Ask the Expert Bike Tech: Flat Tires

Do you get flat tires on your bike and don’t know why?

This week’s “Ask the Expert Bike Tech (and Professional Bicycle Fitter)” comes from Bill who asks:

My son’s hybrid bike that he rides around campus is flatting on just about every ride.  It seems to be always flatting around the valve stem.

It is an older hybrid bike, with 700 x 35c tires on it (somewhat knobby tires).  Recommended tire pressure on the tire is 50-75PSI, I suggested he run at the low end (~50psi) of this in case impacts are causing flats, but the flats continue.

This past weekend we ran a new rim tape around, replaced tire, got it back together, his first ride to campus – flat again.  We cannot find any burrs or edges on the wheel itself, and the tire seems fine.

Our resident Bike Guru, Victor, had this to recommend:

If you have any questions about the mechanics of your bike or improving the fit between you and your bike, please be sure to send them in to Ask the Bike Tech. Consider Victor your own private bicycle expert and professional bike fitter.  Send your questions to:

  • Anonymous

    Cool video. I’ve had a real problem with flats recently too – but I think it was mostly bad luck, although I’ll be sure to check my valve as well. One thing I really struggled with was getting my wheel off though – so much so that I’ve actually switched to a new kind of bicycle quick release that has made it way easier for me. All the same, would love to see a video on QRs. Cheers!

    • Darryl is Loving the Bike

      Thanks for your comments.  Victor will definitely get back to you on this with a video on Quick Releases and it will be featured in an upcoming “Ask the Expert Bike Tech”.  I’ll let you know when it’s up.

  • voucher

     From a mechanical viewpoint, up to 99% of the energy delivered by the rider into the pedals is transmitted to the wheels, although the use of gearing mechanisms may reduce this by 10–15%.

  • Steve McCadden

    Your timing is impeccable.  I am fairly new to road cycling and I had a very similar thing happen to me.  I think you just solved my problem.  Thanks guys.

    • Darryl is Loving the Bike

      Glad we could help out, Steve.  Be sure to let us know if you have any questions for Victor…we’re here to help out.