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 07-31-05, 07:35 PM   #1
Post42K
Senior Member
Thread Starter
 
Join Date: Jul 2003
Location: Northern VA
Bikes:
Posts: 185
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Pump head pops off with threadless presta valve?

I just installed a new Michelin tube with a threadless presta valve. When I try pumping the tire, the head of the pump pops off when the PSI reaches about 100. The seal doesn't seem to be gripping the valve tightly when I lock it. I've only used threaded tubes before and never had this problem. Could the seal be worn from the threaded valves? The pump is a Topeak Joe Blow Sport but it's only 3 months old and used twice a week. Is there anyway to fix this? Thanks for the input!
Post42K is offline   Reply With Quote
Old 07-31-05, 07:59 PM   #2
PWRDbyTRD
Toyota Racing Dev.
 
PWRDbyTRD's Avatar
 
Join Date: Oct 2004
Location: Knoxville, TN baby!
Bikes: 2004 Kona Hoss Dee-Lux
Posts: 3,339
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Topeak offers rebuilt kits for most of their pumps, also are you sure the pump is compatible with a threadless valve?
PWRDbyTRD is offline   Reply With Quote
Old 07-31-05, 08:23 PM   #3
Al1943
Senior Member
 
Join Date: Feb 2005
Location: Oklahoma
Bikes: Trek 5500, Colnago C-50
Posts: 9,433
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Are you sure you have the chuck latch in the correct position?

You may need a new "O" ring or whatever is inside the chuck.

I use a Joe Blow with Michelin tubes.
Al1943 is offline   Reply With Quote
Old 07-31-05, 08:49 PM   #4
Post42K
Senior Member
Thread Starter
 
Join Date: Jul 2003
Location: Northern VA
Bikes:
Posts: 185
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
are you sure the pump is compatible with a threadless valve?

I believe it is but not 100% sure. Are there pumps made specifically for threadless valves?

Are you sure you have the chuck latch in the correct position?

Yes, it still works fine with the threaded valves.

I'm just surprised that after 3 months the parts would wear out. Does anyone else use their pump on both threaded and threadless valves without problems?
Post42K is offline   Reply With Quote
Old 07-31-05, 09:29 PM   #5
jsharr
You Know!? For Kids!
 
jsharr's Avatar
 
Join Date: Apr 2005
Location: Just NW of Richardson Bike Mart
Bikes: '05 Trek 1200 / '90 Trek 8000 / '? Falcon Europa
Posts: 6,157
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 3 Post(s)
there is a threaded ring on the head of the pump, it compresses a seal around the stem, which is even further compressed when the pump head lever is closed. Try giving the ring a turn or two if possible, to increase sealing pressure of the pump head onto the stem.
__________________
Are you a registered member? Why not? Click here to register. It's free and only takes 27 seconds! Help out the forums, abide by our community guidelines.
Quote:
Originally Posted by colorider View Post
Phobias are for irrational fears. Fear of junk ripping badgers is perfectly rational. Those things are nasty.
jsharr is offline   Reply With Quote
Old 07-31-05, 10:11 PM   #6
Post42K
Senior Member
Thread Starter
 
Join Date: Jul 2003
Location: Northern VA
Bikes:
Posts: 185
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by jsharr
Try giving the ring a turn or two if possible, to increase sealing pressure of the pump head onto the stem.
I tried that but no luck....it was already as tight as it would go.
Post42K is offline   Reply With Quote
Old 07-31-05, 11:01 PM   #7
531Aussie
Aluminium Crusader :-)
 
Join Date: Apr 2004
Location: Melbourne, Australia
Bikes:
Posts: 9,991
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
this is why a buy tubes with threaded stems

Vredestein Race tubes are great

Last edited by 531Aussie; 08-01-05 at 09:24 AM.
531Aussie is offline   Reply With Quote
Old 08-01-05, 08:05 AM   #8
jsharr
You Know!? For Kids!
 
jsharr's Avatar
 
Join Date: Apr 2005
Location: Just NW of Richardson Bike Mart
Bikes: '05 Trek 1200 / '90 Trek 8000 / '? Falcon Europa
Posts: 6,157
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 3 Post(s)
What if you took a bit of sand paper to the non threaded metal portion of the stem to roughen it up and give the pump head a bit more grip. Also, might give pump head and stem a good cleaning, maybe grease on either part is allowing head to pop off.
__________________
Are you a registered member? Why not? Click here to register. It's free and only takes 27 seconds! Help out the forums, abide by our community guidelines.
Quote:
Originally Posted by colorider View Post
Phobias are for irrational fears. Fear of junk ripping badgers is perfectly rational. Those things are nasty.
jsharr is offline   Reply With Quote
Old 08-01-05, 10:08 AM   #9
roadfix
hello
 
roadfix's Avatar
 
Join Date: May 2003
Location: Los Angeles
Bikes:
Posts: 18,568
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 11 Post(s)
...or you can do this for the time being.....
roadfix is offline   Reply With Quote
Old 08-01-05, 10:12 AM   #10
caloso
Packfodding 3
 
caloso's Avatar
 
Join Date: Jul 2002
Location: Sacramento, California, USA
Bikes: Ridley Excalibur, Gazelle Champion Mondial, On-One Pompino, Specialized Rock Hopper
Posts: 33,752
Mentioned: 4 Post(s)
Tagged: 0 Thread(s)
Quoted: 112 Post(s)
It's a PITA, isn't it?

I have a similar problem with my TopDog pump. My path-of-least-resistance solution is to buy threaded stem tubes whenever possible.
caloso is online now   Reply With Quote
Old 08-01-05, 10:16 AM   #11
531Aussie
Aluminium Crusader :-)
 
Join Date: Apr 2004
Location: Melbourne, Australia
Bikes:
Posts: 9,991
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by The Fixer
...or you can do this for the time being.....
jee, you've even got matching brown thingies on your brake adjuster doovies
531Aussie is offline   Reply With Quote
Old 08-01-05, 10:17 AM   #12
roadfix
hello
 
roadfix's Avatar
 
Join Date: May 2003
Location: Los Angeles
Bikes:
Posts: 18,568
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 11 Post(s)
Quote:
Originally Posted by caloso
It's a PITA, isn't it?

I have a similar problem with my TopDog pump. My path-of-least-resistance solution is to buy threaded stem tubes whenever possible.
Just the pump head is the Pista, which can be purchased separately and attached to any pump. Rubber ring on mine is a bit worn (actually from using this type of pump head on THREADED valve stems). With a new ring, it'll slide onto threadless valve stems without slipping back out.
roadfix is offline   Reply With Quote
Old 08-01-05, 01:51 PM   #13
Post42K
Senior Member
Thread Starter
 
Join Date: Jul 2003
Location: Northern VA
Bikes:
Posts: 185
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Yes, definitely a PITA (Fixer - I think he meant Pain in the A**). Good to know I'm not the only one with the problem. I'll try sanding/cleaning as jsharr suggested but I think it's back to threaded stems for me. Thanks for the input!
Post42K is offline   Reply With Quote
Old 08-01-05, 03:16 PM   #14
caloso
Packfodding 3
 
caloso's Avatar
 
Join Date: Jul 2002
Location: Sacramento, California, USA
Bikes: Ridley Excalibur, Gazelle Champion Mondial, On-One Pompino, Specialized Rock Hopper
Posts: 33,752
Mentioned: 4 Post(s)
Tagged: 0 Thread(s)
Quoted: 112 Post(s)
Sorry for the confusion. Yes, I meant pain in the a**. An acronym I picked from my Dad.

I've tried wrapping a little electrical tape around the valve stem, and that works a little but not much.
caloso is online now   Reply With Quote
Old 08-01-05, 04:29 PM   #15
Habu2112
Go Like Hell
 
Habu2112's Avatar
 
Join Date: Mar 2005
Location: Wichita, KS
Bikes: Merckx, S-Works, Voodoo
Posts: 87
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Always buy threaded stems, it's just not worth the trouble you are having. Conti makes good long stem, threaded tubes.
Habu2112 is offline   Reply With Quote
Old 08-01-05, 04:41 PM   #16
khuon
DEADBEEF
 
khuon's Avatar
 
Join Date: Aug 2002
Location: Catching his breath alongside a road near Seattle, WA USA
Bikes: 1999 K2 OzM, 2001 Aegis Aro Svelte
Posts: 12,242
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
I've never had a problem with threadless stems and my Topeak Twister pump. Note that the Joe Blow Sport uses the TwinHead pump head whereas the midrange and higher end Topeak pumps use the SmartHead. It could be that the cheaper pump heads don't hold unthreaded stems as well. If you want to continue using unthreaded stems then you might want to consider upgrading the pump head to a SmartHead. I personally prefer unthreaded stems since they don't chew up my seals and actually a good pump head and an unthreaded stem is probably going to provide a better seal than with a threaded stem. Also, I know this might seem like a dumb question, but are you certain you were using the correct end (presta) of the TwinHead and did you make sure to turn the valve lock the correct way?
__________________
1999 K2 OzM 2001 Aegis Aro Svelte
"Be liberal in what you accept, and conservative in what you send." -- Jon Postel, RFC1122
khuon is offline   Reply With Quote
Old 08-01-05, 05:52 PM   #17
Post42K
Senior Member
Thread Starter
 
Join Date: Jul 2003
Location: Northern VA
Bikes:
Posts: 185
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
I just double-checked and am definitely using the presta side of the pump and locking it in the right direction. I also tried sanding/cleaning and even the electrical tape but no luck. I did come up with an interim solution. I attached a presta/schrader adapter to the threadless valve so I could use the schrader side of the twinhead pump. Works like a charm! It's a few extra steps but at least it'll get the job done until I'm ready to change the tube. My luck this tube will last forever
Post42K is offline   Reply With Quote
Old 08-02-05, 05:43 AM   #18
infieldfly
Junior Member
 
Join Date: Dec 2004
Bikes:
Posts: 15
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Buy 99 cent adapter from presta to schrader. Although I think roughing or cleaning surface of stem will help.
infieldfly is offline   Reply With Quote
Old 08-02-05, 03:39 PM   #19
khuon
DEADBEEF
 
khuon's Avatar
 
Join Date: Aug 2002
Location: Catching his breath alongside a road near Seattle, WA USA
Bikes: 1999 K2 OzM, 2001 Aegis Aro Svelte
Posts: 12,242
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by Post42K
I just double-checked and am definitely using the presta side of the pump and locking it in the right direction. I also tried sanding/cleaning and even the electrical tape but no luck. I did come up with an interim solution.
Sounds like the presta side of the head is shot. I use unthreaded valved Michelin tubes with my Topeak SmartHead and have never had a problem. I regularly pump to 130PSI.
__________________
1999 K2 OzM 2001 Aegis Aro Svelte
"Be liberal in what you accept, and conservative in what you send." -- Jon Postel, RFC1122
khuon 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 11:22 PM.