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For the fit experts...

Road Cycling “It is by riding a bicycle that you learn the contours of a country best, since you have to sweat up the hills and coast down them. Thus you remember them as they actually are, while in a motor car only a high hill impresses you, and you have no such accurate remembrance of country you have driven through as you gain by riding a bicycle.” -- Ernest Hemingway

For the fit experts...

Old 12-21-06, 02:49 PM
  #1  
donm
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For the fit experts...

I recently had a fitting session and the recommended frame geometry they gave me is below. I just wanted to get a second opinion to check that the numbers are sensible. Any help is much appreciated!

Seat tube (c-c): 57cm
Top tube: 58.4cm
Head tube: 16.7cm
Stem: 12cm
Seatpost setback: 0cm
Head tube angle: 73.5
Seat tube angle: 73
BB drop: 7cm
Plumb line saddle nose to BB centre: 5.9cm
Drop (saddle top to top of stem): 6cm

Here are some of my body dimensions:

Height: 184.1cm
Inseam: 87.1cm
Sternal notch to floor: 152.7cm
Torso length (seated from top of seat to acromioclavicular joint): 69cm

Last edited by donm; 12-21-06 at 03:41 PM.
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Old 12-21-06, 03:23 PM
  #2  
AnthonyG
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What you have quoted is missing important information such as seat tube angle, effective seat tube angle or saddle setback from the Bottom Bracket. You could be put onto various different bikes based on that information that had differing geometry and different fit.

Regards, Anthony
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Old 12-21-06, 03:38 PM
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donm
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Originally Posted by AnthonyG
What you have quoted is missing important information such as seat tube angle, effective seat tube angle or saddle setback from the Bottom Bracket. You could be put onto various different bikes based on that information that had differing geometry and different fit.

Regards, Anthony
Sorry, I forgot to add in some of the other information I was given. I've added it above.
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Old 12-21-06, 04:19 PM
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I put your numbers into BikeCAD and came up with what your bike should look like.
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Old 12-21-06, 04:33 PM
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I am 6'2" with a 36" inseam. For your measurements, I would almost suggest going with a slightly shorter top tube. Like 57.5-58cm. Especially if you are already using a 120mm stem.

I use a 58cm top tube on my bikes, and with a 120mm stem, it's pushing my reach limit for long term comfortable riding. I would almost prefer 110's, or perhaps even a shorter top tube. That's just my experience.

Other than that, it looks pretty good.
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Old 12-21-06, 06:31 PM
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Originally Posted by ccdisce
I put your numbers into BikeCAD and came up with what your bike should look like.
Thanks, that looks really good. Appreciate you taking the time to do that!
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Old 12-21-06, 06:34 PM
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Originally Posted by Patriot
I am 6'2" with a 36" inseam. For your measurements, I would almost suggest going with a slightly shorter top tube. Like 57.5-58cm. Especially if you are already using a 120mm stem.

I use a 58cm top tube on my bikes, and with a 120mm stem, it's pushing my reach limit for long term comfortable riding. I would almost prefer 110's, or perhaps even a shorter top tube. That's just my experience.

Other than that, it looks pretty good.
I was wondering about that, actually, and I may in the end go with an 11cm stem. The thing is, I'm about a 1.5" shorter than you, and my inseam is also about 1.5" shorter, so my torso is probably around the same length. Depending on arm length, I guess we'd need roughly the same reach to the bar. So if I go with 11cm, that would give me near enough the same reach. Do you use a setback seatpost?
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Old 12-21-06, 08:04 PM
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Yes. Mine are setback about 1". Pretty standard.
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Old 12-21-06, 08:16 PM
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Are you being measured out for a custom? I only ask because 73.5 is an interesting head tube angle. Is it supposed to be a crit bike?
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Old 12-21-06, 08:23 PM
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Originally Posted by donm
I was wondering about that, actually, and I may in the end go with an 11cm stem. The thing is, I'm about a 1.5" shorter than you, and my inseam is also about 1.5" shorter, so my torso is probably around the same length. Depending on arm length, I guess we'd need roughly the same reach to the bar. So if I go with 11cm, that would give me near enough the same reach. Do you use a setback seatpost?
fwiw you should come up with the top tube length after the stem length, not the other way around

you should roll a 120mm at that size, so whatever top tube makes you comfortable with a 120mm stem is the length you need

also (since you're getting a custom bike) make sure you design it with a setback post in mind

personally I think your best bet is to find a stock geometry that works. even if you get a bike from seven, serotta, if, etc. geometry isn't just about being comfortable on the bike--it's also about handling and proper balance/weight distribution over the wheels. manufacturers put a LOT of thought into their stock geos. think of it this way, their (any manufacturer/builder) stock geo is their best version--try not to deviate to far from it. and custom isn't about mucking with geometry (except when absolutely necessary), it's about defining the ride based on your input re: things like stiffness, comfort, etc, what kind of braze-ons you want on the frame, how you want to paint, etc. too many people seem to think custom is about doing some diy geometry because your arms are 1cm longer than most people your size, or some other sillyness. stock geometry, even for custom builders and manufacturers, is their best version of their product.

good luck

Last edited by Serpico; 12-21-06 at 08:30 PM.
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Old 12-21-06, 08:29 PM
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Originally Posted by pinkrobe
Are you being measured out for a custom? I only ask because 73.5 is an interesting head tube angle. Is it supposed to be a crit bike?

Its not uncommon, 73/73.5 as he was quoted is the same angles of my Lemond.
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Old 12-21-06, 08:44 PM
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Originally Posted by Serpico
fwiw you should come up with the top tube length after the stem length, not the other way around

you should roll a 120mm at that size, so whatever top tube makes you comfortable with a 120mm stem is the length you need

also (since you're getting a custom bike) make sure you design it with a setback post in mind

personally I think your best bet is to find a stock geometry that works. even if you get a bike from seven, serotta, if, etc. geometry isn't just about being comfortable on the bike--it's also about handling and proper balance/weight distribution over the wheels. manufacturers put a LOT of thought into their stock geos. think of it this way, their (any manufacturer/builder) stock geo is their best version--try not to deviate to far from it. and custom isn't about mucking with geometry (except when absolutely necessary), it's about defining the ride based on your input re: things like stiffness, comfort, etc, what kind of braze-ons you want on the frame, how you want to paint, etc. too many people seem to think custom is about doing some diy geometry because your arms are 1cm longer than most people your size, or some other sillyness. stock geometry, even for custom builders and manufacturers, is their best version of their product.

good luck
Interesting ideas and I agree about the stem. I'll probably go with 12cm. I'm not so sure about the seatpost though. I ride a zero-setback at the moment and am comfortable on it. I like the look of zero setback as well. Why would I go with a setback post - comfort?
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Old 12-21-06, 08:58 PM
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You shouldn't get too caught up whether the bike has a setback or standard seatpost. You might have short femurs for you height or the saddle you like has rails more rearward than some or place you on a different part of the saddle than others. I wouldn't change the STA from 73 to 75 just to use a setback seatpost.
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Old 12-22-06, 12:40 PM
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I have come to beleive that the most important measurment is reach. Personally I like the steering feel I get with a 12cm or even a 13cm stem (nothing shorter). I think this is true for a lot of riders. Thus when sizing for my last bike I was looking for a combination of seat tube able, head tube angle and top tube length that when combined with a 12 cm stem gave me ideal overall reach. I really like this calculator:http://www.competitivecyclist.com/za...LCULATOR_INTRO. When I first used it I was like WTF! the top tube length it generated was soooo short. But I've been riding my new ride that gave me those numbers (Colnago C50)for 3 months now and my overall reach is now pretty close to perfect. How the bike looks matters to me. I like the look of having the saddle in a rearward position. So instead of going with a 73 degree seat tube and having the seat shoved all the way forward I went with the 74 which lets me push it back and get the look I like. For me I am most comfortable way rear of the spindles. Where are you most comfortable? I think the other poster who talked about the downsides of going custom sizing has some interesting and probably valid points. Don't forget about avoiding excessive handlebar drop. For me I hate the look of super riser stems.

I think to properly size yourself you really need to give proper consideration to a whole lot of different factors, top tube length, seat tube angle, whether you like to be centered on or rear of the spindles, the amount of handle bar drop you are comfortable with, etc., etc. I think its a big mistake to not give consideration to these things, buy a frame that isn't quite right for you body and then do stuff like pushing the seat way forward, going with really short stems, etc.
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