Inner Tubes

[Mr.T]

First, I'm new here and also Thanks in advance for reading and helping me out.
I'm a casual bike rider who lives in a large city and enjoys getting out for a ride in the summer to enjoy the beautiful weather. I don't have a very fancy bike (Trek) but it get's me around just fine.
My Problem: I don't know if this is normal on all bike's but I have to put air in my tires every 2 weeks. I've replaced the inner tubes hoping I wouldn't have to keep adding air but it's just the same as before.
Question: Is this normal, or a slow leak and are there any inner tubes that are of better quality?
My Tires: Bontrager Nebula H5 700 x 35
Thanks to those who can help me out

[Jesper]

(05-06-2022, 11:29 AM)Mr.T Wrote:  First, I'm new here and also Thanks in advance for reading and helping me out.
I'm a casual bike rider who lives in a large city and enjoys getting out for a ride in the summer to enjoy the beautiful weather. I don't have a very fancy bike (Trek) but it get's me around just fine.
My Problem: I don't know if this is normal on all bike's but I have to put air in my tires every 2 weeks. I've replaced the inner tubes hoping I wouldn't have to keep adding air but it's just the same as before.
Question: Is this normal, or a slow leak and are there any inner tubes that are of better quality?
My Tires: Bontrager Nebula H5 700 x 35
Thanks to those who can help me out

Welcome Mr. T!

Have you checked to see where the tubes are leaking from (i.e. in the valve itself, near valve/main tube conjunction, outer area where tire contact is, inner area where rim contact is, sides-possibly pinched when installed)? If you've checked for leaks, are they always in the same spot? Always mark the tube, tire, and rim in relation to one another so you can inspect the all three in the same area where the tube leak is before completely removing the tube from the tire/rim. Ensure you have rim tape properly installed that is in good condition, and I would highly advise against using the cloth tape for higher pressure tires; use the stiffer plastic rim tape (I have to buy it online since many bike shops do not carry it. Higher pressure (100 psi plus) tires seem to need more regular reinflation on my bikes than mid (70-90 psi) to lower (below 70 psi) pressure tires. You can't properly check tubes used in higher pressure tires for micro leaks because pumping them up free from the tire causes them to stretch (or explode), and thus not fit correctly when reinstalled. I usually pump up the loose tube enough for it to be fully shaped and maybe add another pump or 2 to give it ample pressure to find the more inconspicuous leaks.
If at home submerge it in a bucket of water with a little dish detergent in it. Also, check the interior of your tire and rim for any foreign material or damage by sight and by feel (again, if you marked the tube and tire if should be easy to find if the tire has something in it causing the tube puncture). There are some heavier duty tubes meant to be a little more resistant to punctures, as well as light weight tubes. I just use whatever is available at the store and have had about the same results in general with them all (that does not apply to the tires though). I have never used the "Slime" brand tubes which have their proprietary goop inside that helps seal a tube if it gets punctured. I don't know anyone who has used them since they don't (to my knowledge) produce them in the size that fits the narrower tires that my friends and myself ride. They are also much heavier because of the additive.
You can of course buy puncture resistant tires, and/or add an anti-puncture strip (old school style; not sure if it is still made) between the tire and tube.
I also add a small thin rubber washer made from old tubes at the valve stem to avoid possible damage to the tube at the rim penetration point. Just cut a small bit with a small hole to fit the valve stem through, but small enough that you need to stretch it slightly to pull down the stem towards the tube. This is something that can help protect your tube if it shifts slightly or if the rim hole is somewhat sharp (sand or deburr it somehow if possible).

[ReapThaWhirlwind]

This is pretty normal imo. When you hit bumps it can knock some air out of the tires.

Presta valves are supposed to improve upon this, but not absolutely I'm afraid.

You can run Presta valve tubes in Schrader valve holes with an adapter.

https://www.brandscycle.com/product/sunlite-rim-grommet-324698-1.htm

[Criminal]

Increased pressure "knocks" air out of tubes; whether from riding (more weight on tires), or from warming of the wheels (ambient temperature and friction from riding). I doubt your repetitive problem is the result of "bumps". Do you lose pressire when the bike is not being used over the 2 week period, or is it during regular daily use? Are you using the correct tube size? Try to get a tube closer to your tire size since using a tube that fits a range of tire sizes can cause increased stretching of the tube when used on a tire where the tube is designed to fit your tire, but is doing so at the smaller side of the range on a tire at the larger size of the range. Example: tire size is 700c x 28mm, and tube fits tires 23mm to 28mm. In a 23mm tire there is less stretch than if using in a 28mm tire. Try to get a tube that fits 28mm to 32mm tires instead if possible. Sometimes you can get the better fitting tube and it will not have to stretch as much when inflated to fit your tire. That is not always possible and it depends on each manufacturer's designed sizes. The higher the rated tire pressure, the more important it becomes to have a tube size closer to the actual tire size.