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My LBS sez the benefits of light-weight bicycles...(11 posts)

My LBS sez the benefits of light-weight bicycles...huffer
Sep 3, 2003 10:25 PM
are inversely proportional to the weight of the rider.
Scenario #1
A 200 pound cyclist is riding a 20 lb bike for a total of 220 lbs. If he/she were to shave off 2 lbs from the bike to create an 18 lb bike, then the total weight savings (rider plus bike)would be 1% (bike was 10% of total weight and is now 9% of total weight).

Scenario #2
A 125 lb cyclist is riding a 20 lb bike for a total of 145 lbs. If he/she were to shave off 2 lbs from the bike to create an 18 lb bike, then the total weight savings (rider plus bike)would now be 1.6% (bike was 16% of total weight and is now 14.4% of total weight).
By this logic, it would seem that lighter riders on a team riding the same bikes would be at more of a disadvantage than heavier riders because they have to propel a higher percent of inert mass (their bike). At the same time, the lighter riders seem to have the advantage of benefiting most from weight reductions, since pound for pound, the same reduction on a light riders bike will reflect a greater overall % reduction (and therefore less overall effort over an extended race).
Hmmmm.
re: My LBS sez the benefits of light-weight bicycles...tube_ee
Sep 3, 2003 11:07 PM
Your LBS is right. It is the total mass of the system that is important, and the bike is a very small portion of that mass. I'm not sure what you mean by saying that the lighter riders on a team would be at a disadvantage if all riders were on the same bike. The total mass of their system is still less. And while it is true that the bike is an inert mass, so is most of the rider.

And even with these two extreme examples, note that 125 lb rider only gets a 0.6% (.006) benefit over the 200 lb rider. For anyone but the most elite athelete, .6% is basically irrelevant. Even for the elite rider, the difference in performance on the lighter bike is probably due more to psychological factors than to physics. Which is not to say that psychology is not important to elite atheletes, it certainly is.

Also, losing 2 lbs off your bike will cost well over $1000. Losing 2 pounds off of the rider is free.

Just my $0.02

--Shannon "220 lbs, without the bike" Menkveld
overall weight not as important--power to weight ratio is (nm)ColnagoFE
Sep 4, 2003 7:00 AM
They are correct.MXL02
Sep 4, 2003 5:27 AM
Lightweight bikes make more of a difference for lightweight riders, and then mostly for climbing. Even Lance uses the heavier 5500 frame on the flats and reserves the flyweight 5900 for the mountains.
All weight is not created equalpitt83
Sep 4, 2003 5:41 AM
Depends on where the weight savings are. It's easy to oversimplify this. Yes, losing a few pounds from your body makes you faster (probably because you're now in better shape), but bike ewight is also important. The simple percentages equation is an over-simplification.

If you lose 20% of rotating momentum weight which you lift constantly (wheels), you make a huge difference in effort. Leaving your seatpack at home, carrying less water, or having a lighter frame makes a smaller difference.

Certain weight savings are important, mainly wheels.

IMHO and YMMV
YMMV ? (nm)PEDDLEFOOT
Sep 4, 2003 6:51 AM
Your Mileage May Vary (nm)pitt83
Sep 4, 2003 7:07 AM
All weight is not created equalasgelle
Sep 4, 2003 7:24 AM
What you say is simply not true.Where did you get the idea that where weight is located makes the slightest difference. Go to analyticcycling.com, plug in some numbers and you'll see that where you add the weight makes no difference. In fact Kraig Willet has shown that doubling the weight of a wheel only affects speed or power by about 2/10 of 1%
http://www.bike.com/template.asp?date=8%2F1%2F2001&lsectionnumber=6
Grant Petersen's been saying that for years.cory
Sep 4, 2003 7:26 AM
So have I, but nobody listens to me...
Seriously, though, it's so simple and obvious that it doesn't bear thinking about. I saw an ad the other day for a frame that was "20 percent lighter" than some other frame. Sounds like a lot--but it was only a few ounces, and while it's 20 percent of the weight of the bare frame, it's just about indetectable in the overall bike-rider-clothing-seat bag package.
LBS is right.bimini
Sep 4, 2003 8:04 AM
The major effect of this is who is in the position to loose 2 pounds of body weight.

A 200 pound rider most likely has 2 pounds of fat to get rid of without loosing any mussle mass.

A 125 pound rider probably does not have two pounds of body fat to give up. May loose more mussle mass than fat. The only place that rider can drop 2 pounds is off the weight of the bike without it effecting power output.
re: My LBS sez the benefits of light-weight bicycles...mapei boy
Sep 4, 2003 2:50 PM
I weigh 162 lbs. I feel a significant, unmistakable difference when I switch between my 18 lb. racing bike and my 22 lb. racing one. It is especially noticeable on hills. This is despite the fact that my 22 lb. bike is the one with the super-skinny tubular tires. Sure, other factors may be at work here. But still...peddling the 18 lb. one is a heck of a lot easier.