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 09-07-10, 12:03 PM   #1
finniam
Newbie
Thread Starter
 
Join Date: Sep 2010
Bikes:
Posts: 2
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
why can't i pump my tires!?

I have a brand new Specialized hybrid bike and just experienced my first flat (I got up this morning and my front tire was MAJORLY flat). I've only been riding on city roads, and my guess is they got a bit flat and pinched, probably my bad. So anyway I tried to pump it up, and my pump (a very nice new hp ground pump with gauge) says that I'm putting in air, and it becomes hard to pump, and yet my tire is flat as a pancake still.

I took off the tire, brought the tube out, did the best I could visually to find the hole and patched it (the place the looked to have a hole was indeed by the valve) and messed around with it a bit and still it wouldn't pump. I have a presta valve, and this pump is supposed to fit both types of valve anyway. I took the nut off of it and nothing has changed. Basically I've just fooled around with it a lot and don't know what to do!

I'm admittedly very new to bikes, I just got this one for school, so it could be a VERY SIMPLE and therefore embarrassing solution. If you have any advice, I would greatly appreciate it...
finniam is offline   Reply With Quote
Old 09-07-10, 12:13 PM   #2
kh6idf
Senior Member
 
Join Date: Dec 2009
Location: Phoenix, AZ
Bikes: Cervelo RS
Posts: 260
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Sometimes a presta valve will get stuck so it feels hard to pump and no air is actually going in the tire. I find this can be avoided by pushing down on the valve after it is unlocked to let a little air escape before attaching the pump. But in your case the tire is already flat so that may not be possible. The procedure for the presta valve is 1) remove the valve cap 2) unscrew the locking part all the way 3) attach pump per pump manufacturer's instructions and pump air into the tire. 4) remove pump and screw down the locking part. 5) screw on valve cap. Check your pump and be sure it is set up for presta valves. Mine can be set either way (presta or schrader) but came set up for presta.
kh6idf is offline   Reply With Quote
Old 09-07-10, 12:28 PM   #3
Doohickie 
You gonna eat that?
 
Doohickie's Avatar
 
Join Date: Sep 2008
Location: Fort Worth, Texas Church of Hopeful Uncertainty
Bikes: 1966 Raleigh DL-1 Tourist, 1973 Schwinn Varsity, 1983 Raleigh Marathon, 1994 Nishiki Sport XRS
Posts: 14,360
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 13 Post(s)
Yeah, if you have a Presta valve and are used to Schrader valves (like what they have on cars), there is a little different techinque to filling up a tire.

On a Schrader, a spring seals the valve to keep air from escaping. To pump up a Schrader valve, you have have a pump head that pushes the valve open (by pushing on the little metal piece in the middle). You have to make sure the pump head has gone on far enough to push that piece.

With a Presta, there are two things holding the valve closed: 1) there is a little knurled nut on the end of the plunger that holds the plunger in the closed position. You have to loosen that nut (it's on the tip of the valve, under the plastic valve cap). 2) Any air pressure in the tube will also push the valve shut. Or in some cases, the valve is stuck shut just because it hasn't been opened in a long time. So once you loosen the knurled nut, it's a good idea to tap the end of the valve to make sure the plunger moves and the valve isn't stuck. One thing you don't have to do, though, is hold the valve open (like with a Schrader valve). As long as there is more pressure outside the valve than inside, the valve will open to allow air in.

So... to fill a Presta valve tube:

1. Remove the plastic valve cap.
2. Loosen the brass knurled nut on the end of the valve plunger.
3. Push the plunger in to make sure the valve isn't stuck.
4. Line up the pump head and push it over the valve; you don't have to push it "all the way" to depress the valve though.
5. Lock the pump head in place.
6. Pump up the tire.
7. Release the pump head and remove the pump from the valve.
8. Tighten the knurled nut on the end of the plunger.
9. Put the plastic valve cap back on.

It's not really as complicated as nine steps would indicate, but if you're accustomed to automotive style Schrader valves, Presta valves take a little getting used to. When I first started with them, sometimes I would forget to loosen the knurled nut; other times I tired to push the pump head onto the valve far enough to push the plunger. Neither of these methods led to success. I was convinced the pump was broken. Once I did it right it occurred to me that I was trying to fill it like a Schrader valve. Duh.
__________________
I stop for people / whose right of way I honor / but not for no one.



Originally Posted by bragi "However, it's never a good idea to overgeneralize."
Doohickie is offline   Reply With Quote
Old 09-12-10, 01:24 PM   #4
rojeho
Senior Member
 
Join Date: Dec 2009
Location: Palm Harbor, FL
Bikes: 2010 Specialized Sirrus Sport, 2005 Specialized Dolce
Posts: 52
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
I just discovered the same problem this morning. My first experience with Presta Valves. I have a pump with a PV adapter. My question is when am I supposed to see a pressure reading on the pump gauge? When I first make the connection or after I pump a few times? Even when I pumped after 4-6 pumps it would show some pressure, but as soon as I stopped the gauge went back to zero.

Before I buy a new pump I want to make sure that I'm not doing something fundamentally wrong. I am following the instructions in the post and it seems like it should work....
rojeho is offline   Reply With Quote
Old 09-12-10, 01:57 PM   #5
wrk101
DRF aka Thrifty Bill
 
wrk101's Avatar
 
Join Date: Jan 2008
Location: The NC Mountains
Bikes: 86 Katakura Silk, 87 Prologue, 87 Cimarron, 14 frame school custom, 73 Paramount
Posts: 19,976
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 8 Post(s)
Quote:
Originally Posted by rojeho View Post
I just discovered the same problem this morning. My first experience with Presta Valves. I have a pump with a PV adapter. My question is when am I supposed to see a pressure reading on the pump gauge? When I first make the connection or after I pump a few times? Even when I pumped after 4-6 pumps it would show some pressure, but as soon as I stopped the gauge went back to zero.

Before I buy a new pump I want to make sure that I'm not doing something fundamentally wrong. I am following the instructions in the post and it seems like it should work....
I don't usually see a reading on a totally flat tire for the first few pump strokes.

It sounds like you don't have the pump head fully seated. Air is probably leaking around the pump head. Or leaking around the gauge. Borrow a pump from a friend, or better yet, have a friend who is bike knowledgeable use your pump.
wrk101 is offline   Reply With Quote
Old 09-12-10, 02:05 PM   #6
10 Wheels
Galveston County Texas
 
10 Wheels's Avatar
 
Join Date: Nov 2007
Location: In The Wind
Bikes: 2010 Expedition, 03 GTO
Posts: 29,677
Mentioned: 5 Post(s)
Tagged: 0 Thread(s)
Quoted: 230 Post(s)
How too:
http://www.ehow.com/video_6204021_use-bicycle-pump.html
__________________
[SIZE=1][B]What I like about Texas[/B]
http://www.youtube.com/watch?v=PGukLuXzH1E

Set F1re To The Ra1n ( NY Night Rain Ride)
http://www.youtube.com/watch?v=W7jfcWEkSrI
10 Wheels is online now   Reply With Quote
Old 09-12-10, 09:27 PM   #7
Black Sunshine
Desert Flatlander
 
Join Date: Jan 2009
Location: Buckeye, AZ
Bikes: 2001 Trek Alpha 1000, Micargi Tahiti NX3 'The Iron Horse', and many other cheap resale and family bikes.
Posts: 80
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
One easy way to get around silly presta problems is an adapter: http://www.amazon.com/Innovations-In...4348230&sr=8-1

My pump is very fickle. It's supposed to work for both without alteration, which in itself doesn't make sense.
  1. I remove the presta valve cap,
  2. loosen the knurled nut,
  3. push the knurled nut once to make sure it's not stuck,
  4. screw on the adapter,
  5. fill like any other valve.
Black Sunshine is offline   Reply With Quote
Old 09-13-10, 04:35 AM   #8
ThinkICO
Junior Member
 
Join Date: Jul 2010
Location: Mossley Greater Manchester UK
Bikes:
Posts: 16
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Just to double check and I know that this should be obvious... but most pumps that fit Schrader and Presta are set for one or the other and require an adjustment to fit the other valve type... Normally this just includes unscrewing the pump connector flipping the insert over and screwing it back together.
ThinkICO is offline   Reply With Quote
Old 09-13-10, 08:49 AM   #9
nhluhr
John Wayne Toilet Paper
 
nhluhr's Avatar
 
Join Date: Feb 2006
Location: Roanoke
Bikes: BH carbon, Ritchey steel, Kona aluminum
Posts: 1,950
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by Black Sunshine View Post
One easy way to get around silly presta problems is an adapter: http://www.amazon.com/Innovations-In...4348230&sr=8-1

My pump is very fickle. It's supposed to work for both without alteration, which in itself doesn't make sense.
  1. I remove the presta valve cap,
  2. loosen the knurled nut,
  3. push the knurled nut once to make sure it's not stuck,
  4. screw on the adapter,
  5. fill like any other valve.
Why don't you just learn how to use a presta valve and pump? Seems like you waste a lot of time/effort with your roundabout method.
nhluhr is offline   Reply With Quote
Old 09-14-10, 11:43 AM   #10
finniam
Newbie
Thread Starter
 
Join Date: Sep 2010
Bikes:
Posts: 2
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Thank you all so much for your feedback. You definitely clarified the differences for me, which has proved quite helpful and made me look like a stud when I explained it to someone else a few days ago.

Still though, I couldn't get my front tire pump and I eventually took it to a bike shop where they had no problem pumping my tire, which was weird (and frustrating) because my pump worked for me on my OTHER tire, demonstrating it wasn't my pump, and they had demonstrated it wasn't the tire... so it was all a big mess.

Eventually I got my pump to work by just pushing the pump head down quite hard onto the valve (much harder than needed for my back tire). I also bought an adaptor while at the shop for $1 which makes it easier as well, even though I technically don't need it.

So moral of the story... if anyone else has this problem... try pushing just a little harder, haha.
finniam is offline   Reply With Quote
Old 09-14-10, 03:20 PM   #11
robtown
Muscle bike design spec
 
robtown's Avatar
 
Join Date: Oct 2004
Location: Sterling VA
Bikes: 70 Atala Record Proffesional, 00 Lemond, 08 Kestrel Evoke, 96 Colnago Master Olympic, 01 Colnago Ovalmaster, 76 Raleigh Gran Sport, 03 Fuji World, 86 Paramount, 90 Miyata CF, 09 Ritchey Breakaway CX, Bianchi Trofeo, 12 OutRiderUSA HyperLite
Posts: 3,668
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Besides the good advice already given - I've seen one other issue. Sometimes when the tire is completely flat I can pump without the tube inflating at all. I found that putting pressure on the tire pushing upwards directly beneath the valve allows the tube to start inflating. After the first pump with pressure applied the tube fills properly.

Quote:
Originally Posted by finniam View Post
Thank you all so much for your feedback. You definitely clarified the differences for me, which has proved quite helpful and made me look like a stud when I explained it to someone else a few days ago.

Still though, I couldn't get my front tire pump and I eventually took it to a bike shop where they had no problem pumping my tire, which was weird (and frustrating) because my pump worked for me on my OTHER tire, demonstrating it wasn't my pump, and they had demonstrated it wasn't the tire... so it was all a big mess.

Eventually I got my pump to work by just pushing the pump head down quite hard onto the valve (much harder than needed for my back tire). I also bought an adaptor while at the shop for $1 which makes it easier as well, even though I technically don't need it.

So moral of the story... if anyone else has this problem... try pushing just a little harder, haha.
__________________
Korval is Ships
See my Hyperlite 411 it's the photo model on OutRiderUSA web page
robtown 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 09:53 PM.