RoadBikeReview.com's Forum Archives - General


Archive Home >> General(1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 )


5'9" tall 56cm too big?(13 posts)

5'9" tall 56cm too big?Jefferson
Jun 30, 2001 9:24 PM
I am re-evaluating my frame sizing. I am wondering if I am on too big of a frame. I am 5'9" with a 32.5" inseam(measured in stocking feet from floor to crotch). Is my 56 cm C-T frame too big for me? Or should I be on a 55cm frame? I would appreciate any other riders that fit my profile to comment on what size they ride. Thanks.
re: 5'9" tall 56cm too big?LC
Jun 30, 2001 9:56 PM
I would not pay any attention to the seat tube at all. The big question is your top tube too long that you can't reach the handlebars?
Depends on how the frame is measuredAndy
Jun 30, 2001 11:23 PM
I am 5' 9" with a 32 inseam. I ride a 56cm OVLV frame and a 53cm LeMond frame.
re: 5'9" tall 56cm too big?JohnG
Jul 1, 2001 12:30 AM
What size stem are you using??? If you are on a 10cm or less then it is likely the frame is a bit big for you. I'd guess that a "normal" 56cm frame would be just about at the limit of sizing for you. I'm 5'8 with 31.75-32" inseam and use 54X54cm frames.

Don't sweat the standover issue.... not important at all. The important # is tt length and reach.
Good luck.
Magic Formula!!jpa
Jul 1, 2001 1:24 AM
Try this formula!

You'll need:
Assistant (prefferably someone you know or would like to get to know)
Metric Tape measure
Pencil
Calculator or an assistant thats good at math
book with a 1.5-2 inch binder

hold a pencil in your hand and extend your arm 45 degrees from your body and keep your arm straight. Now have your assistant measure from the pointy protusion behind your shoulder joint to the pencil in centimeters. Measure both arms at least twice and take the average.

Stand with your back against a wall with your feet (no shoes!) 6 inches apart. Take the book and place it between your legs with the vertical side of the book flat against the wall. Now raise the book till your voice changes or just before you start levitating off the ground. With the pencil make a mark on the wall using the top edge of the book. This is your inseam length.

Stand facing the wall with your feet 6 inches apart. Place the vertical edge of the book against the wall and raise it till the top horizontal edge of the book reachs the little notch between your collar bones. Mark the wall and take a measurement in centimeters. Take this measurement and subtract your inseam. This is your torso length.

Add your arm length and your torso length, divide by 2, add 4. This gives you your combined top tube and stem length. If you prefer a 120 mm stem, subtract 12 cm from your combined top tube and stem length. This number is your ideal top tube length.

Take your inseam in centimeters and multiply by .883 then subtract 18. This is your ideal seat tube length.

Keep in mind that this is not an exerpt from the bible and bike fitting is not rocket science and I am not the pope or a rocket scientist. Use it as reference, try before you buy and go with what feels best!
Holding pencilkenyee
Jul 1, 2001 7:25 PM
Do you hold the pencil in a closed fist or with the tips of your fingers? I can't picture this at all. Is there a web site with a picture? :-)
Here you go...PsyDoc
Jul 2, 2001 5:23 AM
This will give you an idea of what you need to do. To find the acromion process (the bone from which you want to measure)raise and lower the arm to determine its location, which is on top of the hinge point of the shoulder. The bone will feel about the size of an acorn or a peanut. Then, measure the distance from the acromion process to the object (pencil) held in the clenched hand. Repeat this process for both arms several times and take the average measurement. Good Luck!
Depends...(long reply)PsyDoc
Jul 1, 2001 12:05 PM
...partly on what type of riding you are doing. I disagree with JohnG. that seat tube length is not an issue; it is from a safety standpoint. If your standover height is non-existent, then I think that it could be possible for you to come to a stop in traffic, lose your balance and fall. Also, mounting and dismounting a frame that is too large for the rider is also dangerous. Personally, I have seen kids around here fall when they tried to put their foot down, because the bike they were riding was too big. Also, many of the kids that ride around here do not wear helmets...which boggles the mind. My wife rides a bike that gives her about 2-3cm of clearance and she has had some close calls when stopping in traffic that would be non-existent if she had more standover clearance. And, yes, I am getting her a new bike that provides more standover clearance. They say that 2-3cm of clearance is fine, but I think that can be a dangerous generalization. In fact, I think that people tend to buy bikes that are too big, because they "feel" safer riding them at first or they get talked into a bike that is too small, because the LBS only has that size frame in stock or any number of other reasons.

I still use the tried and true method of inseam x .65 for a center-to-center (c-c) frame measurement and then add 1.5cm to 1.8cm for a center-to-top (c-t) frame measurement. I spec out at 54.9cm. If you are in-between frame sizes that come in 1cm increments, then go with whichever bike feels more comfortable as you are unlikely to feel the difference of 1cm.

You have an an 82.55cm, assuming you measured correctly, in bare feet. When you took your inseam measurement, did you pull up on the book or whatever you used until you could pull up no farther? Basically, you want to "hit" the pubic bone. What is the standover height of your 56cm bike? I would guess somewhere around 80cm. Now, if you take your inseam measurement with your cycling shoes on, then you are likely to get a figure around 84cm. If so, then you are fine and you can turn your attention to the toptube measurement. Do you feel too stretched out? If so, then maybe you want to run a 1cm shorter stem until you become a bit more flexible. Personally, I would not want a stem that is less than 10cm or greater than 12cm.

Do the calculations that "jpa" offered in his "Magic Formula" post. But, as "jpa" stated at the end of the post, use this as a reference. If you can touch the tips of your fingers to the ground (i.e., you are pretty flexible), then you can add 1cm to this figure. If you can place your palms on the floor, then you could probably add 2cm to this figure. Also, do not forget that you can be making errors when you take these measurements and be off by 1cm or so. For example, using the magic formula (also the same one Excel Sports uses), I spec out right at 66.5cm and I am riding a 56cm bike that has a 56.1cm toptube. According to the formula, I should be on a 10cm stem and was for a few years, but a 10cm stem is much too short for me and I always felt "cramped" when I rode. I switched to a 11cm stem and it is better, but I could still go to a 120cm stem, but I can touch the floor with the palms of my hands. In fact, a Serotta fit put me with a reach of 68.5cm. That value gives me a range of bikes that I could ride...anywhere from a 55cm bike with a 13cm stem to a 59cm bike with a 10 or 11cm stem (depending on manufacturer of course).

I am in the process purchasing a 57cm bike c-t that has a 55cm c-c measurement. Recall that my c-c measurement is 54.9. The next frame size down has a c-c measurement of 54cm, so I could go up 1mm or down 9mm. I would rather go up 1mm than down 9mm and have less headtube spacers. But again, this is my personal preference; I am sure others have different views.
responseJohnG
Jul 1, 2001 1:35 PM
If you get the TT length correct the standover will ALWAYS be acceptable.
JohnG
Agreed...PsyDoc
Jul 2, 2001 5:12 AM
...unless of course the person has very odd proportions.
yes nmishmael
Jul 1, 2001 4:56 PM
mn
re: 5'9" tall 56cm too big?JimF
Jul 2, 2001 5:51 AM
I'm the same height and inseam. I ride a 54cm (c-c) frame with a 120mm stem. The standover clearance is minimal. I need a long seatpost for good leg extension and usually keep my stem at or near maximum height.
I don't race and don't have the needs of a racer but have had some quality race coaching where my riding position was scrutinized and approved.
Your optimimum setup likely will be significantly different, but this is what has worked for me.
Get measured from a professional shopMaillot Rouge
Jul 2, 2001 10:07 AM
that specializes in road bikes. I'm 5 ft 9.5 inches, 6'1" with the fro, and I ride a 56. I always agonize over size when I get a new bike because I think we're between a 54 and 56. I have longer legs, 32 in inseam and a shorter torso. I almost went with a 54 but after being measured my LBS confirmed that 56 is the size for me.

MR