Go Back  Bike Forums > Bike Forums > Road Cycling
Reload this Page >

2 Weeks off Bike - Rear Tire Pressure Way Down

Notices
Road Cycling “It is by riding a bicycle that you learn the contours of a country best, since you have to sweat up the hills and coast down them. Thus you remember them as they actually are, while in a motor car only a high hill impresses you, and you have no such accurate remembrance of country you have driven through as you gain by riding a bicycle.” -- Ernest Hemingway

2 Weeks off Bike - Rear Tire Pressure Way Down

Old 07-28-19, 09:21 PM
  #1  
puma1552
Senior Member
Thread Starter
 
Join Date: Jul 2016
Posts: 740

Bikes: '17 Colnago C-RS (Full 5800); '16 Specialized Sirrus Elite

Mentioned: 4 Post(s)
Tagged: 0 Thread(s)
Quoted: 360 Post(s)
Liked 60 Times in 38 Posts
2 Weeks off Bike - Rear Tire Pressure Way Down

Recently swapped wheels/tires and am running 25mm GP 5000 clinchers, with Conti Race 28 butyl tubes in the smaller 18-25mm size. Not the Conti Race Light tubes, just the regular Race 28s.

I run my front at 80 psi, rear at 90 psi.

I noticed from the onset that the rear bleeds pressure quicker, can be 10 psi or close to it overnight the first night, and then drops off more slowly after that. Front drops maybe 5 psi the first night, and less after that.

I've been off the bike for 2 weeks, and thought just now to check the pressures. The front was at 60 psi (seems perfectly fine for that length of time), but the rear was down to just under 35 psi, which seems way low to me.

I understand tubes at higher pressures will drop quicker as air permeates out through the pore tubes, but is this normal? Or can I expect that I have the world's tiniest leak in the rear tube?
puma1552 is offline  
Old 07-28-19, 09:37 PM
  #2  
noodle soup
Senior Member
 
noodle soup's Avatar
 
Join Date: Nov 2015
Posts: 8,922
Mentioned: 20 Post(s)
Tagged: 0 Thread(s)
Quoted: 4717 Post(s)
Liked 1,882 Times in 998 Posts
If the valve cores are removable, I'd pull them out, and clean them.
noodle soup is offline  
Old 07-29-19, 09:10 PM
  #3  
puma1552
Senior Member
Thread Starter
 
Join Date: Jul 2016
Posts: 740

Bikes: '17 Colnago C-RS (Full 5800); '16 Specialized Sirrus Elite

Mentioned: 4 Post(s)
Tagged: 0 Thread(s)
Quoted: 360 Post(s)
Liked 60 Times in 38 Posts
Not sure if they are, but the tubes are new so should be nice and clean.
puma1552 is offline  
Old 07-29-19, 10:49 PM
  #4  
ThermionicScott 
working on my sandal tan
 
ThermionicScott's Avatar
 
Join Date: Aug 2011
Location: CID
Posts: 22,625

Bikes: 1991 Bianchi Eros, 1964 Armstrong, 1988 Diamondback Ascent, 1988 Bianchi Premio, 1987 Bianchi Sport SX, 1980s Raleigh mixte (hers), All-City Space Horse (hers)

Mentioned: 98 Post(s)
Tagged: 0 Thread(s)
Quoted: 3868 Post(s)
Liked 2,560 Times in 1,574 Posts
On occasion, valve cores aren't tightened enough in brand-new tubes. You might try tightening it a bit.

Even though the rear tire started at a higher pressure, it shouldn't lose air so fast as to beat the front tire to 35 psi. Might be good to check your rear tire for any tiny shards embedded in the tread that could be causing a very slow leak.
__________________
Originally Posted by chandltp
There's no such thing as too far.. just lack of time
Originally Posted by noglider
People in this forum are not typical.
RUSA #7498
ThermionicScott is offline  
Likes For ThermionicScott:
Old 07-29-19, 11:25 PM
  #5  
noodle soup
Senior Member
 
noodle soup's Avatar
 
Join Date: Nov 2015
Posts: 8,922
Mentioned: 20 Post(s)
Tagged: 0 Thread(s)
Quoted: 4717 Post(s)
Liked 1,882 Times in 998 Posts
Originally Posted by puma1552
Not sure if they are, but the tubes are new so should be nice and clean.
Yes, they should be perfectly clean, but that's not always the case.

Remove, clean, and install the valves again.

Eliminate possible problems, or just replace the tubes(after checking the tires for things that caused a puncture).
noodle soup is offline  
Old 07-30-19, 03:21 AM
  #6  
trailangel
Senior Member
 
trailangel's Avatar
 
Join Date: Feb 2014
Location: Pasadena, CA
Posts: 4,847

Bikes: Schwinn Varsity

Mentioned: 22 Post(s)
Tagged: 0 Thread(s)
Quoted: 1931 Post(s)
Liked 741 Times in 421 Posts
You have Conti tubes and you don't know if you have removable valve cores?
Of course you have removable valve cores. You have not prepped correctly. Check valve cores.... ..... .....
trailangel is offline  
Old 07-30-19, 08:40 AM
  #7  
puma1552
Senior Member
Thread Starter
 
Join Date: Jul 2016
Posts: 740

Bikes: '17 Colnago C-RS (Full 5800); '16 Specialized Sirrus Elite

Mentioned: 4 Post(s)
Tagged: 0 Thread(s)
Quoted: 360 Post(s)
Liked 60 Times in 38 Posts
Can I tighten the core without removing the wheel/tire/tube? Guessing the answer is no?
puma1552 is offline  
Old 07-30-19, 08:47 AM
  #8  
trailangel
Senior Member
 
trailangel's Avatar
 
Join Date: Feb 2014
Location: Pasadena, CA
Posts: 4,847

Bikes: Schwinn Varsity

Mentioned: 22 Post(s)
Tagged: 0 Thread(s)
Quoted: 1931 Post(s)
Liked 741 Times in 421 Posts
Answer is YES
trailangel is offline  
Old 07-30-19, 08:55 AM
  #9  
noodle soup
Senior Member
 
noodle soup's Avatar
 
Join Date: Nov 2015
Posts: 8,922
Mentioned: 20 Post(s)
Tagged: 0 Thread(s)
Quoted: 4717 Post(s)
Liked 1,882 Times in 998 Posts
Originally Posted by puma1552
Can I tighten the core without removing the wheel/tire/tube? Guessing the answer is no?
Yes.
noodle soup is offline  
Old 07-30-19, 09:18 AM
  #10  
WhyFi
Senior Member
 
WhyFi's Avatar
 
Join Date: Jan 2010
Location: TC, MN
Posts: 39,505

Bikes: R3 Disc, Haanjo

Mentioned: 353 Post(s)
Tagged: 1 Thread(s)
Quoted: 20791 Post(s)
Liked 9,436 Times in 4,663 Posts
Originally Posted by puma1552
Can I tighten the core without removing the wheel/tire/tube? Guessing the answer is no?
You see the opposing little flat spots on the smaller set of threads? Them's for removing/installing the removable core.

WhyFi is offline  
Old 07-30-19, 09:21 AM
  #11  
ThermionicScott 
working on my sandal tan
 
ThermionicScott's Avatar
 
Join Date: Aug 2011
Location: CID
Posts: 22,625

Bikes: 1991 Bianchi Eros, 1964 Armstrong, 1988 Diamondback Ascent, 1988 Bianchi Premio, 1987 Bianchi Sport SX, 1980s Raleigh mixte (hers), All-City Space Horse (hers)

Mentioned: 98 Post(s)
Tagged: 0 Thread(s)
Quoted: 3868 Post(s)
Liked 2,560 Times in 1,574 Posts
I use two pairs of needle-nose pliers and gently turn them together. The amount of movement you can get with a light touch is all it takes.
__________________
Originally Posted by chandltp
There's no such thing as too far.. just lack of time
Originally Posted by noglider
People in this forum are not typical.
RUSA #7498
ThermionicScott is offline  
Old 07-30-19, 10:35 AM
  #12  
popeye
Senior Member
 
Join Date: Nov 2004
Location: Newport Beach, CA
Posts: 1,935

Bikes: S works Tarmac, Felt TK2 track

Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 359 Post(s)
Liked 179 Times in 111 Posts
My last batch of Conti tubes all had loose cores.
popeye is offline  
Likes For popeye:
Old 07-31-19, 10:30 AM
  #13  
seedsbelize 
smelling the roses
 
seedsbelize's Avatar
 
Join Date: Nov 2010
Location: Tixkokob, Yucatán, México
Posts: 15,428

Bikes: 79 Trek 930, 80 Trek 414, 84 Schwinn Letour Luxe (coupled), 92 Schwinn Paramount PDG 5

Mentioned: 104 Post(s)
Tagged: 1 Thread(s)
Quoted: 7081 Post(s)
Liked 901 Times in 612 Posts
I got on a bike, yesterday, that I hadn't been on since April. The tires were in tip top pressure. I was puzzled for a moment, and then remembered that bike shares a wheel set with the bike which was active last week.
seedsbelize is offline  
Likes For seedsbelize:
Old 07-31-19, 08:29 PM
  #14  
puma1552
Senior Member
Thread Starter
 
Join Date: Jul 2016
Posts: 740

Bikes: '17 Colnago C-RS (Full 5800); '16 Specialized Sirrus Elite

Mentioned: 4 Post(s)
Tagged: 0 Thread(s)
Quoted: 360 Post(s)
Liked 60 Times in 38 Posts
Thanks guys, and thanks @WhyFi for that diagram...I checked both front and rear, and oddly enough I was able to tighten both of them about half a turn, so I did that and pumped the tires back up. Will see how that goes, guess I know now to always check that on new tubes.
puma1552 is offline  
Old 08-01-19, 04:38 AM
  #15  
Sy Reene
Advocatus Diaboli
 
Sy Reene's Avatar
 
Join Date: Feb 2015
Location: Wherever I am
Posts: 8,613

Bikes: Merlin Cyrene, Nashbar steel CX

Mentioned: 14 Post(s)
Tagged: 1 Thread(s)
Quoted: 4717 Post(s)
Liked 1,526 Times in 997 Posts
Originally Posted by puma1552
Thanks guys, and thanks @WhyFi for that diagram...I checked both front and rear, and oddly enough I was able to tighten both of them about half a turn, so I did that and pumped the tires back up. Will see how that goes, guess I know now to always check that on new tubes.
Yeah.. it's especially fun to find they're not tightened enough when roadside, after fixing a flat, and you have a screw-on pump head -- then when removing takes the core out at the same time.
Sy Reene is offline  
Old 08-01-19, 06:34 AM
  #16  
WhyFi
Senior Member
 
WhyFi's Avatar
 
Join Date: Jan 2010
Location: TC, MN
Posts: 39,505

Bikes: R3 Disc, Haanjo

Mentioned: 353 Post(s)
Tagged: 1 Thread(s)
Quoted: 20791 Post(s)
Liked 9,436 Times in 4,663 Posts
Originally Posted by Sy Reene
Yeah.. it's especially fun to find they're not tightened enough when roadside, after fixing a flat, and you have a screw-on pump head -- then when removing takes the core out at the same time.
That's such a kick in the nuts when it happens.
WhyFi is offline  
Old 08-06-19, 08:38 PM
  #17  
puma1552
Senior Member
Thread Starter
 
Join Date: Jul 2016
Posts: 740

Bikes: '17 Colnago C-RS (Full 5800); '16 Specialized Sirrus Elite

Mentioned: 4 Post(s)
Tagged: 0 Thread(s)
Quoted: 360 Post(s)
Liked 60 Times in 38 Posts
Sees to have done the trick. After tightening the cores, pumped the rear back to 90 on Sunday morning and now, Tuesday night, it was sitting at 80, so that seems just right. Much better than before, glad I don't have to deal with swapping a tube.
puma1552 is offline  
Old 08-06-19, 08:46 PM
  #18  
trailangel
Senior Member
 
trailangel's Avatar
 
Join Date: Feb 2014
Location: Pasadena, CA
Posts: 4,847

Bikes: Schwinn Varsity

Mentioned: 22 Post(s)
Tagged: 0 Thread(s)
Quoted: 1931 Post(s)
Liked 741 Times in 421 Posts
Originally Posted by puma1552
Sees to have done the trick. After tightening the cores, pumped the rear back to 90 on Sunday morning and now, Tuesday night, it was sitting at 80, so that seems just right. Much better than before, glad I don't have to deal with swapping a tube.
Good deal, but now that you have mentioned not changing the tube... a flat tire is around the corner.
trailangel is offline  
Likes For trailangel:
Old 08-10-19, 07:18 PM
  #19  
puma1552
Senior Member
Thread Starter
 
Join Date: Jul 2016
Posts: 740

Bikes: '17 Colnago C-RS (Full 5800); '16 Specialized Sirrus Elite

Mentioned: 4 Post(s)
Tagged: 0 Thread(s)
Quoted: 360 Post(s)
Liked 60 Times in 38 Posts
Originally Posted by trailangel
Good deal, but now that you have mentioned not changing the tube... a flat tire is around the corner.
So far I've made it all three seasons since I started cycling without a single one...my luck is surely about to run out, and it surely will be the rear, and it surely will happen when I'm at the turn around point, furthest from my car, and in an area with no shade.
puma1552 is offline  
Old 08-11-19, 04:22 PM
  #20  
Wileyrat
Senior Member
 
Join Date: Mar 2013
Location: Tucson Az
Posts: 1,655

Bikes: 2015 Ridley Fenix, 1983 Team Fuji, 2019 Marin Nail Trail 6

Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 332 Post(s)
Liked 205 Times in 128 Posts
Originally Posted by puma1552
So far I've made it all three seasons since I started cycling without a single one...my luck is surely about to run out, and it surely will be the rear, and it surely will happen when I'm at the turn around point, furthest from my car, and in an area with no shade.
Guaranteed to happen now. You've angered the flat gnomes by bragging about not getting a flat.

If I were you, I'd start carrying two spare tubes and a patch kit.

Last edited by Wileyrat; 08-11-19 at 04:32 PM.
Wileyrat is offline  
Old 08-11-19, 07:14 PM
  #21  
big john
Senior Member
 
big john's Avatar
 
Join Date: Sep 2005
Location: In the foothills of Los Angeles County
Posts: 25,107
Mentioned: 8 Post(s)
Tagged: 0 Thread(s)
Quoted: 8191 Post(s)
Liked 8,851 Times in 4,396 Posts
Originally Posted by puma1552
So far I've made it all three seasons since I started cycling without a single one...my luck is surely about to run out, and it surely will be the rear, and it surely will happen when I'm at the turn around point, furthest from my car, and in an area with no shade.
You've never had a flat while riding? Practice changing a tube at home, should only take a few minutes.

If you have doubts about a tube you can submerge it in water and look for bubbles.
big john is offline  
Old 08-12-19, 01:27 PM
  #22  
Abe_Froman
Senior Member
 
Abe_Froman's Avatar
 
Join Date: Aug 2016
Location: Chicago
Posts: 2,566

Bikes: Marin Four Corners, 1960's Schwinn Racer in middle of restoration, mid 70s Motobecane Grand Touring, various other heaps.

Mentioned: 76 Post(s)
Tagged: 0 Thread(s)
Quoted: 9347 Post(s)
Liked 57 Times in 51 Posts
Originally Posted by Sy Reene
Yeah.. it's especially fun to find they're not tightened enough when roadside, after fixing a flat, and you have a screw-on pump head -- then when removing takes the core out at the same time.
I've done that TWICE with the CO2 screw on inflator
Abe_Froman is offline  
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
RoscoeP
Mountain Biking
8
06-07-18 07:51 PM
alfordjo
Road Cycling
29
09-01-17 06:14 AM
illusiumd
Commuting
15
12-08-16 01:49 PM
rgpg_99
Bicycle Mechanics
53
04-01-13 02:31 PM
notwist
Cyclocross and Gravelbiking (Recreational)
13
10-22-12 11:31 AM

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


Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service -

Copyright © 2024 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.