problems with presta ineer tubes
moggy12
Posts: 109
i have a trek 7.5 fx hybrid bike fanastic bike used for getting fit but the problem is it has 700c x35 bontrager tyres with presta innertubes i pump up tubes to about 80psi 2 days later they are both down to 40psi checked for any puntures which there is'nt any i 'm still about 16 stone so when riding can this loose pressure in tyres ? i thought of replacing tubes with scrader ones will these fit in a 700c wheel ? thanks
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Wow - that's a big loss - Tried pumping them to max and dunking them in a bucket of water/soapy water to check for leaks? / removing the tubes and checking them in said bucket (albeit with light pressure)?
My MTB tyres with car valves hardly ever need pumping up - maybe a couple of times a month, and the Prestas on the road bike, maybe once a week due to a max. loss of 10 psi (c.100 to 90).
I'm using Specialized tubes - Pure latex tubes apparently leak a bit more.
Might be worth fitting a different branded inner, and seeing if that makes a difference - Just use the old one as a spare.0 -
"I'm using Specialized tubes - Pure latex tubes apparently leak a bit more"
Latex do leak but have an advantage in feel and weight - its not liklely that you would find latex tubes on a hybrid bike, or any beginner bike for that matter.0 -
They aren't latex tubes are they? My recollection of using them (a long time ago) is that they lose air a lot quicker. Needed daily replenishment.
Only have experience of 700x20c (at 100psi+) and 559x2.1 MTB tyres with Presta, and haven't had any problems with leakage (I use Continental mostly).
Schrader may not fit road 700c wheels, although they do fit my MTB ones with an adapter for presta.0 -
I have Presta valves on two out of three bikes and they don't lose pressure anywhere near that fast - I probably check them once a fortnight or so running 100/110psi.moggy12 wrote:i have a trek 7.5 fx hybrid bike fanastic bike used for getting fit but the problem is it has 700c x35 bontrager tyres with presta innertubes i pump up tubes to about 80psi 2 days later they are both down to 40psi checked for any puntures which there is'nt any i 'm still about 16 stone so when riding can this loose pressure in tyres ?
Just to check, you are screwing down the little screwy thing* that holds the valve shut? Assuming you are, then you either have two punctures, two dodgy valves or one of each. How are you checking for punctures? A slow puncture can be very hard to find, even using a bowl of water.
If your wheel was designed for Presta, that's what you're stuck with I'm afraid.moggy12 wrote:i thought of replacing tubes with scrader ones will these fit in a 700c wheel ? thanks
*Techincal terminology.Even if the voices aren't real, they have some very good ideas.0 -
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Eep! :shock:redddraggon wrote:moggy12 wrote:i thought of replacing tubes with scrader ones will these fit in a 700c wheel ?
Yeh, they'll work, you just need to drill the valve hole a bit bigger.
You sure that's a good idea? I know you can get adaptors to go from Schraeder to Presta, but I would have thought drilling the valve hole risks weakening the rim if it wasn't designed for that size of hole?
Seems a bit of a risk to take when there's nothing fundamentally wrong with Presta.Even if the voices aren't real, they have some very good ideas.0 -
Shadowduck wrote:
Eep! :shock:redddraggon wrote:moggy12 wrote:i thought of replacing tubes with scrader ones will these fit in a 700c wheel ?
Yeh, they'll work, you just need to drill the valve hole a bit bigger.
You sure that's a good idea? I know you can get adaptors to go from Schraeder to Presta, but I would have thought drilling the valve hole risks weakening the rim if it wasn't designed for that size of hole?
Seems a bit of a risk to take when there's nothing fundamentally wrong with Presta.
It wouldn't weaken the wheel that much, after all it's only a minuscule difference, as long as the hole is drilled in the correct place at the correct size.
Personally I wouldn't bother, but if he doesn't want to use proper road tubes, that's his only way.0 -
thanks for the info guys i use bontrager innertubes the ones what came with the bike i still don't think they have a puncture has when they get to 40psi they do'nt go any flatter i think i will change them for the specialized tubes and keep the bontrager as spares where is the best place to get some tubes ?0
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Silly point, but have you made sure the valve is closed properly and not left undone a bit after pumping up?
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Please use the proper terminology for things or we'll all get confused. It's correctly known as the...oldwelshman wrote:Silly point, but have you made sure the valve is closed properly and not left undone a bit after pumping up?Shadowduck wrote:*snip* ... little screwy thing that holds the valve shut ... *snip*
Even if the voices aren't real, they have some very good ideas.0 -
Shadowduck wrote:
Please use the proper terminology for things or we'll all get confused. It's correctly known as the...oldwelshman wrote:Silly point, but have you made sure the valve is closed properly and not left undone a bit after pumping up?Shadowduck wrote:*snip* ... little screwy thing that holds the valve shut ... *snip*
Well I am Wlesh, probably got lost in the translation 8)0 -
Shadowduck wrote:
Please use the proper terminology for things or we'll all get confused. It's correctly known as the...oldwelshman wrote:Silly point, but have you made sure the valve is closed properly and not left undone a bit after pumping up?Shadowduck wrote:*snip* ... little screwy thing that holds the valve shut ... *snip*
Well I am Wlesh, probably got lost in the translation 8)0
