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Discussion: lighter machine

in: PG; PG > 2016-10-03

Oct 4, 2016 7:15 AM # 
Alternatively you could get a heavy machine with some electrical assistance. That would also make going up the hills more fun.
Oct 4, 2016 5:09 PM # 
There are lots of articles on the internet about how much faster you climb on a lighter bike. The answer is pretty much: a lot less than most cyclists think. And not enough to account for the difference between us Sunday or at Greylock. Here's an example. Indeed, I gained more time from losing five pounds over the summer than the gain I get from a lighter bike. But, of course, seconds matter when you're competing (with me :-) ), and not just biking for exercise.
Oct 4, 2016 5:45 PM # 
You need to find a place where you can demo a fancier bike to see if it's to your liking. My father was a big fan of lightweight bikes, but I find that there's a much more noticeable advantage to be had from better tires/wheels.
Oct 4, 2016 6:03 PM # 
I forgot one other consideration -- the damage it would do to Phil's self-esteem if I could keep up with him. :-)

Perhaps best leave things as they are?
Oct 4, 2016 7:06 PM # 
And then there's the underlying question: is going fast the real point?
Oct 4, 2016 9:03 PM # 
Going fast enough to make it seem fun is certainly at least part of the real point. And what is fast enough to make it fun may depend a little bit on whether you are riding with somebody else, and how fast they are going!

An amusing point about the example quoted above by Phil is that they never tell you the length of the climb that is being done on several bikes of different weights--just the number of seconds saved.

The main place where rather tiny differences in bike performance make a real difference is when you are riding with a group in a pack or a pace line, and a percent or so in speed may make the difference in whether you can stay in the draft, or just can't quite. Wind resistance is where most of the work comes in on flats and downhills, and it becomes very important to be capable of staying with your group on the uphill bumps in something more like a racing environment, because if you are even a little way off the back when the hill crests, it is more than likely you will be out of sight by the bottom.
Oct 4, 2016 9:39 PM # 
Eric: The caption says it was one mile.

J-J: I upgraded to lighter wheels too :-) (Though I wasn't willing to splurge for carbon.) Another article I came across showed that taking the weight off the wheels made a difference, but not as much as I would have thought. (But maybe conclusions drawn from the ride with water in the tires are bogus.) Where it makes a big difference is with quick acceleration, which is useful when I first take off from Peter on the climb and leave him in the dust :-)
Oct 4, 2016 10:01 PM # 
Higher pressure (typically narrower) tires really feel different. Once you get moving, rolling resistance is small compared to aerodynamic drag, but you lose proportionally more time in the sections when you're moving slowly. If nothing else, it makes sense to always be sure that you're tires are properly inflated. (I'm always having to resist the urge to do thins with my mountain bike, where you want your tires to be somewhat soft.)
Oct 5, 2016 12:18 AM # 
Phil, thanks for pointing out where to look. Apparently it is not just on orienteering maps where I miss some of the important details when looking at them too quickly!
Oct 5, 2016 12:33 AM # 
Another important factor in that article is that it depends a lot on how close to maximum power 200 watts is for the rider in the test. If that is well within his limits, of course the efficiency of the ride is essentially unchanged by a percent or two change in the weight being lifted up the hill, and the time difference should naturally reflect the same percentage change. Things go very non-linear when you start approaching your maximum output power (as may likely happen when pushing hard on a hill), and the efficiency under increased loading will drop drastically. So a more interesting test would be to have the rider go up the hill on the lightest bicycle at the very maximum power output he could sustain on the power meter for the mile climb, then see what the time difference was when he tried it with an extra three pounds of bike weight.
Oct 5, 2016 12:57 AM # 
Actually, the most interesting test would be for me and Phil to just change bikes (and shoes) and go at it. :-)

But I think Eric has a good point. Certainly going up a good hill I am close to (or at) my limit.
Oct 5, 2016 2:55 AM # 
I think you might have trouble with the size of Phil's bike, either straddle height or handlebar reach or both.
Oct 5, 2016 4:20 PM # 
I'd waste your money on the wheels and tires first. The rotating bits feel heaviest.
Oct 5, 2016 4:51 PM # 
Maybe just need to take some hose clamps and strap a 6 pound chunk of metal onto some convenient part of Phil's frame (his bike frame, I mean), and see how it goes when his bike is 3 pounds heavier than yours, rather than 3 pounds lighter. If nothing else, it would give a small boost to Phil's conditioning efforts for the day!

JJ and Alex are right that tires can make the ride feel really different. But not all narrow, high-pressure tires are the same, even for the same weight. Somehow the fabric and the layering of the rubber can be done in ways that allow a lot of squirm in the rubber, resulting in a much lossier ride. It may be there are factors related to trade-offs in puncture resistance and traction that come into play in addition to cost of fabrication..

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