Singletrack Mountain Bike Magazine

• Overview
• Bike Forum
• Chat Forum
• For Sale
• Wanted
• Forum Help
• Classified Rules

Bike Forum

1. bowglie - Member

   ok, please excuse my ignorance on this topic. er..warning, this is a bit of a 'is it normal/how does it work' anorak thread. I've just got back from my first 'tubeless' ride and well, what a different feel the bike has now.

   I don't know if it's my imagination, but it felt like the bike had less rolling resistance but substantially more grip. Is it just me, or have other people noticed this with tubeless?

   I'm try to get my pea brain around the physics of this - how can such a reduction in rolling resistance be accompanied by a significant increase in grip??

   I also noticed that for the same pressure, the tubeless tyres feel a lot firmer than tubed (fwiw, I ran 20psi front/25psi rear). However, even with the tubeless feeling firmer than I normally run tubed, there was still loads more grip - er...can anyone explain why? and why should the tyre feel firmer at the same pressure?

   Posted 2 years ago #
2. RealMan - Member

   Removing the tube removes some rotational weight. This decreases rolling resistance.

   Removing the tube causes the material in contact with the ground to be thinner (instead of tyre and tube, its just tyre). This means the material (the tyre) is more supple, and can deform better to the trail. This increases grip, and decreases rolling resistance.

   As for firmer tyres under the same pressure.. I don't know, doesn't sound right. Were you using different tyres?

   Also, if you were using different tyres, the extra grip and decreased rolling resistance may be due partly to them, as well.

   Posted 2 years ago #
3. bowglie - Member

   Hmm..yes, the mechanics of the more supple tyre moving over the ground makes sense.

   The tyres are the same ones (non-UST Kenda Nevegals) that I was running with tubes - so I'm not sure what's causing the the tyres to feel firmer at the same pressure (might be just me of course! - I'm just going to let a bit more air out of them anyway, but I just wondered if anyone else had noticed a pressure disparity?)

   Posted 2 years ago #
4. scaredypants - Member

   As for firmer tyres under the same pressure.. I don't know, doesn't sound right

   agreed

   When I've used them, feels like I should increase pressure - have said loads of times on rides that it feels like I'm getting a flat. That's much more noticeable than RR or grip IME

   Posted 2 years ago #
5. Scienceofficer - Member

   Its reckoned that the removal of the tube makes the tyre more flexible and more able to conform to micro terrain, effectively reducing the need to ride 'up' loads of micro steps.

   At the same time, because the tyre deforms more, it has a larger contact patch, increasing grip.

   IME, a tubeless tyres sidewall thickness/stiffness will have a greater influence on how it rides than if it were tubed. With double ply tyres and low pressures, you're riding on the stiffness of the sidewalls as much as the air pressure.

   Without knowing the specifics of the equipment you were using pre and post tubeless, its hard to comment on the 'firmer feeling' thing.

   Posted 2 years ago #
6. orange - Member

   I don't know if it's my imagination, but it felt like the bike had less rolling resistance but substantially more grip. Is it just me, or have other people noticed this with tubeless?

   no its not you! i find this as well!

   Posted 2 years ago #
7. owenfackrell - Member

   As for firmer tyres under the same pressure.. I don't know, doesn't sound right. Were you using different tyres?

   
   Also agree as i find it the other way round.
   I am just about to try a getto conversion on them HT as i dislike the feel (and getting punctures) of a tube tyre now as i have been running tubeless on my FS for over 2 years.

   Posted 2 years ago #
8. thesurfbus - Member

   I have just converted a set of Panaracer Fire XC Pro to Ghetto Tubeless. I can't say I noticed them rolling faster, but they are lighter, so they must be faster. One thing I noticed was how much more flexible the tyre wall is, so having to run them at 40PSI (was 37PSI)to stop the tyres feeling like they are rolling off the rim. I have hit a few rock edges which normally would have caused a snake bite, and they seem to be holding air just fine. The other problem I have found was that one of the valves got clogged up with latex which had set.
   Going to stick with them and see how they feel longer term.

   Doug

   Posted 2 years ago #
9. orange - Member

   thesurfbus - Member
   The other problem I have found was that one of the valves got clogged up with latex which had set.

   i have read that a new product may resolve this, i've not tried it myself (think its only in the USA at the mo) but it is called CaffeLatex - it foams up inside the tyes when they are rotated

   Posted 2 years ago #
10. 13thfloormonk - Member

    I can offer a theoretical but completely BS reason for the feeling firmer thing.

    By removing the inner tube you have very slightly increased in the internal area of the tyre/rim. The same pressure acting over a slightly greater area will result in a greater force applied against the inside of the tyre, making it feel firmer.

    This effect explains why road tyres can run 120p.s.i (small internal area) and tractor tyres explode at 10 p.s.i (huge internal area).

    If i've got any of that wrong, sue me, its friday

    Posted 2 years ago #
11. votchy - Member

    I agree with the OP about feeling firmer, having run Nevegals with tubes then converted to ghetto, 30psi in tubeless felt, to my calibrated right handed squeeze, to be the same as 40psi with tubes.

    Posted 2 years ago #
12. bowglie - Member

    13thfloormonk - nice one! sounds plausible to me, but then my maths & physics brain cell has just shut down for the weekend.

    Glad it's not just me that's noticed this pressure & grip difference. I know the increase in grip is mentioned on places like Stan's & NoTubes websites, but I wondered how much was just marketing bumf.

    The increase in grip caught me out. I'd just unloaded the bike to start my tubeless test-ride over an easy moorland track in the Peak - and there were a small group of fell runners waiting at the gate. So, being a stupid show off, I though I'd 'style it up' a bit as I rode off. I was just doing my usual trick of drifting the bike from one rut into another when the extra tyre grippiness struck and I had a comedy hopping up and down on the crossbar & slow speed endo.....what a p*****k

    Posted 2 years ago #

RSS feed for this topic

Topic Closed

This topic has been closed to new replies.