Two Wheel Blogs

We've had a really nice run of 3 days here where the weather's been too good to pass up. Being one to take advantage of a good situation, I did my own little training camp, piling up nearly 150 TSS per day. Needless to say, today's rain showers didn't bother me a whole lot. A little spinning on the old rollers was just the ticket for me this afternoon.

So there I am, riding my rollers and enjoying whatever iTunes happens to serve up, and I notice a certain ticking sound coming from my front wheel area.

Now a ticking sound, one that repeats with every rotation, can't be good. I looked at the brakes. They had clearance. There's no computer pickup on the fork at all so that couldn't be it. "Could be in the hub" I tell myself. Hmm, that's really not good.

So then I start thinking that if something really is wrong with my front wheel I don't want to be making it worse by riding on it. And if it really is something wrong in my front hub or somewhere in my front wheel it'll stop if I switch to another wheel. After all there is this small chance it might be the rollers, right? Process of elimination. Plus I get to practice stopping and starting on these rollers.

I stop and dismount, which looks a lot like falling off my bike while I'm learning to ride rollers, so I can go get another front wheel. I put an old wheel from another road bike in the fork drops and clamp it down. Ten minutes later I'm back on the rollers spinning once again. (Hey, I said I'm still learning to ride rollers.) Good news. No ticking sound. Or maybe I should say bad news. There's a ticking sound in my new front wheel. But that's not what this story is about. Right? I mean the title says this is about rolling resistance.

Now that I have vanquished the ticking sound to address later, after my recovery ride and I'm back to spinning, I noticed it feels a lot harder spinning with this different front wheel. I checked my SRM and you know what I found? In order to go the same speed/cadence as I had been with my new front wheel I now had to pedal at a significantly higher power. The screen capture is my before and after wheel change power chart. It illustrates the difference.

And the difference, of course, is rolling resistance. Maybe not entirely, but surely the majority of the difference. The torque required to turn my new wheel, new as it is, just isn't that much less than it is to turn the old one. The difference - and what you're looking at here is a difference of more than 15% - is rolling resitance. I hadn't taken the time to check air pressure in the older wheel. It wasn't down by much. Just a stroke and a half from my floor pump brought the pressure back to 100psi.

I never really gave it much thought; but now I have seen (and felt) it for myself. A few pounds of air pressure in a bike tire can have a huge effect on power required to go fast on a bike.

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