2 Weeks off Bike - Rear Tire Pressure Way Down
#1
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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?
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?
#3
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Not sure if they are, but the tubes are new so should be nice and clean.
#4
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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.
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.
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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).
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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.... ..... .....
Of course you have removable valve cores. You have not prepped correctly. Check valve cores.... ..... .....
#7
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Can I tighten the core without removing the wheel/tire/tube? Guessing the answer is no?
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#11
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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.
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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.
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#14
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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.
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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.
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#17
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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.
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#19
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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.
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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.
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If you have doubts about a tube you can submerge it in water and look for bubbles.
#22
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