Forum home Road cycling forum Road general

Latex tube pressure loss

N0bodyOfTheGoatN0bodyOfTheGoat Posts: 4,256
edited May 2019 in Road general
Decided this morning it was time to put the summer tyres back on the Cube, a pair of 700x28 GP4000S IIs bought and used last summer, along with the pair of Vittoria 25-28mm latex tubes fitted with these tyres last year.

At ~0830, I inflated them to ~95PSI front and ~100PSI rear.

Just thought I'd check the pressures at ~1715, before thinking about getting changed for an early evening ride, to find the front has dropped to ~80PSI and the rear to ~70PSI! :shock:

I was aware of this pressure drop last summer, albeit not to this extent, often inflating to similar ~95/100 front/rear (when I was ~78Kg rather than ~81.5Kg currently) to allow for ~10PSI drop over a ~3-hour ride.

In contrast, I've been using cheapy Valvert 25-32mm butyl tubes with "28mm" GP 4 Seasons (that measure ~29mm wide) at ~90/95PSI since around early November and they barely drop any pressure between bi-weekly checks with the same track pump.

Now "28mm" GP4000S IIs measure ~31mm in the real world... Is this extra volume stretching the Vittoria tubes so they diffuse air even quicker, or is it more likely I have a micro-punctures (didn't need to use levers to install today, but did last year IIRC)?

I guess I could test the diffusion theory by using the 4 Seasons with the latex tubes, but was keen to feel the ~20W (going on https://www.bicyclerollingresistance.com/ ) reduction in rolling resistance... I need all the help I can get after a ~13% drop in my 20mins power after my early March to early May lurgy! :lol::cry:
================
2020 Voodoo Marasa
2017 Cube Attain GTC Pro Disc 2016
2016 Voodoo Wazoo

Posts

  • pblakeneypblakeney Posts: 13,210
    Temperature will have an effect.
    #normalforlatex
    The above may be fact, or fiction, I may be serious, I may be jesting.
    I am not sure. You have no chance.
    veronese68 wrote:
    PB is the most sensible person on here.
  • zefszefs Posts: 484
    It's recommended to change latex tubes after a year as they expand with heat even if they were not used.
  • OnTheRopesOnTheRopes Posts: 460
    Why not try Conti Supersonic tubes, lighter than latex and less prone to lose air.
  • daniel_bdaniel_b Posts: 8,659
    Can't recall the brand I have inside a pair of 4000's, but yes exactly the same experience as you.
    Felt F70 05 (Turbo)
    Marin Palisades Trail 91 and 06
    Scott CR1 SL 12
    Cannondale Synapse Adventure 15 & 16 Di2
    Scott Foil 18
  • sungodsungod Posts: 12,828
    latex tubes lose pressure much faster than butyl, sounds perfectly normal

    you can try larger diameter tubes, might slow it a bit, but they'll still lose pressure
    my bike - faster than god's and twice as shiny
  • N0bodyOfTheGoatN0bodyOfTheGoat Posts: 4,256
    I was used to topping them up before each ride and even during the odd longer 4+ hour rides last summer, but to discover ~30PSI loss on the rear after ~8 hours today seemed a bit crazy.

    The Valvert tubes they replaced are ~150g compared to the latex ones being ~75g each, will see how things go over the next few days or so... Beginning to remember getting a bit peeved with this pressure loss last year and contemplating ditching the Vittorias.
    ================
    2020 Voodoo Marasa
    2017 Cube Attain GTC Pro Disc 2016
    2016 Voodoo Wazoo
  • david7mdavid7m Posts: 636
    Are you racing? Can you tell the difference between inner tube materials?
  • chrisw12chrisw12 Posts: 1,246
    When I was riding a lot, I could definitely feel the difference. I’d sometimes change to latex for race days (tt’s). I’d train on the Tt bike and same front wheel so it wasn’t a race day thing.

    I used to think the loss of pressure was a good thing for long races. Start on the high side when you’re fresh, then the loss of pressure would give a bit more comfort as the ride went on. On 21mm tyres everything helped :D
  • zefszefs Posts: 484
    Shouldn't be 30psi overnight though, I remember mine losing 5-10psi max (Vittoria/Michelin).
Sign In or Register to comment.