Lower PSI but faster?

Kiblams
Kiblams Posts: 2,423
edited May 2009 in MTB general
I put a 26x2.5 tyre back on the front of my bike and pumped it up to 50PSI in the hope that it would roll easier than I remember, but after riding out yesterday I was finding it very difficult to accelerate and when upto speed; staying there. So in despair I let the tyre down to 30PSI and instantly the bike seemed more responsive and generally nippy.

My Kenda Komodo 26x1.95 are alot faster when pumped up to higher PSI and I was under the impression that this was the norm. Has anyone found that some tyres that are faster when lower PSI before?

Comments

  • Raymondavalon
    Raymondavalon Posts: 5,346
    My synopsis of the situation is that under higher pressure the rear tyre is losing traction, lowering the PSI gives the tyre more surface area, therefore more grip - assuming you're riding on dirt.

    Another thing could be that under higher pressure, you're riding on the centre block/blocks of the tire and they are causing resistance on the riding surface through friction etc. Lowering the pressure makes the centre blocks less prone to resistance increasing the rolling momentum.

    If my two theories don't quite hack it, I would perhaps put it down to the overall setup suiting YOU as the rider, a bit like the way some F1 drivers prefer a softer tyre on certain circuits.
  • Kiblams
    Kiblams Posts: 2,423
    My synopsis of the situation is that under higher pressure the rear tyre is losing traction, lowering the PSI gives the tyre more surface area, therefore more grip - assuming you're riding on dirt.

    This might be the case if I was using the new tyre on the back of the bike. Your second theory makes more sense, it is a downhill tyre so maybe it was designed to be run at lower PSI (only lists a Max PSI, which is 65)

    Confused the hell out of me is all.
  • Kiblams
    Kiblams Posts: 2,423
    The Schwalbe document listed on that thread makes alot of sense after my experiences lately. Cheers for the link nfrang.