Total Weight Versus Bike Weight

[bobscott]

Belgian Knee Warmers is a site which almost always has a good read or video. Looking there today I got the following quote from a review of the Cervelo SLC-SL.

http://www.belgiumkneewarmers.com/2008/01/review-cervelo-slc-sl_25.html

"The difference between a 15 lb. bike and a 16.5 lb. bike is immediately apparent. That 10 percent increase in weight is significant enough to be noticeable to any rider."

I haven't ridden enough bikes of different weights to evaluate this statement but we're talking about plus or minus a couple of waterbottles here. Seems like a variation of the "placebo effect" to me.

I would love to hear the group think on this.

Thanks,
bobscott

[swoop]

padraig at bkw is a very skinny mofo and sensitive to the bike. you should have seen his face all puckered up on that cervelo from the noise. not a happy camper.
you'll notice it under acceleration on the steep bits. he didn't climb any faster on the cervelo.


15/16 lbs is more or less the same thing.

ride up a hill with two full bottles.
empty them and repeat.


feel the diff? when? can you quantify one as better in the absence of a day full of climbs and a finish line?

[J.Greene]

I can feel the difference between 15 and 16.5. I'm not any faster, but the bike feels different. Some people I think equate that feeling with speed. I try not to.

JG

[Volant]

I can feel the difference after a good dump too - it's all about the same.

[Bernie]

we did a ride on Wed. afternoon when the weather was the best it would be for two weeks, me and two friends. As we got to one intersection a rider turned ahead of us, looked back, stood up and started to try and move away. Knowing my buddy in front wouldn't let a rabbit move away like that I just sat on as the pace picked up. When he pulled off I looked down at my computer so I could continue to hold the pace and I closed the last several hundred feet at 28mph. I was riding my commuter bike (cause that's all I had at work when I got the call they were going to ride), an early 80's steel Fuji with 8 sp, 32 spoke wheels laced on heavy rims, Time mountain pedals, frame pump, rack and all. Whole rig tops 30 pounds. I never thought about it or missed a beat. I probably would feel the difference on a long climb, but on rollers or normal flats it doesn't matter. BTW, my nicer road bike weighs 16.9 pounds with pedals in a 59 frame. I can certainly tell the difference from a dead stop, but when rolling it's just a bike to me.

[bostondrunk]

I can feel the difference between 15 and 16.5. I'm not any faster, but the bike feels different. Some people I think equate that feeling with speed. I try not to.

JG

Exactly. I think it has to do with the feeling of moving the bike side to side underneath, like when standing. It will feel different, but you ain't gonna go any faster forward.

[Karin Kirk]

"The difference between a 15 lb. bike and a 16.5 lb. bike is immediately apparent. That 10 percent increase in weight is significant enough to be noticeable to any rider."



This assumes that every other variable is the same? Same frame, same build, same wheels, same psi and same amount of snap in the rider's legs that day.

There are lots of differences that you'd notice between two given bikes. I'm not sure exactly how you'd attribute the difference in feel to weight alone.

[sg8357]

When I get to 5% body fat, I'll start buying stupid light German tweak parts, until that happy day, I won't worry about it.

Tires, tire pressure and bike luggage, those I'll obsess about.

Scott G.
It is a balmy 25f in Zinzinnati, we're havin' a heat wave.

[Tobias]

I would love to hear the group think on this.

Thanks,
bobscottThe main reason a rider can detect relatively small differences in bike weight which are near insignificant as part of the total weight is actually due to conservation of momentum. That law of physics also explains why so many swear that light wheels makes them accelerate so much faster when in reality it is impossible for them to make such a difference.

That 10 percent difference in bike weight between 15 and 16.5 pounds should be perceptible to most (as if you picked the bike up to place on a roof top rack), but as only about 1 percent of the total it won’t be perceptible with any accuracy. If you pick up a weight that is 165 pounds and another that is 166.5 pounds you can’t tell much difference.

Having said that, the lighter bike will climb incrementally faster if everything else is equal. The difference may not be perceptible, but it can be calculated. On a very steep – and therefore slow -- climb that takes 166.5 minutes to complete you may save close to 1.5 minutes – or something very close to that. To a professional racer that’s significant.

[swoop]

the funny thing is i put more time into bkw on the climb with him on the lighter bike.

its complex. numbers are numbers. his other bike prolly fit better.

[fiamme red]

Exactly. I think it has to do with the feeling of moving the bike side to side underneath, like when standing. It will feel different, but you ain't gonna go any faster forward.I think Tom Kellogg made the same argument regarding compact frames:

http://spectrum-cycles.com/616.htm

The big change [on the compact frame] came when I stood to accelerate or climb. As I stood up, the bike appeared to loose three pounds. The inertia of the bike as I rocked it back and forth was reduced so much that I felt as though I was on a twelve-pound bike. Interestingly, when seated, a compact frame feels exactly like a traditional design. The compact design has no effect on handling beyond the increases responsiveness during climbing and accelerating.

[Tobias]

its complex.How so? :confused:

When the discussion is based on "everything else being equal", then the “weight issue” is quite simple. To insert other variables into the discussion as many do is misleading at best; or maybe a smokescreen to hide deficiencies. Simple can remain simple, and there are very few things simpler than weight when evaluated as a stand-alone issue.

[cadence231]

There needs to be a bike weight section so you guys can have your own discussion group. :banana:

[brians647]

This assumes that every other variable is the same? Same frame, same build, same wheels, same psi and same amount of snap in the rider's legs that day.

There are lots of differences that you'd notice between two given bikes. I'm not sure exactly how you'd attribute the difference in feel to weight alone.

Well put. I totally agree.

[flydhest]

This assumes that every other variable is the same? Same frame, same build, same wheels, same psi and same amount of snap in the rider's legs that day.

There are lots of differences that you'd notice between two given bikes. I'm not sure exactly how you'd attribute the difference in feel to weight alone.

define "snap."

:)

[WadePatton]

Having said that, the lighter bike will climb incrementally faster if everything else is equal. The difference may not be perceptible, but it can be calculated. On a very steep – and therefore slow -- climb that takes 166.5 minutes to complete you may save close to 1.5 minutes – or something very close to that. To a professional racer that’s significant.

This assumes that the rider will put out the exact same amount of power on either bike--and will reduce gearing or cadence on the heavier bike. I just don't buy the time analysis. I would buy an energy expenditure analysis, but I find too many variables to swallow the time analysis. atwo

[flydhest]

Having said that, the lighter bike will climb incrementally faster if everything else is equal. The difference may not be perceptible, but it can be calculated. On a very steep – and therefore slow -- climb that takes 166.5 minutes to complete you may save close to 1.5 minutes – or something very close to that. To a professional racer that’s significant.

Which climbs are almost 3 hours? And your comparison means it would have to be a time trial, without team mates or other psychological effects going on, right?

[swoop]

How so? :confused:

When the discussion is based on "everything else being equal", then the “weight issue” is quite simple. To insert other variables into the discussion as many do is misleading at best; or maybe a smokescreen to hide deficiencies. Simple can remain simple, and there are very few things simpler than weigwhen evaluated as a stand-alone issue.

this is true except for "everything else being equal". i haven't run into that. one of the two bikes is always better and its not always the lighter one. especially when you throw an envelope in there and are trying to ride on the edge of it.

also.. to note, what goes up must come down.
don't get me wrong.. i love my light bike... its just not the one i go crazy on.
and i hate to say it.. but my climbing really lives and dies around my body weight (when were talking a pound of bike or a pound of body, i'll take body).

i shoot for light... but at 15 or 16 its relative unless were talking three huge climbs and a finish line this is silly. now if were talking 12lbs... ok there's a big diff...

[Ahneida Ride]

There is theory and then there is reality ...

I ride in upstate NY and VT. The roads and climate are unpredictable.

Thus I ride with Bomb proof wheels. CXP 4 cross mated to White Ind
Racer X Hubs. I can hit a pothole and just keep going.
Yup .... definitely extra weight .. and yes I have seen other wheels
have busted spoke issues.

The I ride with two full Stainless water bottles.
The Carradice Zip bag contains a flat repair kit in a zip lock bag,
a banana, wallet, glass case, car keys, small Topeak took kit, and
perhaps a rain jacket tucked away in the cover for my Brooks Saddle.

In addition ..... I have a Zefal pump and a DiNotte front amber running
light and a rear DiNotte tail light (includes two battery packs)

For me a extra pound on the frame is insignificant.

Now if were Racing .... well evey oz. counts .....

For reality riding, I have trouble understanding the weight obsession.

[gman]

I go just as slow on my 18 pound Serotta Colorado AL as I do on my 26 pound Lemond L'Alpe Duez steel with fenders, rack and overbuilt wheels and fat tires.

I notice that I work a bit harder climbing on the LeMond, but I am no climber anyway and I am sure that there is some difference, though I believe it to be negligible.

But then again, at my size this shouldn't be a surprise to anyone - 6'2" and 240 pounds.

I told my wife that in my next life I want to come back 5'10" and 150, but with the same size lungs I have now.

[WadePatton]

There is theory and then there is reality ...

... For reality riding, I have trouble understanding the weight obsession.
Reality is that there are a lot of folks who'd be much happier on touring rigs, but have "racer" rigs and ww thinking--light is sexy and sells w/ort reality.

I reality race...and if I were to mess around and win one or two, a lot of folks would be flabbergasted by my lead sled. Fast is as fast does. :banana:

[Tobias]

This assumes that the rider will put out the exact same amount of power on either bike--and will reduce gearing or cadence on the heavier bike. I just don't buy the time analysis. I would buy an energy expenditure analysis, but I find too many variables to swallow the time analysis. atwoWade, that's quite funny, actually. Energy and time analysis must give you the same results if you assume the rider puts out the same amount of power. You are talking about the same exact thing when limiting the comparison to a steep climb at very slow speed as I did. That's the best case scenario. On flats or downhills the difference is much much less.

You can also simplify the comparison by saying that if the climb is very steep and therefore very slow to the point where differences in aerodynamics is insignificant, then time or speed can also be compared by distance. In this case with a 150 pound rider so the totals are 165 and 166.5 pounds respectively, the heavier bike will go about 165 feet for every 166.5 the lighter bike travels. For every football field of distance climbed on a very steep grade, the bike’s lighter weight will make the rider pull ahead by about one wheel of difference.

Regarding gearing, think about the implication on speed differences. We are talking about climbing no more than 1 percent slower due solely to the weight difference. That means that if the rider stays in the same gear he will have a cadence of no more than about 1 RPM different -- and all studies puts that within an insignificant range. It’s like comparing 90 RPM and 90.9 RPM. And we don’t know nor can we know which of those two cadences is actually better for a particular rider; may make it incrementally better or worse.

IMO it is reasonable to assume "everything else being equal" when discussing an issue as raised in the original post, which addresses the question of weight. Unless of course the weight difference makes obvious other changes which must be taken into account (like gearing); but in this case it doesn't. One percent is too little to worry about.

[trymorecowbell]

One percent is too little to worry about.

1% is 1%. Whether it matters depends on one's goals.

Since the benefit of reducing bike/rider weight is linear at what percent should one start to worry??

[Ginger]

Hmmmm

Over time I can say that just rolling along Michigan flats on various bikes I notice a 10lb weight difference in bikes by how I feel at the end of a century. I don't really notice 5lbs or less difference.

On flats and up hills, I do however notice a difference if I'm riding my standard open pros, or my campy neutron tubular wheels. Lighter wheels feel faster to me.

[swoop]

ONE METRIC IN ISOLATION FROM THE GESTALT HAS NO FREAKING MEANING.


work with me. its not even a discussion worth having.

[capybaras]

quit eating

[Ginger]

ONE METRIC IN ISOLATION FROM THE GESTALT HAS NO FREAKING MEANING.


work with me. its not even a discussion worth having.


You think we do this to keep you happy?

[capybaras]

You think we do this to keep you happy?

yes?

[swoop]

You think we do this to keep you happy?

please regulate swoop's affective state by thinking of the bike as a complex set of variables all in relationship to each other and none separate from the rider.

[capybaras]

please regulate swoop's affective state by thinking of the bike as a complex set of variables all in relationship to each other and none separate from the rider.

what are you smoking? :banana:

[trymorecowbell]

its not even a discussion worth having.

Then don't :rolleyes:

[saab2000]

or my campy neutron tubular wheels. Lighter wheels feel faster to me.

They are prolly a bit lighter, but are also stiffer.

I noticed it the first time I rode with my Nucleons. That's how wheels should feel.

I still say that losing 2 lbs of fat off the ol' beer belly will have more impact than losing 5 lbs off my bike.

[capybaras]

Then don't :rolleyes:

maybe it would be better with more cowbell :banana: :banana:

also it helps if you quit eating

[Tobias]

1% is 1%. Whether it matters depends on one's goals.You appear to be taking words out of context.

I referred to one percent difference in weight not making enough difference to trigger secondary effects like throwing the rider into an inefficient pedaling cadence; which is what I was responding to.

Up to 1 percent improvement in speed is nothing to dismiss, but for most of us whether we climb a steep grade at 8 MPH or 8.08 MPH isn’t as big a deal as we imagine a 1-1/2-pound lighter bike makes.


Since the benefit of reducing bike/rider weight is linear at what percent should one start to worry??You are correct. When climbing steep grades at low speeds differences in aerodynamic forces are very small – insignificantly small – so performance benefits can be estimated as linear to weight differences. Those who accept that principle should be able to do rough estimates in their heads.

[Tobias]

ONE METRIC IN ISOLATION FROM THE GESTALT HAS NO FREAKING MEANING.


work with me. its not even a discussion worth having.Unless it was about fit, in which case it would be important to you. :rolleyes:

[Sisyphe Dol]

When climbing steep grades at low speeds differences in aerodynamic forces are very small – insignificantly small – so performance benefits can be estimated as linear to weight differences. Those who accept that principle should be able to do rough estimates in their heads.

The key reasoning to the above estimate is very slow climbing speed, so ignorable aerodynamic drag differences.

If you can climb not so slowly, or on relatively not steep hill, weight differences can not work as expected. (I don't know the exact numbers, but you can guess...)

So, only on very severe cases (very steep hill climbing), lighter bike will work as expected.

(So, even with 10% weight difference can't make you climb 10% faster, maybe for 5~6% fast. :rolleyes: )

[cloudguy]

Up to 1 percent improvement in speed is nothing to dismiss, but for most of us whether we climb a steep grade at 8 MPH or 8.08 MPH isn’t as big a deal as we imagine a 1-1/2-pound lighter bike makes.

You are correct. When climbing steep grades at low speeds differences in aerodynamic forces are very small – insignificantly small – so performance benefits can be estimated as linear to weight differences. Those who accept that principle should be able to do rough estimates in their heads.

I think if everyone lived in Boulder (or some other steep hilly place), there would be no arguments with the math. I've definitely seen and fealt the benefits of 1-2 lb weight reductions on the bike (which is a constant over time as opposed to body weight), especially on the longer 5000 ft climbs around here lasting ~ 1 hr.

Arguments against this seem to be like those against Galileo's
heliocentric model of the solar system.

[swoop]

I think if everyone lived in Boulder (or some other steep hilly place), there would be no arguments with the math. I've definitely seen and fealt the benefits of 1-2 lb weight reductions on the bike (which is a constant over time as opposed to body weight), especially on the longer 5000 ft climbs around here lasting ~ 1 hr.

Arguments against this seem to be like those against Galileo's
heliocentric model of the solar system.


why is my tt bike heavier than my road bike? it can't go faster if its heavier.