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Framebuilders Thinking about a custom frame? Lugged vs Fillet Brazed. Different Frame materials? Newvex or Pacenti Lugs? why get a custom Road, Mountain, or Track Frame? Got a question about framebuilding? Lets discuss framebuilding at it's finest.

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Old 01-22-11, 06:33 AM   #1
Road Fan
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Weight distribution f/r?

What should the f/r weight distribution be for a road or brevet bike? As in most of cycling there's a lot of opinion out there. Expert recommendations range from 50/50 to 40/60 front/rear. Where's the truth, or what are the issues?

For me, my Mondonico and 1984 Trek measure out to between 40 and 45 % front. My Peugeot UO-8 vintage beater has very long chainstays, and it's right about 46% front.

The biggest influences on weight distribution seem to be rider weight and the rider's position relative to the axles.
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Old 01-22-11, 06:08 PM   #2
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I should have known, this is going to be another one of those zero response questions.

How about this:

What is the ideal weight distribution to the wheels of a road bike?
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Old 01-22-11, 07:28 PM   #3
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I'll take a stab at a non-answer.............

There isn't one. At least there isn't a static one.

If you place a bike on scales, sit on it and then move your hands from the tops, to the hoods, and then to the drops you'll see the weight distribution vary dramatically. You can even see fairly large changes when lifting or lowering one's head.

I think you are right on - the actual distribution is much more a factor of the fit (saddle height, saddle fore/aft, stem length and bar drop) and the rider's build (riders with strong line-backer shoulders will have a much different weight dist. than a guy with the same height/arm/leg).

All that said I shoot for a static placement of about 60/40 to 55/45. Bikes in this general range are more likely to give good turn in and be stable at speed.

I hope that helps - like I said it's a bit of a non-answer.

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Old 01-23-11, 08:27 AM   #4
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It's a very helpful answer, Dave, it adds to my insight. You read my question in both of its guises, and between the lines. One matter was, is there a preferred value? And another was, does it extend to 50/50? On another list a member posted that a well-known builder set a target of 50/50.

So there isn't an ideal value, but a desired range.

What happens with a frame that's 50/50? Seems to me that without a very long chainstay (50cm?) the front end would have to be very upright and tight-clearanced. Possibly good for short-course racing, but I'd not want that for long-distance, especially if I have a panic stop when I'm hammered at the end of the day.
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Old 01-23-11, 12:45 PM   #5
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longer top tube makes the front wheel feel lighter.

Look at the standard geometries square around 55, 6 , 7
seat tube length and top tube lengths are nearly equal.
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Old 01-23-11, 02:55 PM   #6
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Quote:
Originally Posted by fietsbob View Post
longer top tube makes the front wheel feel lighter.

Look at the standard geometries square around 55, 6 , 7
seat tube length and top tube lengths are nearly equal.
Can you clarify your point regarding square frames? Seems to me front wheel position is function of seat tube angle, TT length, HT angle, and fork offset. Square frame is NOT all there is to it.
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Old 01-24-11, 03:16 PM   #7
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I can't answer this, but I do wonder how it is possible without reference to the rider's needs. Also, is weight distribution the governing condition. Let's say your ideal weight dist. required you to change handling, which one would rule. Also what category of rider are we dealing with, this is sorta just first question above. But for a lot of "road" bike uses if you aren't actually trying to win anything, realistically, you might as well be comfortable, which is why there are savants like Brandt, who does hundreds of thousands of miles, and high speed descents etc... yet just has them slap on the full length of the chain stay.
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Old 01-25-11, 09:54 AM   #8
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I agree, there is no one answer. I'm glad to have these partial answers, since they increase my insight.
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Old 01-25-11, 12:27 PM   #9
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The rule of thumb I've always heard is 45/55 (f/r), static, in your "most commonly used" position. For a rando bike that'd be on the tops, behind the hoods. For a track bike, in the drops. Road bike? On the hoods.

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Old 01-25-11, 12:29 PM   #10
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Quote:
Originally Posted by fietsbob View Post
longer top tube makes the front wheel feel lighter.
That's true only if nothing else differs. And I have yet to meet a respectable frame builder who would lengthen the top tube w/o changing anything else.

SP
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Old 01-25-11, 04:43 PM   #11
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Quote:
Originally Posted by bobbycorno View Post
The rule of thumb I've always heard is 45/55 (f/r), static, in your "most commonly used" position. For a rando bike that'd be on the tops, behind the hoods. For a track bike, in the drops. Road bike? On the hoods.

SP
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Pretty much my thinking, as well, based on what I'm reading here and common sense. On the more racy side, Dave Tesch designed for 50/50 when he could, to get even wheel loading at the cornering limit for his racing customers. He also treated all his customers as racing customers.

But that's not me.
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