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Too much sag while riding..(on bicycle)

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  • 04-09-2012 4:45pm
    #1
    Zyzz
    Registered Users Posts: 2,874 ✭✭✭


    Im 97kg, tyres hold 120 psi and the most Ive had in them was 100 but still when Im cycling it feels (and looks) quite saggy. It is affecting my speed, times and distances :/ I know there is meant to be a % of sag but it is annoying..

    I know the more I put into them the higher risk I have of blowing it if I have the misfortune of hitting a hole. Is there a specific tyre/tube setup that I can get that can hold my weight with ease and remove the sag?

    (Current: Continentals with 700 x 20/28c presta valve tubes)


Comments

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    #2
    Lumen
    Registered Users Posts: 31,008 ✭✭✭✭Lumen


    You won't blow a tyre at 120psi by hitting a pothole, in fact you're much less likely to get a pinch flat.


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    #3
    AaronB
    Registered Users Posts: 110 ✭✭AaronB


    im down from 115kg to 103kg, alot of hard work over the summer. but i pump mine just over 120psi as you'll lose abit taking the pump off.

    I went for strong tyres the gatorskins, been using them for over a year now on really crap roads, never got a flat or a puncture.

    When i bought my defy 1, the tyres that came with that, i had blow outs :( so just buy good strong tyres and you'll be fine.


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    #4
    Cyclepath
    Registered Users Posts: 333 ✭✭Cyclepath


    +1 I'm down from 112kg to 105kg with the daily commute but I've always put 115psi into my tyres (currently trying out the schwalbe marathon plus).

    No probs running that pressure, though there will always be a bit of sag when you're tipping the 100kg mark!


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    #5
    Cee-Jay-Cee
    Registered Users Posts: 12,235 ✭✭✭✭Cee-Jay-Cee


    Pump them to the max pressure, they're designed to take they pressure and will work better. You'll notice a big difference!


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    #6
    Zyzz
    Registered Users Posts: 2,874 ✭✭✭Zyzz


    Thanks for the replies fellas


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    #7
    doozerie
    Registered Users Posts: 4,830 ✭✭✭doozerie


    Of the various tyre pressure guides available, the Michelin one that I linked to in this post suggests that if you are over 82kg then inflate the tyre to the max pressure specified on the sidewalls.

    For lighter riders, inflating to max recommended pressure can actually have the effect of reducing speed, as discussed in the quote from the Zipp website in that same post.


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    #8
    Dubba
    Registered Users Posts: 895 ✭✭✭Dubba


    I do 120 at the back and 110 on the front, re-inflate after a couple of rides as the pressure does seep out somehow.


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    #9
    AaronB
    Registered Users Posts: 110 ✭✭AaronB


    re-inflate after a good cycle, mine drops 10psi for an avg 2-3hr cycle, went your a heavy guy like me you need to keep it to max pressure.
    and lift your ass off the saddle slight on very bumpy roads (when you can), so your rear wheel wont take all the impacted, haven't broke any spoke since i started doing that.


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    #10
    Zyzz
    Registered Users Posts: 2,874 ✭✭✭Zyzz


    Right so I'll stick in 110+ and see how I go! Got a feeling I'll be throwing in a new tube though :pac:


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    #11
    Cee-Jay-Cee
    Registered Users Posts: 12,235 ✭✭✭✭Cee-Jay-Cee


    Zyzz wrote: »
    Right so I'll stick in 110+ and see how I go! Got a feeling I'll be throwing in a new tube though :pac:

    Why 110 when the tyre takes 120. It will do no harm and pumping to the max pressure prevents pinch punctures. I keep my Tyres at the Max all the time (I'm 80kg)


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  • Options
    #12
    Zyzz
    Registered Users Posts: 2,874 ✭✭✭Zyzz


    CJC999 wrote: »
    Why 110 when the tyre takes 120. It will do no harm and pumping to the max pressure prevents pinch punctures. I keep my Tyres at the Max all the time (I'm 80kg)

    ..I will put in 120 tomorrow and see what happens :pac:


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    #13
    Lumen
    Registered Users Posts: 31,008 ✭✭✭✭Lumen


    CJC999 wrote: »
    Why 110 when the tyre takes 120. It will do no harm and pumping to the max pressure prevents pinch punctures. I keep my Tyres at the Max all the time (I'm 80kg)

    Higher pressure gives worse ride quality and (sometimes, probably) less grip.


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    #14
    mossym
    Moderators, Sports Moderators Posts: 8,766 Mod ✭✭✭✭mossym


    Lumen wrote: »
    (sometimes, probably) less grip.

    think the mtb'ers are proof enough there, run lower pressure to get more grip...


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    #15
    Lumen
    Registered Users Posts: 31,008 ✭✭✭✭Lumen


    mossym wrote: »
    think the mtb'ers are proof enough there, run lower pressure to get more grip...

    I think off-road is a bit different - there's some rule of thumb that your tyres should be as soft as the ground you're riding over.

    Lower pressure necessarily means more contact area; I don't understand the physics of tyres well enough to know what that means for rolling grip at the limit, but empirically I tend to get more rear wheel slippage on the road using 23mm slicks at 100psi than I do using 35mm slicks at 70psi.


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    #16
    monkeypants
    Closed Accounts Posts: 2,386 ✭✭✭monkeypants


    I run my Ultremos at approximately 130, front and back, and I haven't had a blow-out yet.

    * touches wood with crossed fingers *


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