The Case of the Laid Back Lady

May 13, 2013

Last week I sent out a problem to several hundred bike fitters. It was a theoretical conundrum requiring a solution. I invited these fitters to solve the problem and I thought Slowtwitchers might like to know how some of the cleverer, more knowledgeable fitters in North America operate. The problem is below, and notable comments offered by some of these all star fitters are just below that.

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Woman comes in, wants to be fit for a road race bike, she's 5'5" tall, saddle height of 63cm (BB to saddle top, midway between tip and tail). 165mm cranks.

You give her input on the fit, she's aboard a fit bike that measures X/Y to the handlebar clamp, alternately she's on a fit bike from which you derive an X/Y to that spot via a Serotta X/Y tool or similar.

She prefers a position, if left to her own devices, that yields a bike with a seat angle of 73.5°, nose of her Specialized Romin saddle is 60mm behind the BB, and her handlebar clamp measures 550mm above the BB and 395mm in front of it.

She will face several problems with these results. Name the problems you can think of, and why. Then list any solutions or possible solutions, or clues to solutions, and techniques yielding solutions. Special credit given to those who devise solutions to this problem that include the rider agreeing or choosing the solutions you have in mind of her own accord, rather than our imposing changes in fit metrics on her.

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Several fitters figured out right away the crux of the problem. “The handlebar reach was set too short at 395mm and the saddle setback of -60mm should have never been an option,” wrote Todd Carver, lead fitter at Retul University. “60mm of setback is too much,” said Dave Luscan. “That's the 1st thing that jumps out at me.”

Rachel Wills of Moment Cycle Sport got downright mathematical and ferreted out sloppiness in my question: “I do not believe a -6 setback with 63 saddle height equate to a 73.5 degree seat tube angle. It's closer to 72.” Spot on, Rachel. When I wrote out the question I had certain answers I hoped to elicit, and my intent was simply to state that the saddle is farther back than it ought to be – but not horribly far back – and that the result was a pull-back of the cockpit to an untenable degree. My statement that the bike resulting from her fit was 73.5 degrees was off-the-cuff and sloppy, and Rachel figured that out.

Rachel's comment made me go back and actually calculate, and she was precisely right. A bike built for this saddle offset, if spec'd with a seatpost setback at 1.5cm, would require a bike with a 72-degree seat angle. I think it’s notable that Rachel is this good, considering she’s not the lead fitter at Moment Cycle Sport. This says a lot about the technical expertise at this San Diego shop.

There were several answers that I was looking for in order to solve this problem. Only one fitter touched on one of the answers I hoped to elicit, and not surprisingly it came from Jon Blyer: “Make sure she is using a compact handlebar, if not, I might be able to squeeze an extra 10 or 20mm of handlebar reach out of her without actually changing her position when she is riding the hoods.” I left out any mention of handlebar reach in the hope someone would catch this, and Jon did. In fact, if the fitter chose a bar with a bar reach of 90mm, just changing out the bar for one with a reach of 70mm (Profile Design and Zipp, to name two, make these bars) means you can draw a cockpit back to a proper length without making any other changes. Better yet would be to spec this bar geometry for the fit since you know this is likely to be an issue for any rider 5'4".

Jon also astutely offered, “I would experiment with shortening the cranks beyond 165 to help the toe overlap problem,” and demonstrated some acumen in how to design a custom with a short cockpit that will handle well, contacting, “Guru about drawing up a custom frame for her with something like a 71 degree head angle and a 50 rake fork.” Jon’s thinking here is that the shallow head angle plus significant fork rake keeps the bike’s trail in line while granting the bike sufficient front/center so as to sidestep a shoe overlap problem.

Rob Pinazza of Guru Cycles replied back with this lady’s custom geometry. If I might paraphrase what I think Rob would or could say, it might be: You fitters have a responsibility to return back to us sound fit coordinates. But often those coordinates to not suggest a straightforward solution, and a custom geometry is that straightforward solution.

A couple of fitters — including Paul Himmelman — correctly noted that a Pinarello Dogma makes a bike that would, on paper, fit a very short cockpit, and that both Cervelo (R3) and Cannondale (Supersix) offer elegant solutions to short cockpit problems. Brendan Poh from Cycle Craft mentioned all three of these bikes, though it should be noted that Cervelo, Felt and Specialized all make their women’s bikes using that head angle and fork technique that Jon Blyer mentioned, while Pinarello does not (meaning the Dogma will offer a short cockpit, but, will the bike handle as well as it might, with only one rake available for an entire size run?).

There were two techniques I was hoping might be offered during the bike fit session that no one mentioned, and they are, first, increasing the effort level required of the subject during the fit. The problem described above is a common one, because bikes built for those of shorter stature are typically overlong in their geometries because of the shoe overlap problems that attend small bikes built around the 700c wheel. If a subject sits where he or she wants on a small bike like this, the cockpit aren’t long enough – the riders feel too stretched out during a fit session. But they feel less stretched out once they are made to pedal at race effort and race cadence.

The second solution is a bit unfair to mention, because it requires tooling and a technique almost no fit studio has. The easiest way to uncover a cockpit too short is to make that rider climb a 7, 8 or 9 percent grade while out of the saddle. If handlebars are drawn too far back toward the bottom bracket, this problem will become apparent to the rider after 1 or 2 pedal strokes out of the saddle up a grade. Several of the fit bikes in my studio feature incliners but I had to built custom tables or incliners. Fit bikes aren’t yet built with these.

I’ll be sending out a couple of tough problems every month, and reporting back to Slowtwitchers who had the moxy and talent to ferret out solutions. For this first problem, chapeau to Todd Carver and Rachel Wills, who not only knew what to do with this fictitious lady, but found an error in the construction of the problem. To Todd and Rachel: you two were better at solving the problem than I was in designing it. Jon Blyer was his normal astute self.

Finally, Todd Carver wrote, “the saddle setback of -60mm should have never been an option initially,” and this speaks to a question of protocol, to wit, how much input and leeway should a subject be given during the fit? At some point perhaps we’ll speak to that in articles like this, but, the point I’m hoping to make in sharing this exercise with readers is that in an industry where every town has at least one self-proclaimed Aristotle of bike fit, there actually is a cohort of professional fitters who know their stuff and have the moxy and skill to demonstrate it.

The image accompanying this article features Kim, a customer an Now Bikes in St. Paul, MN, on a Guru Photon custom built for her using some of the design and spec techniques described above.

The fitters contributing to the solving of “The Case of the Laid Back Lady” are:

Paul Himmelman of Now Bikes in the Twin Cities.
Brendan Po of Cycle Craft (3 stores in northern NJ).
Jon Blyer of Acme Bicycle Co. in Brooklyn.
Rachel Wills of Moment Cycle Sport in San Diego.
Dave Luscan of Central Virginia Endurance in Richmond.
Rob Pinazza of Guru Cycles home of the Photon Series and – this is new – complete bikes.
Todd Carver of Retul and Retul University.