The Knowledge 1.0 - Bike Frame Design Process

I get some contact points, and find a way to connect those dots while also having some frame measurements that resonate
with them atmo. In this case, whatever seat tube, setback, and top tube numbers allow me to accommodate the rider over
and between the wheels are the ones I set the fixture to. The angles, whatever they are, are selected so that the position
of the rider as well as the linear measurements control the design.



http://farm9.staticflickr.com/8399/8...cf4bff62_c.jpg

http://farm9.staticflickr.com/8126/8...7fd17045_c.jpg

Thanks a ton for posting this Richard. As a life long cyclist, bike mechanic/shop guy, and product designer I'm always asking the questions that will help me understand both how things work and how to make them better for the end user. My whole career has revolved around outdoor athletes, the gear they use and the ergonomics that allow them to work well. I've been waiting for a post on frame design for a long time but have been hesitant to ask about it because I didn't want to come across as trying to extract secrets... I'm really looking forward to your insight and to learn more!

Gotta ask, what's the dollar bill for?

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Originally Posted by bryand

I'm really looking forward to your insight and to learn more!

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Well I am one of those, "The frame design is a means to an end" kinda' guys, the end being the rider attaining a decent position on a bicycle that works atmo. And if the rider simply cannot accept a decent position on a road-ish bicycle, I don't bend the design to accommodate him; that would compromise the characteristics of the bicycle. I either select the design I think he should have OR I suggest more time on a bicycle, at the gym, or away from the dinner table.

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Originally Posted by -HvA-

Gotta ask, what's the dollar bill for?

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When I do the almost-final set ups, I often slip it under one section of the top tube as a shim in order to better mate the front miter with the head tube it has to play nicely with. Then, I pin it all. And then, I reassemble all of it withOUT the V block under the top tube. The pins hold the pipe plumb inside the set lug and head lug, with no stress added by the clamp, now removed.

cool.
frame is within a few mms of my size!

I agree completely. Whether it's a one-off product like your frames or a mass produced product that I design, I feel that it's essential to be thorough in the research stage, ask the right questions, and after putting all the pieces together the best solution to the problem comes together.

Based on that, there are obvious simple starting points with saddle height, etc. You seem to have highlighted some dimensions such as 15cm st/tt setback. At the risk of being presumptuous, I assume these are some basics you rely on to get the rider "over and between the wheels"? This would then lead me to believe that you try to minimize the variables of adjustable saddle/rail setback or stem length. Could you please elaborate more on that?

Thanks again!

The frame size is chosen so that the extended saddle height and seat post showing look like an elegant solution. The frame setback is shosen so that I can place the saddle in the right place, horizontally, using a traditional seatpost and have the rails centered. The reach is concluded by choosing 1) a certain top tube range, and 2) a certain front center range and, 3) a stem length appropriate for the bicycle size. The head angle telescopes the stem up and out. I change it by the minute in order to fine tune the reach, but only after the pipe and the F/C are dialed in.

For most folks, the depressed area of the saddle is the natural balancing and resting place. If the sight line of the seat tube doesn't intersect it, then the seat angle is either too steep or too shallow (measured as setback, and in mms). The ideal is to rearrange what the fellow has such that the depressed area is in plane with the seat tube.

Later -

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Originally Posted by bryand

I agree completely. Whether it's a one-off product like your frames or a mass produced product that I design, I feel that it's essential to be thorough in the research stage, ask the right questions, and after putting all the pieces together the best solution to the problem comes together.

Based on that, there are obvious simple starting points with saddle height, etc. You seem to have highlighted some dimensions such as 15cm st/tt setback. At the risk of being presumptuous, I assume these are some basics you rely on to get the rider "over and between the wheels"? This would then lead me to believe that you try to minimize the variables of adjustable saddle/rail setback or stem length. Could you please elaborate more on that?

Thanks again!

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That faux stem is priceless

BTW, how do you deal with the situation where you receive contact points that seem wrong ? Or do you always start from body dimensions ?

Front center is the one I am stuck a little on. Some of it would be determined by reach and fore aft weight balance but what else do you use to dial it in and hence decide on the fork offset. Style of bike ie road or CX? Using the picture above, with a 48 offset, would this end up with a slightly shallower head angle? From memory you ahve said in the past you probably wouldn't know the head angle of most of the frames you build and my thinking hear is if this is for CX then a slightly longer trail would be the norm. Trying no to over think it.

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Originally Posted by Lionel

BTW, how do you deal with the situation where you receive contact points that seem wrong ? Or do you always start from body dimensions ?

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I just tell the guy that the contact points seem wrong. And sometimes I explain that, were I to be indentured to what I see as wrong, the bicycle he wants me to make using this information will steer and descend like a shopping cart rather than a RS atmo. That's the best I can do in this situations. I almost never look at the body dims. Well, to be fair, inseam and foot length have a part in the equation.

Very cool, thank you for posting. I'm not a skilled mental imager - this helps to make things clear.

e-RICHIE, Post like these are the reason I hang out here.

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Originally Posted by e-RICHIE

I almost never look at the body dims. Well, to be fair, inseam and foot length have a part in the equation.

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Interesting. Knowing how you build (made to measure vs "custom") I had assumed you asked for body measurements and built the bike around those, but if I'm reading correctly, your customers supply contact points, and those *drive your design?

It's interesting to see your design philosophy (like not knowing/caring what some of the angles are) coming from a MTB background, where everyone seems to be soooo concerned with numbers. Seems like people think they can look at a geometry chart and know exactly how a bike will ride. When I review bikes I rarely look at the geometry charts until after I've been on the bike for a while, only thing I ever look at is effective top tube length to pick a size. I want to see how it rides without any preconceived ideas.

*I know you build the way you see fit, but there obviously has to be some starting point, even though you may make some adjustments.

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Originally Posted by dgaddis

Interesting. Knowing how you build (made to measure vs "custom") I had assumed you asked for body measurements and built the bike around those, but if I'm reading correctly, your customers supply contact points, and those *drive your design?

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I get/take all the measurements, but some are formalities, some are for the expanding reference building library in my cranium, and some are for checks and balances. At the end of the day, it's about sitting on a bicycle in an efficient position, and have that there bicycle work as intended.

Thanks Richard for this thread. It's also good to know that I'm not alone thinking that foot length have it's place in the equation.

Not to make things more complicated but does mass distribution is taken in account when you build a bike?

Thanks!

What is the general range you like to use for Front center on a road bike. Thanks for posting.

-Jim

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Originally Posted by Guillaume

It's also good to know that I'm not alone thinking that foot length have it's place in the equation.

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It totally does.
I had a 32" inseam, but a long reach as I had a 48 shoe.
Basque-o Wierd-o.
- Garro.

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Originally Posted by JimFrain

What is the general range you like to use for Front center on a road bike. Thanks for posting.

-Jim

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It's 58cm - 62cm depending on the commission atmo.