weight distribution

[Dr. Doofus]

he, i, and the mouse were all pretty bored and jet lagged today, so we did the old scale-and-book trick to measure our weight distribution

how accurate is that old primitive standby? done it in shops, used to have two teammates who swore by it...but does that really give you a fair measure of weight distribution

and another thing...the doc and i have several frenchie and italiano books around the house that say 45/55...yet serotta designs around 60/40...fact or fiction...forget drugs, lets talk center of gravity....

[zap]

I've seen figures around 45%F/55%R myself in some domestic publications some years ago.

As long as everything is level, no reason why 1 scale shouldn't be accurate. Using two scales just speeds things up.

So what is your (not the mouse) weight distribution?

[PaulE]

but if the sum of the two weights equals the weight of you standing on the scale and holding the bike, I would think it's accurate.

[Dr. Doofus]

corsa -- 42.5/57.5

csi -- 44/56

moser -- 44/56


the moser and csi are 74 sta, 59 top, 73.5 hta, 43mm rake

the corsa is 74 sta 59 top, 73 hta, 43mm rake

[dirtdigger88]

are you talking distribution of the bike only or when the rider is on it. wouldn' that be more important?

Jason

[Dr. Doofus]

you gotta be on the thing or its meaningless...the corsa has less in front because it was set up on the trainer with more setback...something to fix...one book, one scale, one friend, you on the bike, and yer in business....

[Too Tall]

Learn something new everyday Doc....er teach'. Now learn me how to get my hooks set so my hands are relaxed in crits and the reach to my levers is close AND I have flat sections on top. I'm always fiddling.

[PsyDoc]

He has two interesting cycling articles on bike fit. The URL is: http://www.kevinlippert.com/

He states a rider should strive for "...the proper weight distribution of 50%-55% on the back tire and 45%-50% on the front tire, when still allowing the right positioning guidelines."

[Dr. Doofus]

that lippert guy is, well, kind of nuts.

from a biomechanical perspective, everything he says about joints and angles makes sense, but...and its a big but...it goes kind of haywire when he puts it all on a bike...his guy who rides a 59 would ride a 59x59 with a 74 seat tube (which is the docs bikes), with a 110 stem...sure, that would give 45/55, but it would also be long in the f-c and *most* riders would need a more relaxed STA to get the KOPS he raves about...forget that most euros (and he is talking racer fit, so the euro reference is appropriate) run 1-2cm behind...only a few with long leg/short femur builds would fit well on his 74-59-59, and they would be locked into KOPS...if you move the saddle back 1-2cm the weight will hang more like 40/60, so you're locked into what is basically a TT position with 5cm or so of setback, all for a guy with a saddle up around 80-81...in short, I and the mouse are glad lippert is not bike designer, cause even though the doc's bikes are somewhat "lippertesque," the doc has a love-hate relationship with them, and if stock bikes were laid out like this guy says, they'd suck

basic lesson # 234, repeated: anytime some north american bike "expert" says "no no no, the italians have it all wrong, you should design a bike *this* way" run like hell and give your money to somebody else.

[weisan]

Alrighty...time to call up the dead DOofUs's *dead* thread.

Where/What?
washer/dryer room, one small stool, one accurate scale, one telephone book, one spotter (my 5yr-old)...ok, maybe two... the 2 yr-old woke up in the middle of it and insist on helping ...what can I do??! :D

When?
This morning, 10 minutes ago...

Why?
Quest to find out why my lugged steel rides the way it does.

The Results: All positions on the hood.
Steel bike
Front-65 Rear:95 Total Weight: 160
Weight Distribution (F/R): 41/59

Carbon bike
Front-61.5 Rear:97.5 Total Weight: 159
Weight Distribution (F/R): 39/61

Ti bike
Front-61.5 Rear:99 Total Weight: 160.5
Weight Distribution (F/R): 38/62

Conclusion:
This all make sense. The lugged steel has the shortest TT of all three bikes but had the longest stem instead - 130mm.
Riding position places more weight up front. Both Carbon and Ti has a 110mm stem.

Subjective Judgement:
I am satisfied with my fit on all three bikes. They can do whatever - sprint, short/long distance riding, bad roads, climb, ride on the drops for prolonged period of time etc.
Those are my basic requirements for keeping a bike. Any bike that cannot satisfy the abovementioned requirements are sold, thrown out, get rid of, given away... :D

Handling-wise...the carbon bike mirrors almost exactly like the ti bike, which is logical since they have almost exact same setup. What stands out for the lugged steel is stability and balance. Both the Ti and Carbon bikes are within acceptable range (read "basic requirements") in those departments. But the lugged steel really **SHINES** when it comes to stability. If someone were to pay me a million bucks to descend down Mt. Washington and maintain speed above 50 mph, the lugged steel will be called into duty.

OK, fun out.
:D

weisan

[Dave]

Using a book or boards to level the bike is proper, but the rider must be sitting in an agressive riding position, with the hands in the drops, fingers in reach of the brake levers and the upper back horizontal.

If the ridier has his hands on the brake hoods, in a more relaxed riding position the weight on the front will be substantially less. This is not a problem, because aggressive cornering isn't done from this postion.

It's also tough to stay balanced without some help and even the slightest movement of the rider will cause most scales to waver by a couple of pounds, so extreme accuracy can be tough to achieve. If you're off by 2 pounds on an 80 pound front measurement, that's a 2.5% error.

60/40 would be a pretty light front end. Where did you get the idea that Serotta "designs" around 60/40 weight distribution? Since every rider is different, it would take a pretty sophisticated setup to guarantee a particular weight balance on a custom sized bike.

Riders who position the saddle far back will always have less weight on the front end, unless they have longer than normal chainstays, or a short front center. Sometimes there must be compromises. You can't always produce the desired weight balance, saddle position and stem length, even on a custom bike.

[flydhest]

Doof, I reckon I'm an anomaly, then. I ride a 60/60 frame with a 12 cm stem, 73.5 STA and am 2 or 3 cms behind KOPS. Now you are making me want to go home and measure weight distribution.

Of course, it's possible that what I wrote doesn't make sense.

that lippert guy is, well, kind of nuts.

from a biomechanical perspective, everything he says about joints and angles makes sense, but...and its a big but...it goes kind of haywire when he puts it all on a bike...his guy who rides a 59 would ride a 59x59 with a 74 seat tube (which is the docs bikes), with a 110 stem...sure, that would give 45/55, but it would also be long in the f-c and *most* riders would need a more relaxed STA to get the KOPS he raves about...forget that most euros (and he is talking racer fit, so the euro reference is appropriate) run 1-2cm behind...only a few with long leg/short femur builds would fit well on his 74-59-59, and they would be locked into KOPS...if you move the saddle back 1-2cm the weight will hang more like 40/60, so you're locked into what is basically a TT position with 5cm or so of setback, all for a guy with a saddle up around 80-81...in short, I and the mouse are glad lippert is not bike designer, cause even though the doc's bikes are somewhat "lippertesque," the doc has a love-hate relationship with them, and if stock bikes were laid out like this guy says, they'd suck

basic lesson # 234, repeated: anytime some north american bike "expert" says "no no no, the italians have it all wrong, you should design a bike *this* way" run like hell and give your money to somebody else.

[dirtdigger88]

I ride a 60/60 frame with a 12 cm stem


hmm. . . .just my size- sorry- had to beat dave t to the punch

Jason

[flydhest]

anytime you're here in DC, you have your choice of bikes to ride . . .

[zap]

You can use a trainer to hold the rear in place. The bike will pivot around the rear skewer. Somewhere in this forum I posted my results including weight change by moving my hand placement fore and aft by 1 cm.

I'd like to get some local formites to come to my "lab" and check their distribution. Then install a longer stem and take them for a spin.

Be a fun experiment. Anyone game.

TT, I know you figured it out, so you can help.

[weisan]

Dave-pal, GOOD POINT!

[Dave]

I've used a trainer to hold the bike while weighing the front, but then realized it might cause an error in the reading since most of the weight of rear wheel is not on the ground. What it will quickly show you is that a longer stem has very little effect on weight balance. It will also show you that torso angle has a big effect on the weight balance. Dropping your nose close to the stem can add 4-5 pounds.

I just weighed my two bikes (set level and free-standing) and came up with 45% on the front with one and 46% on the other. This is with the saddle about 2cm further forward than I used last year (but my knee is still behind the pedal). With average reach bars, I would only use a 110mm stem to poduce this weight balance. I have 120mm stems on the bikes, but I also have short reach Salso Poco bars that are 10-15mm shorter in reach than most bars. Obviously you don't need a 130-140 stem to have a substantial amount of weight on the front.

Taking the same measurement with the bikes held on a trainer, both bikes registered 1-2 pounds lighter on the front.

[zap]

Dave, you might be right, but I figured that the trainer is holding and suspending the rear wheel by the skewer, which is in line with the tire contact patch.

I was more concerned with having everything level and ensuring that the trainer wasn't tightened to much to restrict movement. Funny thing is, I now know where the level sections are in my house.

I too sit behind the pedal, roughly 3.5cm. I can't remember how much of a weight transfer there was when I shifted my hands fore/aft by 1 cm, but a 6 lbs swing rings a bell.

[Dave]

Just moving your hands forward, without lowering your torso should make almost no difference at all, particularly only 1cm. There's no way it would be anything close to 6 lbs. Perhaps 1/2 of a pound. If you saw that much of a change, then you were doing a lot more than moving your hands. Torso angle and saddle position are the the major things affecting the weight balance.

Also, you can tighten the trainer all you want, the bike should still pivot freely on the rear hub.

Mounting in a trainer does take the rear wheel out of the equation.