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Singlespeed & Fixed Gear "I still feel that variable gears are only for people over forty-five. Isn't it better to triumph by the strength of your muscles than by the artifice of a derailer? We are getting soft...As for me, give me a fixed gear!"-- Henri Desgrange (31 January 1865 - 16 August 1940)

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Old 01-19-11, 01:52 AM   #1
FixedAgenda
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Question About Slow Leaks

I'm fairly new to the cycling community and need a little help from you more experienced cyclists. When I first bought my bike, I noticed after the first couple of days that both front and back tubes had really slow leaks. For the first few months, I thought it was just from the everyday riding that was causing the loss of air. But after a 2 months, I decided to just try adding a little slime to both tubes. This worked perfectly and I never had to put air in the tires again.

A few months after sliming the tubes, I bought new rims which came with new tires and tubes. After airing them up to the recommended p.s.i., I noticed a slow leak in the rear tire. This is the second set of new tires and tubes that I've had with a slow leak from the very time I've started riding on them.

Is this normal? I would just slime the new tubes but they have presta valves where as my original tubes had schrader valves. I haven't found a way to slime a presta valve without removing the stem. That's not something I want to do.

I have several questions.

Is it normal to experience slow leaks in new tubes and tires?

What is the best way to fix this issue when you have presta valves?

Can my local bike shop slime my tubes for me?

Thanks in advance for your help fellas?
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Old 01-19-11, 02:02 AM   #2
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the easiest way to slime the tube with a presta valve is buy a presta-schraeder adapter (usually under $1us on fleabay) and then do it as normal... you can even leave the adapters on your valves to make it easier to fill your tubes in an emergency at a service station

just make sure you get metal adapters as i have had the plastic ones break on me
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Old 01-19-11, 02:05 AM   #3
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1) Yes. Thin rubber is slightly permeable to air molecules so they will gradually lose pressure. There's nothing wrong with the tubes.
2) Best is to just pump them up regularly. You can get heavy-duty tubes made of thicker rubber but they'll be heavier and also (separately) have greater rolling resistance due to the hysteresis losses from flexing the thicker tube as the wheel rotates. Adding Slime is an even heavier way of reducing the rate of air loss. There are Presta valves that are removable to let you add the Slime. The other method is to cut a hole in the tube, add the Slime, and then patch the hole.
3) Best to ask them instead of us.
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Old 01-19-11, 02:13 AM   #4
FixedAgenda
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Quote:
Originally Posted by NikZak View Post
the easiest way to slime the tube with a presta valve is buy a presta-schraeder adapter (usually under $1us on fleabay) and then do it as normal... you can even leave the adapters on your valves to make it easier to fill your tubes in an emergency at a service station

just make sure you get metal adapters as i have had the plastic ones break on me
Thanks for your reply. I actually have the adapters but I didn't think it was possible to slime through the adapter. I'll consider giving it a try. Thanks again.


Quote:
Originally Posted by prathmann View Post
1) Yes. Thin rubber is slightly permeable to air molecules so they will gradually lose pressure. There's nothing wrong with the tubes.
2) Best is to just pump them up regularly. You can get heavy-duty tubes made of thicker rubber but they'll be heavier and also (separately) have greater rolling resistance due to the hysteresis losses from flexing the thicker tube as the wheel rotates. Adding Slime is an even heavier way of reducing the rate of air loss. There are Presta valves that are removable to let you add the Slime. The other method is to cut a hole in the tube, add the Slime, and then patch the hole.
3) Best to ask them instead of us.
Tons of great info there sir. Thanks so much. I'm not too concerned with the added weight and rolling resistance. I'm just a leisure biker and sometimes wear up to a 20lb backpack. I will talk to my local bike shop about my options and consider yours as well. Thanks again for your advice.
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Old 01-19-11, 02:48 AM   #5
Leukybear
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Alternatively you can just buy a tube that allows you to extend the valve length for those super deep aero rims. For those, the presta valve is removable and you can squeeze in the slime and replace it; as opposed to intentionally puncturing the tube and resealing it afterward.
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Old 01-19-11, 03:15 AM   #6
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More people have responded to the "jordans" thread than this one. Just an observation
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Old 01-19-11, 05:24 AM   #7
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Just how slow a leak are you talking about? It is normal for high pressure road tire/tubes to lose a couple of PSI a day.
The usual response is to get a good floor pump and top up your tires before riding. With a good floor pump that will only take a minute for both tires.
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