Inner tubes

yost72

I’ve just bought some GP 5000 tyres but went for 28mm, whereas I previously had 25mm Gatorskins. I just realised that all of my spare inner tubes are 18-25mm. I assume I’m going to have to buy new inner tubes before I fit the new tyres, or would I get away with using those I already have?

DeVlaeminck

I'd use them as there's not a lot in it - they may stretch a little thinner but then you get lighter and heavier weight tubes anyway which presumably are different thicknesses.

N0bodyOfTheGoat

Those 25mm Gatorskins probably measured more like 26mm in the real world, while the 28mm GP5000 will measure ~29mm.

The old tubes will probably be fine, slightly more risk on the rear that takes more weight, if you've never tried them before maybe have a look for some latex tubes.

First.Aspect

Really don't try latex tubes. They are extremely fragile and far more permeable than butyl tubes. They are another one of the old school roadie performance gain things that the pragmatic only try once.

Just use your tubes. They will be fine. I had to use a 26" tube in a 29er wheel once in an emergency.

DeVlaeminck

They are worth a few watts for the sake of pumping your tyres up every couple of rides, they aren't fragile other than they are easier to pinch when you fit them - however if you are using gatorskins probably not much point in going for a more supple inner tube.

MattFalle

your existing tubes will be fine.

install. inflate. injoy.

First.Aspect

DeVlaeminck said:

They are worth a few watts for the sake of pumping your tyres up every couple of rides, they aren't fragile other than they are easier to pinch when you fit them - however if you are using gatorskins probably not much point in going for a more supple inner tube.

You almost make it sound like they are fragile and leaky, for a minimal benefit?

I'd almost be tempted by trying one of the polyurethane ones.

pblakeney

First.Aspect said:

Really don't try latex tubes. They are extremely fragile and far more permeable than butyl tubes. They are another one of the old school roadie performance gain things that the pragmatic only try once.

Just use your tubes. They will be fine. I had to use a 26" tube in a 29er wheel once in an emergency.

Consider me one of those.
Not worth the expense far less the hassle, even if minimal, as the benefits are even less.

Charlie_Croker

Your old tubes will be fine, go with them until it’s time to replace them

One word of caution (from experience) after you’ve mended a puncture resist the temptation to fully inflate the tyre for 24 hours, let the rubber solution fully cure first

MattFalle

Charlie_Croker said:

Your old tubes will be fine, go with them until it’s time to replace them

One word of caution (from experience) after you’ve mended a puncture resist the temptation to fully inflate the tyre for 24 hours, let the rubber solution fully cure first

yes, this.

for some paraoud reason i also stick a weight on top of the patch while the glue sets. probably goes absolutely nothing at all apart from assuage my paranoia.

DeVlaeminck

First.Aspect said:

DeVlaeminck said:

They are worth a few watts for the sake of pumping your tyres up every couple of rides, they aren't fragile other than they are easier to pinch when you fit them - however if you are using gatorskins probably not much point in going for a more supple inner tube.

You almost make it sound like they are fragile and leaky, for a minimal benefit?

I'd almost be tempted by trying one of the polyurethane ones.

It's several watts for the sake of pumping your tyres up every few days - in terms of marginal gains that seems worth it to me but ymmv. It's a bit like buying a top end race tyre or a cheaper one or maybe a more puncture resistant model - performance gains aren't life changing but they are real.

They aren't fragile - they don't puncture more easily than butyl - they are a bit easier to trap between the rim and the tyre when fitting them but so long as you know that and make sure they aren't pinched before inflating it's not an issue.

DeVlaeminck

Re. Puncture repairs - if I'm out on my own I often patch tubes, wait about 60 seconds then good to go - so my experience is you don't have to wait 24 hours.

As we are on the subject you can patch latex tubes too.

First.Aspect

I just looked it up. At 45 kph the benefit of latex tubes is about 3W. So rather less at 30 kph. If it goes by the square of speed that's less than 1.5W.

The PU tubes aren't far behind latex and I'm assuming tubeless are now better that all of them.

DeVlaeminck

This suggests you are underselling the advantage.

https://www.aero-coach.co.uk/inner-tube-rolling-resistance

Not sure why a PU tube is considered better when it costs more and is slower than latex.

As I say it's a small advantage - about 5 watts at race speeds - but for a few pounds extra and the bother of having to top up your tyres before a ride for me it's worth it.

5 watts for less than a tenner - I'd suggest if they sold a jersey that gave you 50 watts for £100 nobody would race in anything else so to me it seems odd not to use latex tubes if you are interested in going faster.

It's individual choice but they certainly aren't some outdated old school tech lots of people use them on their best bikes. And before someone says they explode if the overheat maybe if you can't descend very well they do I don't know - I've used them in the Alps plenty before I'd ever heard this claim and never had a blowout.

First.Aspect

Same data.

The pu tubes are supposed to be more puncture resistant. Allegedly.

Do you think 7w would be saved to overall rolling resistance in the real world?

If you added up all the supposed power savings for all of the bits of tech that save power, bikes would be spontaneously self propelling by now. So it's not additive, is it.

Either way, for the PITA of latex tubes and cost, they aren't for me personally. Same reason I've steered clear of tubeless so far.

MattFalle

Can't fault a good tubular, tbh....

orraloon

Just go tubeless. Move into the 21st century. 😉

DeVlaeminck

First.Aspect said:

Same data.

The pu tubes are supposed to be more puncture resistant. Allegedly.

Do you think 7w would be saved to overall rolling resistance in the real world?

If you added up all the supposed power savings for all of the bits of tech that save power, bikes would be spontaneously self propelling by now. So it's not additive, is it.

Either way, for the PITA of latex tubes and cost, they aren't for me personally. Same reason I've steered clear of tubeless so far.

The PITA is literally a couple of strokes on a track pump !

As for real world - I think gains in rolling resistance are probably more reliable than aerodynamics. I mean you can race on a set of Gatorskins which would be the same logic as not using latex tubes.