Latex tubes losing pressure - what would they lose over 6 hours riding?

daniel_b

Morning all,

I am taking part in Ride London, and am hoping it will take me around 6 hours.

I currently have my road bike with normal tubes, and will have new tyres on for the event, or an aero bike with 2 ride old tyres on, and latex tubes.

I am aware how much more quickly latex tubes lose pressure simply when the bike is hung up, so am wondering if the rate of loss is more when being ridden, and if they might be low to the point where they are looking to pinch puncture at the tail end of the ride.

I run 25mm tyres, and as am not too heavy, tend to go out with 90 in the rear, and 80 in the front.

Would another method be to start with 110\100 to counteract some of the pressure loss?

joe_totale-2

In my experience with Michelin latex tubes they may lose 5-10 psi over the ride, nothing too dramatic.
6 hours seems quite a conservative time to me for Ride London given it's pretty flat, the closed roads certainly speed you up.

N0bodyOfTheGoat

Daniel B wrote:

Morning all,

I am taking part in Ride London, and am hoping it will take me around 6 hours.

I currently have my road bike with normal tubes, and will have new tyres on for the event, or an aero bike with 2 ride old tyres on, and latex tubes.

I am aware how much more quickly latex tubes lose pressure simply when the bike is hung up, so am wondering if the rate of loss is more when being ridden, and if they might be low to the point where they are looking to pinch puncture at the tail end of the ride.

I run 25mm tyres, and as am not too heavy, tend to go out with 90 in the rear, and 80 in the front.

Would another method be to start with 110\100 to counteract some of the pressure loss?

Given you are much lighter than me (I'm ~81Kg and you're something like ~65Kg IIRC), you shouldn't need pressures anywhere near what I use. At the mo I would normally head off with ~90/100PSI front/rear with butyl tubes and a total weight of ~95Kg for me kitted out for a ride with ~1.5l water and food/kit/mobile etc. in my jersey pockets.

If your tyres run true to size and their real world width matches the specs of your latex tubes, I'd expect them to lose less pressure over a ride duration of ~6 hours.

If you can't fit in a ride beforehand of 2-3 hours with the latex tubes and tyres, to monitor real world pressure loss (which I expect to be a slightly higher rate of loss at higher pressures), you could always install them to a known pressure and see what happens over several hours of the bike being at home.

The only outdoor ride I've done so far since fitting the "28mm" GP4000s and latex tubes recently was a quick blast for 40mins on the local inclines last Saturday evening, but I do have vague recollections of topping up my latex tubes while out on rides of 3+ hours last summer... Especially the weight-bearing rear tube/wheel, after a few hours it would start to feel too squishy for my liking.

Matthewfalle

if you're that worried why just not pop some butyl ones in? one less thing to worry about.

#withoutaworry

pblakeney

Last time I used latex tubes (and it will be the last) was in Mallorca with them starting off at 100psi.
Next morning they would be at 80psi. FWIW. I'm not convinced that there was much difference to butyl either.

daniel_b

Thanks gents, and NO for your (as always!) detailed reply :-)

Yes good recall, that is pretty much my weight, or a tad under in the summer, and a bit over in the winter!

Interesting re pressures - I just found this Schwalbe chart, and they seem pretty high for a 60kg rider no?

My road bike has 23mm tyres fitted, and according to that I should be running at around 103psi (for the rear I am assuming) and from that I would assume 93ish for the rear - I think that would be pretty unforgiving.

I think I have run the 23's at 90 \ 80, and also run the same pressure for the 25's on aero bike with latex tubes, as I feel bing aero it deserves the extra pressure - stoopid I know.

I've only ridden on them twice so far, and of course I don't have a direct comparison as that bike has always had latex tubes - it did feel fast, but then it's a fast bike, and it was new, so it would do I guess!
All reviews, and tests (That I have read) on line seem to support the 5w per wheel advantage thing.
I know most people will see that as lame, and that's their right of course, but havng spent a (to me) lot of cash on this bike, and put deep rims on etc etc, I want to maximise it's ability to make me go fast.
The results come out on Strava :-) Which I am marginally addicted to.

I should be completing a 2.5 - 3 hour ride in the next 3 weeks, so will get a good feel for the loss there, just wondered if anyone had any experience already.
I guess that will tell me whether it is anything major to worry about or not - I suspect not.

6 hours is hopefully conservative, but I've never ridden the roads before, and don't know what my starting time is yet - I gather the later you go, the more tricky a 'fast' time is.
My initial plan is to take it easy-ish for the first half, and then see what I have left energy wise, and finish giving it full beans.
I'll probably get caught up in all the excitement, go way too fast in a group I can't possibly keep up with for 100 miles, get spat out the back, forget to eat, and then end up bonking and limping home!

@PBlakeney - was that 20psi loss after 24 hours AND a days riding I assume?

daniel_b

This looks a bit more normal:


That would put my 23 shod bike at around 97 \ 74
And the 25's at 82 \ 60

Seems a bit of a larger differential than I would normally go with.

pblakeney

Too much to edit on a phone.
My 100-80psi drop was a full day ride & overnight although they did feel squishy by the time I got back to the hotel so possibly most of the drop was during the ride.

webboo

Don’t tubs have latex inners and you don’t often see a pro race where they all have to stop and start pumping up their tyres.

Matthewfalle

depends which tubs

#slowdeflation

w00dster

I've probably been wrong all these years, but and I have zero science of fact behind this......I always thought that when moving there was very little loss of pressure. It was when the tyre was sat stationary...I realise how daft that sounds, but I've never noticed any loss of pressure during a ride (or at least not a noticeable loss) - that includes long rides, but when left overnight the tyre then needs topping up?

I'd also not think you would really notice if you are losing 20 psi over 24 hours, so if you pump up to 103 psi, during the ride all things being equal you'd lose less than 8 psi. So you'd finish the ride at 95psi - not sure you would notice that, I know I wouldn't.

drlodge

What are these tube things you speak of?

#tubeless

homers_double

Matthewfalle wrote:

if you're that worried why just not pop some butyl ones in? one less thing to worry about.

That's what I thought :?

sungod

Webboo wrote:

Don’t tubs have latex inners and you don’t often see a pro race where they all have to stop and start pumping up their tyres.

as mf says, not all use latex, but the ones big teams use will be latex tubed, from veloflex, vittoria, dugast etc. (possibly rebranded)

afaik conti don't have their own latex tubes, but they buy in others and put them in the 'pro ltd' tubs they issue to teams, i.e. the conti competitions you see in a big race are not the same as ones on sale from wiggle etc.

mercia_man

Pressure loss for me with Michelin latex tubes is no problem. As said earlier, you might lose 5-10 psi max during an all-day ride.

keef66

Daniel B wrote:

This looks a bit more normal:


That would put my 23 shod bike at around 97 \ 74
And the 25's at 82 \ 60

Seems a bit of a larger differential than I would normally go with.

Just by trial and error I've arrived at 80 rear / 65 front for my 25s, so I'd say it's about right for me.

daniel_b

homers double wrote:

Matthewfalle wrote:

if you're that worried why just not pop some butyl ones in? one less thing to worry about.

That's what I thought :?

Wouldn't say I am worried, more curious, and hence the question

keef66 wrote:

Daniel B wrote:

This looks a bit more normal:


That would put my 23 shod bike at around 97 \ 74
And the 25's at 82 \ 60

Seems a bit of a larger differential than I would normally go with.

Just by trial and error I've arrived at 80 rear / 65 front for my 25s, so I'd say it's about right for me.

I may experiment a bit more then, I usually only have a 10psi differential.

mugensi

I've been using Vittoria latex tubes for years and usually get 3 to 4 days use before having to pump them.

For example, last Saturday morning I pumped them to 75/65psi (R/F) and went for a 70km spin, I wasn't out again until Tuesday evening and checked them by testing how firm they were and they seemed fine and solid so I didn't bother pumping them again and went on a 30km spin. I wasn't out again till yesterday evening (Thursday) and I stuck the pump on them and the front wheel was at 40psi and the rear at 55psi so I pumped them again.

I have the same Vittoria latex tubes on both my road bikes and I cannot remember any instances where I had to re-inflate them two days in a row, I always get 2 or 3 days at least between having to.

You'll be fine on a 6hr ride.

N0bodyOfTheGoat

While trying to convince myself to head out to the South Downs this afternoon, despite the miserable overcast weather, I've just swapped the rear tube back from the latex to the 25-32mm... It was dropping to ~40PSI from ~105 over a few days, so something isn't right. I'll check for an air leak later.

There's now a regular pattern of miniature rectangle bulges on the removed latex tube, where the tube would have been contacting the Hunt Aero Light Disc (Kinlin) rim well, yet the pre-installed tubeless tape in the rim looked fine during the swap over.

mercia_man

That pattern on the tubes is normal - mine look like that where the rim tape indents slightly on the spoke holes. I always pump them up to correct pressure before every ride. I can’t leave them for several days. One advantage of latex tubes is they are more resistant than butyl to intrusion punctures because they are so stretchy and less likely to suffer pinch punctures if, for example, you hit a pothole or cattle grid. I can also definitely feel they give a better ride when fitted to flexible race tyres. Not so for stiffer tyres.

mugensi

NitrousOxide wrote:

While trying to convince myself to head out to the South Downs this afternoon, despite the miserable overcast weather, I've just swapped the rear tube back from the latex to the 25-32mm... It was dropping to ~40PSI from ~105 over a few days, so something isn't right. I'll check for an air leak later.

There's now a regular pattern of miniature rectangle bulges on the removed latex tube, where the tube would have been contacting the Hunt Aero Light Disc (Kinlin) rim well, yet the pre-installed tubeless tape in the rim looked fine during the swap over.

40psi over a few days from 105psi is normal and nothing to be concerned about. The higher a latex tube is pumped the quicker it will lose air as the latex is stretched more and so slightly more porous. Like I said above I can get 3 or 4 days from 75/65psi in my latex tubes.

svetty

MugenSi wrote:

The higher a latex tube is pumped the quicker it will lose air as the latex is stretched more and so slightly more porous.

Really? You think the outer tyre stretches significantly when you increase the pressure? If not how does the latex tube stretch more?
Granted higher pressure means more leakage but this is down to pressure not stretching.

Alejandrosdog

You’re going to need to stop and pump them up. If you haven’t got a full size frame pump, take your trac pump and bungee it to your bike.

#firstworldpanic

imposter2.0

MugenSi wrote:

The higher a latex tube is pumped the quicker it will lose air as the latex is stretched more and so slightly more porous.

Unless the tyre stretches at the same rate as the inner tube (which is obviously not the case), then this is not correct.

philbar72

they lose pressure daily. top them up and keep an eye on them.