New version V8. Biomechanical & sizing & fitting spreadsheet

A light bike doesn't replace good fitness.

Moderator: Moderator Team

Post Reply
User avatar
beatnik
Posts: 1237
Joined: Thu Aug 03, 2006 6:38 pm

by beatnik

Super_fast wrote:Some pictures, so everyone can judge me :wink:

Image

On a steep (10% avarage, but it's Holland so after 1k you're on the top):
Image

Image

And the last corner in the same race (the only one I won this season)
Image

The bikes are Ridley Excalibur in size M (toptube 565 mm, headtube 175), no spacers, 130 mm stem, oval seatpost (28 mm set-back). When I look at the pictures my postion doesn't seem to be so strange. I like to sit a bit stretched on my roadbike.


Your size is 58, that´s all, but even in your 56.5 your horizontal position is not the best, it must be at least 2 cm shorter, and your handlebar drop is huge. But spreadsheet considers 1.5 cm setback seatpost as standard. If your seatpost is 2.8 cm seatback, you must add 1.3 cm to your "best stem length". That´s what i mean, everything is important, just be patient and consider everything. :lol: :shock:
Last edited by beatnik on Fri Dec 26, 2008 7:52 pm, edited 1 time in total.
Biomechanical spreadsheet. Sizing&Fitting.

http://weightweenies.starbike.com/forum ... 8e319d185b

by Weenie


Visit starbike.com Online Retailer for HighEnd cycling components
Great Prices ✓    Broad Selection ✓    Worldwide Delivery ✓

www.starbike.com



User avatar
beatnik
Posts: 1237
Joined: Thu Aug 03, 2006 6:38 pm

by beatnik

Rezne wrote:I find that the spreadsheet puts me in a shorter position, compared to my current position (about 4 cm).
I ride a CR1, size L (Toptube 56 cm, heatube 17 cm) with a 120 mm stem. The spreadsheet 'tells' me to get a 85 mm stem.

I'm 1m 85 with 94 cm inseam. Fairly long legs. Like Super Fast i have quite a big drop: 16 cm

My new bike will be a different brand. One sizer larger: with a 58 cm toptube and a 18 cm headtube. We'll see how that works out.

Next monday i'll be fitted on my bike by an expert. I'll let you know what the result is. I'm curious to know the difference between my current position, the spreadsheet position and the new position.


That drop means wrong size. But we must suffer this new "standard geometry" wave due to the higher cost of carbon frames production and just work with 4 sizes at most. It´s not easy to fit your bike ok. It takes time. Just be patient.
Biomechanical spreadsheet. Sizing&Fitting.

http://weightweenies.starbike.com/forum ... 8e319d185b

Super_fast
Posts: 337
Joined: Tue Nov 01, 2005 9:36 am

by Super_fast

Your idea of fitting someone on a bike is just different then ours. As long as your power output, bike handling and comfort don't suffer from it more drop is just better. Look at the pro's that are more than 1m85, they all have a huge drop, ride with 13-14 cm stems and have quite often as much set-back as is possible.

Most seatposts have 25-28 mm setback. There was an Oval on the bike which was 28 mm. Less set-back means (for me) to much pressure on the front wheel.

User avatar
Tapeworm
Posts: 2585
Joined: Thu May 03, 2007 10:39 am

by Tapeworm

I personally like the big drop (16cm from saddle to bars tops). Power is not greatly affected and the aerodynamics are better I have found.

No point punching out huge watts if you are a parachute. Low is pro, right? ;)

User avatar
Amadeus
Posts: 1461
Joined: Sun Jan 08, 2006 5:53 pm
Location: Leiden, NETHERLANDS

by Amadeus

Super_fast

To compare with pr’s is wrong.
Most pro’s are fitted in an old fashion way to much se-back and way too long stem.
In the pro scene it’s still the team mechanics that rule .. It’s crazy but it’s reality!

IMHO you can ride this bike like I said I like small frames and quite some drop myself. But you would probably ride as good or better in a size bigger. Anyway the bigger bike would give you more options to play around with your position.

Beatnik’s spreadsheet is a good guide-line ….. that’s all!
My bike is Italian so it is Nervosa and of course has Anorexia I like them thin!
GIOS "New" Carbon Ultra 2006 Campa Record+Special parts.
GIOS "New" A90 2008 Campa Record+Special parts. My winter and vacation bike.

User avatar
ave
Posts: 2136
Joined: Sun Dec 28, 2008 10:15 pm
Location: Hungary

by ave

Very useful looking spreadsheet, nice work!
However, either it's not perfect, or I have a very extreme build.

181cm tall, 84cm inseam, 45cm elbow-middle finger.
Horizontal tube suggestion is 51.5 which is XXS size in Ridley, XS in Wilier. (smallest available)

Inseam doesn't seem to affect the horizontal tube length, so that calculation is based only on my lower arm's length. I've never felt that I have too extra short arms, but it seems that way.

My current steel bike has a 56cm c-c old-style horizontal toptupe, i use a 12cm stem with that.

User avatar
beatnik
Posts: 1237
Joined: Thu Aug 03, 2006 6:38 pm

by beatnik

Your elbow to middle finger distance must be reviewed, just put your arm vertical with your elbow in the table and take the measure. Perhaps i must consider to publish another version considering your trunk flexibility. But i think this one is the best because is very easy. I don´t want to be the best expert in the world, just a little help to choose your best frame and position with few body measures, and this one is the best way i´ve found because as i told before your arm length includes your trunk length considering a "regular" human proportion. Few mm. more ore less in any measure are not important at all, if you feel better...

But as i told before you must decide if you want a well fitted bike or a pro-looking one. In some cases riders prefer to look "pro" and ride long stems, with a lot of problems, or others just have the bike to show and watch it, and they don´t ride it at all, or less than 1000 miles per year.

PD: Most setback seatpost have 1.5 cm setback, but you have to know how to measure it correctly :lol: . Between axis ;)
Biomechanical spreadsheet. Sizing&Fitting.

http://weightweenies.starbike.com/forum ... 8e319d185b

User avatar
ave
Posts: 2136
Joined: Sun Dec 28, 2008 10:15 pm
Location: Hungary

by ave

beatnik wrote:just put your arm vertical with your elbow in the table and take the measure.


Now that makes a big difference.
It now comes out 48.7, altough this way there's about 1cm air between the 'bones' and the table. Anyway, 47.7 is still more than 45. :)

The little pictogram in the Excel sheet misled me.
Probably most people know that how arm lenghts are to be measured, I didn't.

Thanks!

User avatar
beatnik
Posts: 1237
Joined: Thu Aug 03, 2006 6:38 pm

by beatnik

Yep picture is not good, i´ll try to make a better one :lol: . So your best horizontal frameset is around 56 ;) for a 10 cm stem with a non setback seatpost. You are riding a 12, buy a cheap one and try.

The most important thing is to keep your saddle-bb distance and your saddle nose- handlebar distance, perhaps you can play with your saddle setback in order to obtain your best fit. But 1 cm is not very important. ;)
Biomechanical spreadsheet. Sizing&Fitting.

http://weightweenies.starbike.com/forum ... 8e319d185b

Landim
Posts: 9
Joined: Sun Dec 14, 2008 4:57 am

by Landim

The spreadsheet is a great starting point and worked nice for me, and what I think is that bike fitting is dynamic, and not static, so as you improve your form and gain strength and flexibility the fitting also changes.

User avatar
Amadeus
Posts: 1461
Joined: Sun Jan 08, 2006 5:53 pm
Location: Leiden, NETHERLANDS

by Amadeus

Good point Landim.

In the old days we started lower and during the racing season april/may we did rise about 1cm.
My bike is Italian so it is Nervosa and of course has Anorexia I like them thin!
GIOS "New" Carbon Ultra 2006 Campa Record+Special parts.
GIOS "New" A90 2008 Campa Record+Special parts. My winter and vacation bike.

Super_fast
Posts: 337
Joined: Tue Nov 01, 2005 9:36 am

by Super_fast

beatnik wrote:But as i told before you must decide if you want a well fitted bike or a pro-looking one. In some cases riders prefer to look "pro" and ride long stems, with a lot of problems, or others just have the bike to show and watch it, and they don´t ride it at all, or less than 1000 miles per year.

PD: Most setback seatpost have 1.5 cm setback, but you have to know how to measure it correctly :lol: . Between axis ;)


FSA makes there seatposts in zero setback, 25 mm or 45 mm. Ritchey WCS is 25 mm, Oval is 28 mm. Or do you measure it differently?

For the record, I do not have any problems with the way I am fitted on the bike. I did multiple training rides of more then 7 hours and never had pain in my back or something. I don't think Ridley sponsored the team to only show the bike :wink:

User avatar
Sacke
Posts: 643
Joined: Fri Sep 26, 2008 2:33 pm
Location: South of France

by Sacke

I did the fitting guide and it will be interesting to try out some of the results, although according to the fit guide I should have a stem that is 3,5cm!!! shorter!!!

My measures:

Length: 178cm
Inseam: 83cm
elbow to middle finger tip: 46,5-47cm

Frame: '09 Pinarello Prince, 53cm: 54,5cm top tube
Saddle height: 74cm
Stem: Deda Zero 100, 120mm
Handlebars: Zipp SLC2

At the moment my stem is about 1cm above the top of the head tube. In it's current position the reach from front of saddle, to middle of handlebars is 55cm.

I noticed that when you lower the stem 2cm, the reach increases roughly 1cm. Any exact figures on this?

Yesterday I was out riding and felt some neck and shoulder pain afterwards. I think one of the main reasons could be the increased drop that I am not used to yet.

I am going to try with a 100mm stem and see how the fram feels.

Which is more important for comfort? Drop amount or reach? (given the other parameter remains unchanged)

User avatar
beatnik
Posts: 1237
Joined: Thu Aug 03, 2006 6:38 pm

by beatnik

Your frame size is the best for you, that's a good start. But your handlebar reach is about 3-4 cm longer than you need. And that causes the pain in your neck, just fit your bike according to the spreadsheet and feel the difference. That´s about horizontal fit

Your vertical fit is not bad but is not the best, your best frame is a 54, and yours is 53, this causes that your handlebar drop is lower than your best. If your fork is cutted perhaps you must buy a more positive angle stem.

Not bad fit at all but need some touches to be the best. Be patient, and make changes slowly, fitting a bike is a long process :lol:
Biomechanical spreadsheet. Sizing&Fitting.

http://weightweenies.starbike.com/forum ... 8e319d185b

foz
Posts: 151
Joined: Mon Sep 08, 2008 3:37 pm

by foz

beatnik, I just found this thread, and after putting in my measurements, the results are all within 0.5cm of my current setup, so following your chart, I guess I'm pretty well set up already.
One thing that isn't clear from your chart though, is that on the first picture (of the litesped MTB), the saddle set back from the BB is at 8.6cm, with a comment that it's a very important measurement (which is true).
Later on, the stem length calculation is given for different setback seatposts. This is where I have to disagree with your chart - the stem length should always be the same, because the saddle position is fixed for a particular rider.
It is wrong to say that if I change my seatpost to one with different offset, then I should change my stem length to compensate. If I change my seatpost, it will clamp the saddle rails in another position, but the saddle position relative to BB will not change, so stem length will be the same.

foz

by Weenie


Visit starbike.com Online Retailer for HighEnd cycling components
Great Prices ✓    Broad Selection ✓    Worldwide Delivery ✓

www.starbike.com



Post Reply