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Technical Q&A with Lennard Zinn - The tall man's dilemma
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A tall man’s dilemma
Dear Lennard,
As a tall rider (6-foot-5 and a 36-inch inseam), what recommendations do you have for selecting a road bike:
● Are there some manufacturers whose frames are better suited to the tall rider?
● As a Clydesdale (>200 lbs), is carbon worth the added cost?
● Are there services which can evaluate your body frame and make unbiased recommendations on a bike manufacturer that would probably best fit your physique?
Steve
Dear Steve,
I’m not sure if this is a trick question, but perhaps you are not aware that I’m your height and have been building custom frames, cranks and bikes for tall riders for 27 years (and off and on – currently on, big and tall cycling clothing, too). So I have devoted much of my life to answering your question.
First of all, I would want you to re-do that inseam measurement, because 36 inches is a very short inseam for a 6-foot-5-inch rider. Perhaps that is your pants inseam size, which runs about two inches shorter than the actual inseam measurement from crotch to floor in stocking feet; 38 inches is an average inseam for a 6-foot-5-inch rider.
Obviously, there are some manufacturers better suited to the tall rider, and I consider myself to be the one most ideally suited. Most of my customers are your height and taller, and I understand personally the problems and challenges a tall rider faces. You don’t specify if you’re looking for a road or mountain bike. On the mountain side, there are choices for XXL frames besides Zinn, like Ventana, Lenz, and maybe Turner and Niner.
I also think you will be faster, more comfortable, and happier with a longer crank (at least 180mm, but we often build cranks more like 200mm for riders your height. The frame really needs to be designed for the crank, for obvious clearance problems, however.
Carbon frames in general make no sense for a rider your size, because most of them are molded in one to three pieces. Given the expense of the molds, that investment is only undertaken for sizes that fit the large part of the bell curve of rider sizes. These frames are generally not big enough for you, and usually they would not be stiff or strong enough either, not having been designed for riders of your weight, particularly with your height. That said, you could get a custom carbon frame from a small custom carbon manufacturer who miters carbon tubes like metal tubes and wraps the joints with carbon. Calfee, Parlee, and Kirklee come to mind.
As for evaluating your body measurements to determine frame size, there are lots of fitting systems out there ranging from free to around $1,000. You can go to the Boulder Center for Sports Medicine for the gold standard fitting including X-rays and 3D analysis. Many bike shops have fitters certified by companies like SICI, Bike Fitting, Fit Kit, Wobble Naught, Bicycle Fitting, Tiemeyer Position Cycle, or www.bodyscanningcrm.com. Less expensively, you can use Wobble Naught’s online fitting system, or buy Bill Boston’s Personal Accufit software. I used to have a free fit calculator system on my zinncycles.com site into which you could plug three simple body measurements (the first three body measurements here) and get back suggested frame dimensions and crank length for road or mountain bikes.
However, we recently re-designed the site, and that and a cool price calculator page we had were lost in the shuffle. Hopefully we will be able to get it running again with this new site soon. But in the meantime, you can use the appendix of Zinn and the Art of Road Bike Maintenance or Zinn and the Art of Mountain Bike Maintenance, I explain taking these same three body measurements and how to do the calculations yourself to come up with frame dimensions to fit you.
Lennard
Bearing bad news
Dear Lennard,
I currently have an FSA k-force light compact crankset on my ‘cross bike (and my road bike too). I like the cranks, it’s the bottom bracket I am not too happy with. The non-drive side bearings went out on me after seven races (they were even uncharacteristically dry races).
Interestingly I know of at least three other riders with similar stories about the non-drive side of the MegaExo bottom bracket. I was able to clean most of the gunk out and repack them; but the only recovered so far. I just acquired a set of Enduro bearings, which have slightly larger balls to replace them with and I hope that will cure my ills.
If that does not work, I would really love to move to Chris King’s bottom bracket. If that part is half as good as their headsets I would be overjoyed. However when I asked King if their bottom bracket was compatible with FSA cranks, the reply was that the King bottom bracket is built to Shimano’s HollowTech II standard. If FSA cranks are built to that standard, then the bottom bracket will work. Given that FSA cranks are moderately popular, I was hoping for something a bit more definitive.
Can you tell me whether or not the FSA k-force light crank will work with a King bottom bracket?
LeRoi
Dear LeRoi,
Definitely the bearing diameter of both the Enduros and the Chris King will work, because you can run a Shimano Hollowtech II crank in an FSA MegaExo bottom bracket and vice versa. The spindle diameter in both cases is 24mm, and both use a 7mm thick bearing. However, your FSA K-Force Light crank has slightly less width from arm to arm. I know because the kit does not yet exist to fit one on a Trek Madone.
The Enduro bearings will not work, either, because those are 7mm bearings, not 6mm ones.
FSA’s K-Force Light (and its other carbon cranks) use a slightly narrower bottom bracket than FSA alloy cranks (which are similar to the Shimano Hollowtech II size) and incorporate a wave spring washer to allow better bearing preload.
See more on this below from Dae Oh of FSA’s tech department.
Lennard
Answer from FSA’s Dae Oh
The short answer; no, the FSA K-Force Light Rd. Crank is not compatible with a Chris King bottom bracket (made to Shimano compatible dimensions). Also, the K-Force Rd. crankset will not be compatible either.
The FSA BB8200 (meant for K-Force Light) uses a 6 mm width bearing. This allows us to make the bottom bracket outside to outside dimension more narrow providing room for a wave washer. The BB8000 (meant for K-Force) does indeed use a 7 mm width bearing, yet its design does not allow for use of a Chris King bottom bracket.
However our popular alloy cranksets, the Gossamer Rd. and the Energy Rd. is compatible with the Chris King bottom bracket (made to Shimano compatible dimensions). These cranks use BB6000, this BB's dimensions are compatible with Shimano.
Dae Oh
Full Speed Ahead
Technical writer Lennard Zinn is a frame builder (www.zinncycles.com), a former U.S. national team rider and author of numerous books on bikes and bike maintenance including the pair of successful maintenance guides "Zinn and the Art of Mountain Bike Maintenance" - now available also on DVD, and "Zinn and the Art of Road Bike Maintenance," as well as "Zinn and the Art of Triathlon Bikes" and "Zinn's Cycling Primer: Maintenance Tips and Skill Building for Cyclists."
Zinn's regular column is devoted to addressing readers' technical questions about bikes, their care and feeding and how we as riders can use them as comfortably and efficiently as possible. Readers can send brief technical questions directly to Zinn. Zinn's column appears here each Tuesday.
