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Old 07-28-13, 06:24 AM   #1
vhj
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How to design a frame for a tall person??

I'm thinking of having a custom frame and forks built. I am planning to part the rest together myself. Actually, with the help of a friend.

I have done the online custom fit calculators and talked to a couple of popular frame builders. I have also talked to a few LBSs. Everyone’s opinions vary about the geometry of the frame. And most places want a good deal of money to do a REAL fit and geometry. I get that people need to make a living, BUT, I'm not sure whose opinion to take after getting varying ideas.

I am very tall and have proportionately VERY long legs. I am new to biking this year at age 58. I am riding a 64cm 1970's Raleigh and with the seat stem maxed out it's really not tall enough. The top tube is 60cm to flat bars extend forward, except my toes are very close to the front tire on turns. I also have 165 cranks and think I need longer cranks. I also wonder about the overall length of the frame hub to hub.

What is the best way to figure up a proper geometry drawing to take to a builder when I get so many opinions?
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Old 07-28-13, 08:20 AM   #2
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The voice you want to trust is an experienced builder who can also be your fitter that you hire by giving him a deposit. Not every builder is a fitter and not every builder has a lot of experience with tall riders. Most likely that should be someone close enough for you to drive to visit personally. At your age you are probably looking at a bicycle position with your handlebars up a little higher and closer than what would have been ideal when you were younger. And you aren't going to get younger to lower than down in the future (although getting fit through cycling may lower than some). It isn't just about picking a master brazer or welder. You can't expect professionals to take time to educate your ignorance for free to the level you wish if there is a chance you are going to eventually pay someone else.

There are various build and fit philosophies that can be in competition with each other. Don't expect an LBS employee to be quite in tune with custom builders because they need to sell what they have in stock and the biggest frames they have in stock are unlikely to be what fits you best at your age. So you if want to reduce the noise start by reducing the number of people that don't sell exactly what can fit you best. You next weed out builders who make stuff for the kind of riding you won't be doing or whose aesthetic with lugs or paint aren't to your taste. And then there is the cost you are willing to pay and the length of time you are willing to wait (which will rule out a lot of the very best). Probably when you do that you have reduced your list to only 2 or 3 and when you talk to them you will really connect to only one.

And yes you want longer cranks most likely something between 175 and 180.
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Old 07-28-13, 08:23 AM   #3
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I would take a look at zinn cycles as he does geometry specific to tall riders. The KHS Flite 747 is his design too. He has some interesting ideas. If I had the budget I might have gone that route.
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Old 07-28-13, 09:03 AM   #4
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Decide on the builder and let him/her design the frame based on your height/weight and the type of riding you intend to do; this is part of the package you get when you hire a builder. As a new cyclist there are a ton of design considerations you most likely dont have a clue about(nor should you be expected to), and each builder may have a slightly different viewpoint on design. Unless you're an architect/builder you wouldn't try to design/make working drawings of a house(maybe you would but not a great idea), the same applies to a bike build/design . IMO choosing a builder that has experience building very tall bikes(as in 67cm and up which sounds like you need) would be your best bet as there are considerations with a very tall frame that don't come up in a "normal" bike build. And stay away from LBS for frame fit, most are sadly lacking in information regarding this if you want more than a "ballpark" idea of fit.

Brian

Edit:


I see Doug posted when I was writing, you can't get better advice than his. Regarding Zinn, you will pay absolutely top $ from them, IMO the same quality is offered by many builders for a better $ value.
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Old 07-31-13, 01:50 AM   #5
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That is probably true, but unless they have a track record with tall people, you aren't getting your money's worth, as far as that is concerned. A person has to be pretty experienced, if they are average in height and weight, to do bikes out on the fine points of the Bell curve. They may well just be guessing, or getting recommendations from experienced suppliers. There are a lot of experienced people out there, just ask around.
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Old 07-31-13, 09:47 AM   #6
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you could check out Rivendell. they have some pretty big frame sizes and my all accounts are more than happy to talk to people, even if they have some strong opinions about what is and is not good in a bike

http://www.rivbike.com/product-p/f-hilsen.htm
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Old 07-31-13, 12:51 PM   #7
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Thanks, I'll check it out. And thanks for the other thoughts. I have a long way to go to make a decision...

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Old 07-31-13, 01:06 PM   #8
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We are too far away... we also specialize in building frames for taller riders and much of that comes from Arvon himself who is a big man who has been riding custom made frames since he raced in the 50's and then became a frame builder himself.

Consider what kind of riding you want to do because that will determine a great deal about what kind of bicycle you need... it sounds like your Raleigh is a road bike with steeper angles and tighter clearances so this explains the near case of toe overlap which is acceptable if you are racing or riding track.

Flexibility is also an issue and new riders and older riders tend to be less flexible... as a new rider you might also have issues knowing exactly what you want and need from a bike.

We have some very experienced customers who have sent us complete drawings and plans for their builds because they know exactly what they want and others who need a lot more time and help with working out the details.

Getting a professional fitting is a good idea... it will provide a lot of information for a potential builder to work with.

Most important is to work with a builder who is local and provide a lot of one to one communication as a custom bicycle is a significant investment and something you may be riding for a very long time.
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Old 07-31-13, 09:00 PM   #9
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I would take a look at zinn cycles as he does geometry specific to tall riders. The KHS Flite 747 is his design too. He has some interesting ideas. If I had the budget I might have gone that route.
Despite his height and experience building and riding big frames, I would most emphatically NOT buy a Zinn or follow his advice on frame geometry. He has an obsession with 73 degree seat angles, and I'm definitely not a fan of the "shopping cart" steering geometry he advocates. I've been riding for 50+ years (learned at 8 and never stopped), raced USCF for 15, commuted for 30+ now, and rando'ed for probably 10 years off and on. Oh, and I ride 63-65 cm frames. The two best-handling bikes I've ever ridden are thoroughly conventional: Eddy Merckx Ti AX and Eisentraut Rainbow. Both had quite slack seat angles (71.5 and 72 degrees respectively), moderate top tube lengths (58.5 and 59 cm) and wheelbases on the short side. In fact, the 'Traut had the shortest wheelbase of any road bike I've ever ridden at 38.5" (98.5cm?), had telepathic steering (always did exactly what I wanted it to) and was rock-solid at speeds up to 50 mph (never went any faster). Oh, and no toe overlap with 700x25c tires and 175mm cranks. Eddy's on the tall side, but AFAIK, Albert's of medium height. The key, I think, is to get advice from knowledgeable, experienced riders of your height. And hopefully with similar riding style and expectations.

And don't expect to come up with a geometry, take it to a builder and have him (or her!) braze it up for you. Any builder worth the title will know far more about designing and specifying a frame than you do. Talk to other tall riders, get their recommendations, and trust your builder.


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Old 07-31-13, 10:18 PM   #10
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Originally Posted by rando_couche View Post
Despite his height and experience building and riding big frames, I would most emphatically NOT buy a Zinn or follow his advice on frame geometry. He has an obsession with 73 degree seat angles, and I'm definitely not a fan of the "shopping cart" steering geometry he advocates. I've been riding for 50+ years (learned at 8 and never stopped), raced USCF for 15, commuted for 30+ now, and rando'ed for probably 10 years off and on. Oh, and I ride 63-65 cm frames. The two best-handling bikes I've ever ridden are thoroughly conventional: Eddy Merckx Ti AX and Eisentraut Rainbow. Both had quite slack seat angles (71.5 and 72 degrees respectively), moderate top tube lengths (58.5 and 59 cm) and wheelbases on the short side. In fact, the 'Traut had the shortest wheelbase of any road bike I've ever ridden at 38.5" (98.5cm?), had telepathic steering (always did exactly what I wanted it to) and was rock-solid at speeds up to 50 mph (never went any faster). Oh, and no toe overlap with 700x25c tires and 175mm cranks. Eddy's on the tall side, but AFAIK, Albert's of medium height. The key, I think, is to get advice from knowledgeable, experienced riders of your height. And hopefully with similar riding style and expectations.

And don't expect to come up with a geometry, take it to a builder and have him (or her!) braze it up for you. Any builder worth the title will know far more about designing and specifying a frame than you do. Talk to other tall riders, get their recommendations, and trust your builder.


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To add to the reference of Albert Eisentraut and tall riders.

When i took his building class (the last East Coast one if I'm right) he described his rider size and frame geometry principles. Al said that as the rider's size increased his need to be placed further behind the BB increased. My notes of the class specifically mention knee over pedal as the goal. He also said that as the rider's mass (weight, inertia you pick I'm no engineer) goes up the need for steering stability goes down. What these two aspects usually mean is with a taller/bigger rider the seat tube angle slackens and the head angle increases. This keeps the wheelbase short, the top tube long and a 55%/45% weight balance rear/front. Of course these rules are not cast in steel...

I have a lot of experience with small sized frames and only have been involved with a couple of frames that were very large (72 and 74cm). I have followed the principles that Al taught me, more or less, and have had good success. Andy.
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Old 08-01-13, 10:26 AM   #11
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I appreciate the thoughts. It seems like the more I know the more I know I don't know.
I'll ask around the LBS's here for tall riders and framebuilders.

Last edited by vhj; 08-01-13 at 10:27 AM. Reason: wanted to go advanced
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Old 08-01-13, 10:37 AM   #12
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To add to the reference of Albert Eisentraut and tall riders.

Al said that as the rider's size increased his need to be placed further behind the BB increased. ......with a taller/bigger rider the seat tube angle slackens and the head angle increases.
Interesting Andy. Question: On a tall frame(lets say 67cm and up) as the seat angle slackens the rider is put farther back with respect to the rear axle, how does this not tend to make the bike a "wheelie friendly" design, especially while climbing seated? It would seem that the cs must be lengthened to compensate for this aspect of the design which in turn lengthens the wb(which is not a bad thing), right? Having a steep ht angle helps keep the tt long and the front center and wb length short(er), but IMO chain stay length is a very important factor in tall(ok, really tall) frame design.

thanks,

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Old 08-01-13, 11:46 AM   #13
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I appreciate the thoughts. It seems like the more I know the more I know I don't know.
I'll ask around the LBS's here for tall riders and framebuilders.
If they are still in business Cycles De'ORO over in Greensboro is/was into custom frames. I haven't been there in 10 years so my info is pretty dated.

I'm a tall rider myself (64 cm road) My best advice is whom ever you chose as a frame builder make sure they have actually built tall frames and are not exclusive to lugs. I ride with a guy who has owned a 66cm ZINN for several years and loves it . What I like about it is the extra ~5 cm of head tube Zinn put above the top tube which leaves tons of stem height adjustment without stacking 4" of spacers and shims.. Zinn also made the head angle 71 degrees with the resulting longer fork rake which left ample room for my Bro's size 14 feet and 185 mm cranks. When I built my last road frame I almost copied his, except I had to deal with the limitation of lugs so I couldn't get as much head tube height as his bike.

BTW, Don't get yourself hung up on tubing brands, many of the popular tube sets likely won't have tubes long enough or thick enough for some of the tube lengths you will need (I used a mix of 3 different brands)
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Old 08-01-13, 03:11 PM   #14
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Brian- Good question. My thoughts are that the chain stay length should potentially grow with the frame size to keep the fore/aft balance in a nice range. But one of the problems with designing bikes for the fringes of the bell curve is that these people want to be just like the masses that they see all the time, ride with, read about in publications. I have done a lot (for my meager volume anyway) of small bikes, as well as sold Terrys for years. Many small riders are hesitant to go to smaller wheels because they listen to those who don't need to use small wheels. So, back to the CS question, if "all" "good" bikes (those that are written about) have a CS length of between 40.5 and 42cm then any bike with a longer CS is not a "good" bike. (In the eyes of many who think they lead when they actually only follow).

This willingness to drift from the norm is part of designing for the fringes. The customer needs to have the confidence in the builder to accept the design, or they will find a builder who matched their preconcieved ideas. Velonomad's comments are spot on about construction. The diameters, wall thicknesses and tube lengths will not be the norm and might prove hard to get. The angles of the joints will be outside the range of lugs and shells often.

In an ideal world the tire/wheel size would also grow with the rider size. So 5' tall riders might use 571/650C, 5' 10" might be 622/700C, and 6' 6" might be 674/755C (yes, that last one is made up.). Andy.
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Old 08-04-13, 12:35 PM   #15
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Despite his height and experience building and riding big frames, I would most emphatically NOT buy a Zinn or follow his advice on frame geometry. He has an obsession with 73 degree seat angles, and I'm definitely not a fan of the "shopping cart" steering geometry he advocates.
I have a friend who just bought a Zinn/KHS bike and he really likes it. He'd been riding a 65cm Cannondale for a long time but likes the ride of the KHS better. He also likes the long cranks and he saved enough money over a custom build to add on some really nice wheels.




Here's another tall guy who I talked to and is happy with his choice.

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Old 08-05-13, 05:28 AM   #16
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Zinn or follow his advice on frame geometry. He has an obsession with 73 degree seat angles, and I'm definitely not a fan of the "shopping cart" steering geometry he advocates.
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What do you mean by the shopping cart steering geometry?

I corresponded with Zinn's several weeks ago and his response was:

Due to your long legs, your frame would be the equivalent of a 73cm frame with a level top tube and standard industry crank length. However, as you can see on our site http://zinncycles.com/Zinn/index.php...es/dolomite-ti, in order to stiffen the bike and prevent the high-speed shimmy that plagues big riders and tall bikes, as well as to be more biomechanically efficient, I slope the top tube, drop it down at its intersection with the head tube, and raise the bottom bracket for a longer (proportional-length) crank, so the actual seat tube will be much shorter than 73cm.


You have relatively long lower legs relative to your thighs, so a bit steeper seat angle is required than normal.
As your legs are so long relative to your height, your top tube is not super long--61cm with a 130mm stem (yes, it became shorter, because your leg length got longer in this set of measurements, and the arm and torso sternum to floor lengths did not change.


Your ideal crank length would be 215mm, which is 20.6% of your leg length. END QUOTE

These are my measurements in cm:
> Height 201.3
> Sternum to Floor 166
Shoulder To wrist 67
Crotch to floor 104.5
>Thigh Length 70.5
> Lower leg length 68.6

>shoe size 14
weight 215

Any thoughts concerning this? I was thinking of Titanium frame, but probably can afford a steel frame. I'm not looking for a racing bike, more of a comfort/endurance style. Need to climb the mountain roads where I live and would like to keep up with medium groups.
Thanks

Last edited by vhj; 08-05-13 at 09:34 AM. Reason: correcting info
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Old 08-06-13, 10:39 AM   #17
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Zinn can leave his seat angles at 73 deg because he is adjusting for your Knee-Over-Pedal position by making the cranks longer. The Zinn-rider I know has 210mm crankarms (not the 185's I thought)and he says he puts down some serious torque when he stomps on the pedals.

IIRC, on a 60cm seat tube each degree in seat tube angle moves the top of the seat tube about 1 cm. If you consider the difference between say a 175mm crank and a 215mm that could be almost like having a 70 degree seat tube angle

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Old 08-06-13, 10:21 PM   #18
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Zinn can leave his seat angles at 73 deg because he is adjusting for your Knee-Over-Pedal position by making the cranks longer. The Zinn-rider I know has 210mm crankarms (not the 185's I thought)and he says he puts down some serious torque when he stomps on the pedals.
Seems like I recently read where the knee over pedal fit(a long tradition) is a starting point as the biomechanical benefit of KOP is limited at best. Any one have input on the subject? I'll try to find the article.

That the longer cranks produces more torque is also questionable. Pretty sure I can find that study, done at Utah State(IRRC), probably some of you have read it, something about the gear ratios making the crank length insignificant.

thanks, always looking to expand my knowledge,

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Old 08-06-13, 10:30 PM   #19
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In my opinion you have two reasonable options.

The first is to find a builder you trust and then place yourself entirely at his mercy. Take what he recommends and hope that it is right for you - and chances are that it will be. Just don't fall into the trap of taking his advice and then modifying it, because then you will never be quite sure that you made the right decision, and the builder will respond to problems with "I told you to do it my way!"

The second is to gain enough experience on your own to know what you want. This is arguably the better solution, but requires you to put off your custom dreams for now and continue riding off-the-shelf bikes until you've got things sorted to your own satisfaction.

FWIW, I've been seeing this frame on Ebay for pretty much forever. It's a great frame and huge, and the price has come down to giveaway levels, so maybe it can help with your learning process. (I have no connection to the seller, but am kind of sick of seeing it come up...)
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Old 08-06-13, 10:37 PM   #20
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Seems like I recently read where the knee over pedal fit(a long tradition) is a starting point as the biomechanical benefit of KOP is limited at best. Any one have input on the subject? I'll try to find the article.

That the longer cranks produces more torque is also questionable. Pretty sure I can find that study, done at Utah State(IRRC), probably some of you have read it, something about the gear ratios making the crank length insignificant.

thanks, always looking to expand my knowledge,

Brian
IMO KOPS is rarely wrong, but not always completely right. I personally prefer to be slightly behind the spindle. It just feels right to me. Other people prefer to be right over the top, and some prefer to be far behind it. A very few people even like to be in front - I think they're wrong, except when they're faster than me.

Short version: KOPS is a fine starting place. For many people it's a fine ending place too. It's just not the word of god, so if you feel like moving a bit from there you don't have to worry about sudden bolts of lightning or anything.
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Old 08-07-13, 08:46 AM   #21
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Seems like I recently read where the knee over pedal fit(a long tradition) is a starting point as the biomechanical benefit of KOP is limited at best. Any one have input on the subject? I'll try to find the article.

That the longer cranks produces more torque is also questionable. Pretty sure I can find that study, done at Utah State(IRRC), probably some of you have read it, something about the gear ratios making the crank length insignificant.

thanks, always looking to expand my knowledge,

Brian
Bio-mechanics are not my specialty so I'm in no position to refute either claim. I have to rely on my own experience as a rider and observer. I would agree that KOPS is a starting point not necessarily an end point. For me I am most comfortable with knee square over the pedal. I know others who like to an be inch or so forward of the pedal center

As for torque, longer moment arm/ lever will equal more torque for a given effort. What I had not considered until thinking about it last night is that us long legged riders probably don't spin as efficiently as shorter smaller riders. Therefore turning a larger circle at a slower speed may take better advantage of our mechanics ?
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Old 08-15-13, 05:35 AM   #22
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Proportional crank length is the key to making very big frames, ie beyond XL size.
If crank size goes up with rider size up to 175mm, why does it stop there? Only because no-one makes longer cranks. If you can find a place that makes them, get them.
Once you have long cranks, you can design the bike, using a high BB for cornering clearance, a long centre-front space for toe-clip clearance. With your 3:00 at the end of a long crank, you don't need the saddle so far back from BB for KOPS position, so a more normal angle will do the job.
KOPS , as suggested is a good starting point, not an end point of fitting, but a v tall rider on v short cranks is not well served by any fitting process.
Long cranks are long levers and permit the generation of high torque at low revs. The transmission converts this to wheel speed BUT the torque has to be resisted by the frame. Big riders are also heavier and stronger. Long cranks increase toque on the frame. Frame tubes need to be much, much fatter.
The std practice is for small frames to be stiffer and big frames to be bendier (deflection per unit force), the inverse of the actual requirement. If you cant find fat tubes in steel, try another material.
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Old 08-24-13, 05:30 PM   #23
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Longer crank = more leverage. I think you might be on to something with efficiency of shorter legs. I have a picture if Bill Walton's custom bike built by the guy who shares/shared? A shop with Joe Bell. I'll see if I can find it & post it here.
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Old 08-25-13, 04:26 AM   #24
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Bill Walton bicycle. I couldn't remember the name of the builder, it's right on the bike...Holland. I don't know much about his bikes, so its just another name for you to throw into your research bag.

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