like Walmart store). If you look through my posts, clicking on my avatar, look at "confused about air pressure gauges".
mudskipper99 is offline   Reply With Quote
Old 08-11-06, 10:11 AM   #10
Mach42
Senior Member
 
Join Date: Sep 2005
Location: Salt Lake City, UT
Bikes: 2005 Scattante R660 Triple, 2006 Specialized Rockhopper Comp Disc
Posts: 643
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
It was insane trying to pump up my MTB tires to 40 psi with a Walmart Bell pump. Once I got a decent Serfas floor pump, it was really easy to do, and taking it up to 120 psi on my road bike is a piece of cake. The Bell pump is only good for Walmart tires with a max of 30-40 psi.
Mach42 is offline   Reply With Quote
Old 08-11-06, 11:00 AM   #11
peripatetic
Senior Member
 
peripatetic's Avatar
 
Join Date: Oct 2004
Location: NYC
Bikes: All 70s and 80s, only steel.
Posts: 2,124
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
I just bought a Topeak Joe Blow pump. Nothing beats a good pump...nothing.
peripatetic is offline   Reply With Quote
Old 08-11-06, 11:08 AM   #12
Gonzo Bob
cycles per second
 
Gonzo Bob's Avatar
 
Join Date: Oct 2003
Location: Minnesota
Bikes: Vitus Aluminum, DiamondBack Apex, Softride Powerwing 700, "Generic" Ishiwata 022, Trek OCLV 110
Posts: 1,790
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by fordfasterr
Then it catches and starts to hold air, but it leaks it out almost as fast as I can pump it back in.. I kept fighting it and got about 100 psi into it... after like 30 pumps !! ....
Are you sure it's leaking out of the tire? Normally the tire pressure closes the presta valve and the leaking you get is actually out of the pump because of an imperfect seal at the valve stem. Since you are using valve extenders, it could leak out at the chuck or at the extender/valve interface. Many folks use teflon tape on the valve stem when using valve extenders to give a better seal there.

Another possibility is if the valve stem is bent, it might be binding against the inside wall of the valve extender not allowing it to close all the way after each pump.
Gonzo Bob is offline   Reply With Quote
Old 08-11-06, 03:19 PM   #13
AndrewP
Senior Member
 
Join Date: Sep 2001
Location: Montreal
Bikes: Peugeot Hybrid, Minelli Hybrid
Posts: 6,521
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
A pump with a small diameter barrel is much easier to get high pressures. It may take more strokes to reach any given pressure, but you will be sure of reaching the pressure you want.
AndrewP is offline   Reply With Quote
Old 08-11-06, 04:48 PM   #14
masiman
Senior Member
 
Join Date: Oct 2005
Bikes:
Posts: 1,735
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by peripatetic
Nothing beats a good pump...nothing.
In tires and love....I'll shut up now.
masiman is offline   Reply With Quote
Old 08-11-06, 05:09 PM   #15
ZachS
\||||||/
 
ZachS's Avatar
 
Join Date: Mar 2006
Location: pdx
Bikes: highly modified specialized crossroads and GT hybrid (really a [formerly] 12-speed bmx cruiser, made before 'hybrid' took on its current meaning), as yet unmodified redline 925, couple of other projects
Posts: 1,360
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
it's spelled

GAUGE

seriously.
ZachS is offline   Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off



All times are GMT -6. The time now is 12:29 AM.