Road Cycling - Measuring overall reach per Wrench Science

I ran through the Wrench Science bike fit process, but I am unclear on one measurement, overall reach. There is a picture that is supposed to show how overall reach is measured, but it doesn't have any markings to actually show the measurement points. The narrative description says effective top tube length plus stem length. For instance, the procedure comes up with a measurement of 72.75 cm. My traditional horizontal top tube on the bike I am riding today measures 57 cm from center of seat tube to center of head tube. So that plus my 130 mm stem equals 70 cm overall length, right?

I realize that this particular measurement may be just a starting point and that there may be more appropriate measurements such front of saddle, rear of saddle, center of seat clamp, whatever. Right now I am just trying to make sure I am understanding how Wrench Science is defining overall reach.

I am going to try a 140 mm stem to get 71 cm reach, but I can't imagine using anything longer! That should be close enough anyway. I have already warned Rainbabe that I may be FORCED to have a frame custom made to accomodate my shortish inseam and long arms. She mumbled something about simian something or other, whatever that means. I could sure go for a banana right now.

I have heard alot of gripes about the reach and stem recommendations by the wrenchscience site. Maybe others like you do not know exactly what they are considering.I'd ask them what they mean.Go with what feels right.If you don't feel the need for the 140,why do it. Even bars have different reach and the position of the levers and stem angle also affects reach as does bar height. I ride 120/130 on my 57cm bikes.

Originally posted by RainmanP
I ran through the Wrench Science bike fit process, but I am unclear on one measurement, overall reach. There is a picture that is supposed to show how overall reach is measured, but it doesn't have any markings to actually show the measurement points. The narrative description says effective top tube length plus stem length. For instance, the procedure comes up with a measurement of 72.75 cm. My traditional horizontal top tube on the bike I am riding today measures 57 cm from center of seat tube to center of head tube. So that plus my 130 mm stem equals 70 cm overall length, right?

I realize that this particular measurement may be just a starting point and that there may be more appropriate measurements such front of saddle, rear of saddle, center of seat clamp, whatever. Right now I am just trying to make sure I am understanding how Wrench Science is defining overall reach.

I am going to try a 140 mm stem to get 71 cm reach, but I can't imagine using anything longer! That should be close enough anyway. I have already warned Rainbabe that I may be FORCED to have a frame custom made to accomodate my shortish inseam and long arms. She mumbled something about simian something or other, whatever that means. I could sure go for a banana right now.

Rainman, I used WrenchScience's measurements also to start my build. I centered my saddle first and put an imaginary line from center seat post up through the saddle. I sat on it, then measured my top tube to center, determined the needed deda pro stem length to accomdate 66.23cm Overall Reach ctr to ctr.

I took all the measurements including overall reach (mine=66.23)and I told my LBS to applied these measurements to my bike build setup. It worked great for me. My shoulder width came in @20" so they suggested a 46cm bar. My LBS strongly suggested going with 44cm due to choices and thought it would be accepable... I stuck with 46cm and it was the right decision for me.

RainmanP

I guess I posted the earlier mention of the Wrench Science site and commented that we have a similiar build-short inseam and long arms. You are right with your assumption concerning the total reach measurement with Wrench Science. On the final page of the measuring part, they include small pictures on the left. IF you clicked on the picture, a line used to come up to show the way in which the measure was taken. I see that it no longer does this. Anyway top tube centre to centre of bar is the effective reach-ie. top tube + stem length. No reference to seat positioning though which is how I am cheating by putting it all the way back. I am going to go with either a 12 or 13 cm. stem to replace the 11. All the best at stretching out.

Thanks, Barnaby, that answers my question. The 140 mm stem came yesterday so I stuck it on and went out for 25 miles or so. Since I had a 130 already already so there wasn't a huge difference in feel. Seems fine. Seems like a long time (about a year) since I put on a 90 because I felt too stretched out. After a month or two I suddenly felt really cramped and started putting on longer and longer stems. This may be it!
Thanks for the help,
Raymond

I have always tried for a saddle nose - to - handlebar distance of a cubit or so: with my elbow against the nose of the saddle and my forearm parallel to the top tube, my fingertips fall just short of the handlebar. I am usually comfortable with a gap of less than 2cm.

Saddle height: I used two methods to determine saddle height:

1-Standing with feet 12 inches apart and wearing cycling shoes, with a hard cover book under the crotch immitating normal saddle pressure, and with the back of the book to the wall (the top of book would not dip)-the distance from the floor to top of book -times this by 1.09. From this you get the distance from the pedal axle at 6 o'clock to top of saddle.

2-The wrechscience approach with the same book against the wall with bare feet and feet together-distance from the floor to top of book. From this they determine top of saddle height from mid-bottom bracket.

For me the two results for the saddle height were within .7 of one cm.

The method #1 is from the book The Custom Bicycle by Kokin and de la Rosa, who also suggest the method of putting both heels on the supported bicycle and having a slight bend at the knee, and then pedaling backward while being checked so that you don't alternatively sway with each stroke. I found I could only do this at a the low saddle height arrived at above.

Fore/Aft

This same book says, "The height of the saddle corresponds to the overall length of the rider's leg-the horizontal saddle adjustment corresponds to the size of the rider's thigh. ...in other words, the horizontal saddle adjustment is used to insure the proper angle of thrust of the leg." A plumb from the centre of the knee should extend through the pedal axle at 3 o'clock.

The stem length

They mention the forearm method mentioned in an earlier post by discourage it as they say it does not take into consideration the length of the forearm relative to overall arm, or relative to the upper body length. For stem they recommend putting the seat one inch lower than the saddle and sitting on the seat in the drop position, a plumbline from the nose should be one inch behind the handlebar.

Leverage

This book goes into the topic of why the cycling positon is bent over. The author says that whenever he asks anyone they tell him that it is for "reduced wind resistance." He disagrees with this and says that the position is for leverage and paints and example of putting a bathroom scale next to a wall and then asks you to press down on it fully with one foot. The result would be that you could exert a pressue equal to 50 to 75% of body weight. If you were to attach a set of handlebars 3 feet off the ground and were to grab the bars and press down with your foot, "the increased leverage gained by using the combined strength of your hands, arms, back, and shoulder muscles will cause the scales to read in excess of your body weight. Since bulk power is not the sole factor governing cycling efficiency, the designs over the years modified the bicycle to best utilize the advantages of leverage while also considering the factors of fatigue, comfort, and wind resistance." I thought that was interesting.

Interesting post, Barnaby! A year or or so ago I posted a thread asking how to determine crank length. Another BF poster suggested the difference between the 1.09 (for pedal at 6:00)and .883 (center bb) calculations as a good place to start.

Its worth reading Peter White's article on fitting a bike.

How much of the total length is in-front of the bottom bracket, and how much is behind? When comparing or setting up 2 bikes, I mark the BB position on the top tube, and measure back to the saddle nose, and forward to the brake hoods.
Im dubious of any fitting guide which suggests a specific reach for a certain sized person. It is best to start with a conservative position, and experiment to see what you like.

MichealW

I think that what you say concerning setting up two bikes is correct: I am doing that right now with my touring bike and my racer, to the extent of using the same saddle. If I was to use a formula derived from body measurement and flexibility alone that would not account for the extra reach for the brake hood position on the tourer, and, what you are I think referring to: the seat tube angle. That is much steeper on the racer. So, I am going use your advise about measuring back and forward from a line from the bb to the top tube to account for this. Where do I look for that article you mentioned?

But, drawing the conclusion that bike set-up should not overly focus on body dimensions, but rather you should set-up for what a person prefers, is going too far the other way. To follow that logic, the Wal-Mart employee who knows nothing about biking is doing all that is required by getting you to straddle the top tube and then, if you can, advising that the bike is the right one for you. All the serious LBS' spend much more time sizing the individual with the prospective bike, and this usually dwells on the riding style and top tube length. If that is done properly, you would end up with a bike much closer to ideal that you could make small adjustmets to to accomodate personal style and preferences after the sale. If that is not done properly, you would have to make unfortunate adjustments to get closer to this ideal by getting longer or shorter stems, or moving the saddle too far back- which may be less than ideal for pedal relationship.

One piece of information in a book on racing technique by Bicycling Magazine said that the tendency is usually to put the saddle too high because this preference would use pedestrian muscles that we would normally use day to day. The point here is that many believe that there is an advantage to the lower set-up in cycling efficiency that seems strange at first, in the way that you seem to be loosing power and leverage by making the change. I used the higher set-up at 72 cm. for many years, including a return trip to Mexico from Canada, and now have the saddle set at 68 cm. I think there is immediate advantage, but it took some time to get used to, and is not something I would have done based simply on preference. I felt much more heat in the quads, and had to get used to using different muscle groups to various degrees in the crank rotation.

My bike store used the Fit Kit for sizing, but I did not see the results. They put on a 110 mm stem and moved the saddle back and that was about it. I think they threw out the results of the Fit Kit measurements in order to move a stale frame. It is 53 cm. both ways cc. The wheel base is therefore very short, and I have I think about 5 cm of overlap with the front wheel and foot at an exteme angle. I had nothing to compare it to, and it felt good to me. It was many years later, when riding with serious club riders, and watching the TDF that I started to question my set-up. I now believe that I should have at least a 56 cm. top tube, but am not in a position to buy something new. As a result, I am adjusting the bike to get the best fit possible given the fixed limitations.

I think the best approach to fit is to take whatever information there is out there and to go into a purchase with some understanding of what ideal fit should be. If you already have a bike, use the same information to set the thing up, even if it seems radical to you. After that, adjust for style and preference. Sorry for being so wordy, but the advice to: do what feels good -may result in somone buying the wrong bike or getting dropped in rides by those who simply have a better set up.

Barnaby,
The article MichaelW mentions is at peterwhitecycles.com.
http://www.peterwhitecycles.com/fitting.htm

The thing I like about the Wrench Science process and other fit systems for that matter is that it at least gives you an easily measured starting point. One can then decide from there what personal adjustments might be appropriate. I think this is more important for beginning riders. Some of the more subjective descriptions of bike fitting left me scratching my head, still unsure where to start.
FWIW,
Raymond

RainmanP-I agree that the systems provide a good starting point, but possibly not just for novices. I rode with the higher/forward seat since '79, and would not have changed if not for observing that others were riding with a radically different setup, backed up by the advice from various sources based on body dimensions.

The site is great, but it is interesting to note that he starts with crank lenth based on body meaurements, so he as well uses formulas to detemine setup.

Ideally he states that he would like to create an adjustable crank arm to go along with an adjustable stem and he stresses preference and the use that you intend. The trouble is that, at least in the choosing of a bicycle, even if you could find someone with the knowledge of the writer, it would still be impractical and usually not possible to work out all the variations possible prior to finalizing a sale. You have to ride for awhile over at least afew weeks before something starts making sense and overcomes the strangeness of the change.

All his points about balance, and efficiency and head positioning relative to top tube and stem (overall reach) are very interesting, and he makes the point that other factors need to be in play in setting this position, but bottom line is you will have to put your money down on something with fixed dimensions in the frame; you will have a choice of less extreme "fixes" if the top tube is ballpark to begin with.

I know that 10 years ago I was not able to hold the drop position for more that 3 minutes at the higher/forward seat position and the old saddle. I just assumed that it was not for me for whatever reason. Since the changes, I am able to hold the drop position for 50 minutes at a time without going upstairs to the brake hoods. Now I find it strange to go "to the hoods" and quickly switch to the drops. My time over a clocked event has improved by 30 minutes over a 64 km. distance, and I attribute this to better fit on the bicycle.

You know it may be that those who say that fit is simply a matter of preference are experienced cyclists who have over the years worked out all the variables, and have forgotten all the help they have had over the years from riding buddies and other influences to come to the final setup. The first thing a cycling coach would do is examine the setup based on prior understanding (biases) of what he thinks makes sense. In the absence of a coach, I am open to whatever sources are there to offer suggestions.

This is my best explanation for taking measurements. It is super simplified and assumes that we are starting from scratch. It does explain how Wrench Science and some others do it. Hope it helps.

Tools you might need for this job:

A measuring tape that uses centimeters
A wax pencil, crayon, something that will make a removable marking
Scotch tape
A level
A piece of string
A paper clip
A meter stick

Note: It is best to take take these measurements from the left (or non drive side) of the bicycle. You can stay clear of the greasy chain and be more accurate.

Frame Size center-to-center: Is from the center of the bottom bracket to the center of where the top tube meets the seat tube. The measurement should be made in centimeters, keeping the measuring tape parallel to the seat tube.

In cases of sloping frame, the same measurement will be taken in the same way.

Please reference the picture below

https://mail.google.com/a/wrenchscience.com/?ui=2&ik=12e1034361&view=att&th=12648239199f4590&attid=0.5&disp=attd&realattid=ii_12647fd726167cf6&zw
The dark circle at the bottom of this picture is used to represent the bottom bracket of a frame. You may have a crank installed in the bike. If you do simply create an imaginary line in your brain that runs through the center of the bottom bracket through the cranks. Visualize that point. Make a mark with a wax pencil or erasable marker if necessary. This will be point A.

The top tube and the seat tube are joined together under the saddle. Find the very center of the where the tubes connect. Make a mark at that joint and call it point B.

Begin your measurement from point A. Run the tape measure along the seat tube. End your measurement at point B. In the illustration above the reference line is LINE X.

You will also notice LINE X1. LINE X1 is the center to top measurement. It also beings at point A. It is taken in the same fashion, but ends at the top of the entire seat tube. The top of the entire seat tube is point B1.

Overall Reach: Is a completely horizontal measurement. You can use point B1 and your other tools for this one.

First cut a piece of string about 10 inches long. Second, tie the paperclip to one end of the string and a piece of tape on the other end of the string. Third, find point B1. Tape the top of the string to the saddle so that the length of the string will hang (being weighted by the paperclip) straight down (vertically) and intersect with point B1. You may use a second piece of tape to secure the vertical line to the bicycle frame. You have now created a vertical axis with which to begin the overall reach measurement.

Next, find the center of where the head tube meets the top tube. That will be point C. Point C1 will be a point you can find by extending point C directly up to the top of the top tube.These points are found in the same way that the B and B1 points were found.

Use the wax marker to draw a line on your stem that runs up vertically from point C1. Use the level to find a horizontal line that will start at the vertical string and end at the vertical line on your stem. Once you have determined that the line is horizontal you can measure it in centimeters. You can do this by holding a meter stick to the level.

https://mail.google.com/a/wrenchscience.com/?ui=2&ik=12e1034361&view=att&th=12648239199f4590&attid=0.7&disp=attd&realattid=ii_126481fc3335aef5&zw

These horizontal lines are how you find the correct top tube length with regard to how a human fits on a bike. It works when you are measuring classic geometry, slightly sloping top tubes, women's specific bikes, mountain bikes and compact frames. Sometimes you may have to use a longer piece of string.

Finally, find the stem you are currently using and measure it in centimeters from the center of where it clamps the fork to the center of where it clamps the handlebar. Add the length of the stem to the length of the top tube. This is Overall Reach.

https://mail.google.com/a/wrenchscience.com/?ui=2&ik=12e1034361&view=att&th=12648239199f4590&attid=0.6&disp=attd&realattid=ii_126481f740fe2401&zw

Sometimes shops are good for interpreting and applying these numbers to their frames. We know things like unit of measurement, point of measurement, and labeling of points can differ between manufacturers. :)

-Mary

This is my best explanation for taking measurements. It is super simplified and assumes that we are starting from scratch. It does explain how Wrench Science and some others do it. Hope it helps.

Tools you might need for this job:

A measuring tape that uses centimeters
A wax pencil, crayon, something that will make a removable marking
Scotch tape
A level
A piece of string
A paper clip
A meter stick

Note: It is best to take take these measurements from the left (or non drive side) of the bicycle. You can stay clear of the greasy chain and be more accurate.

Frame Size center-to-center: Is from the center of the bottom bracket to the center of where the top tube meets the seat tube. The measurement should be made in centimeters, keeping the measuring tape parallel to the seat tube.

In cases of sloping frame, the same measurement will be taken in the same way.

Please reference the picture below

https://mail.google.com/a/wrenchscience.com/?ui=2&ik=12e1034361&view=att&th=12648239199f4590&attid=0.5&disp=attd&realattid=ii_12647fd726167cf6&zw
The dark circle at the bottom of this picture is used to represent the bottom bracket of a frame. You may have a crank installed in the bike. If you do simply create an imaginary line in your brain that runs through the center of the bottom bracket through the cranks. Visualize that point. Make a mark with a wax pencil or erasable marker if necessary. This will be point A.

The top tube and the seat tube are joined together under the saddle. Find the very center of the where the tubes connect. Make a mark at that joint and call it point B.

Begin your measurement from point A. Run the tape measure along the seat tube. End your measurement at point B. In the illustration above the reference line is LINE X.

You will also notice LINE X1. LINE X1 is the center to top measurement. It also beings at point A. It is taken in the same fashion, but ends at the top of the entire seat tube. The top of the entire seat tube is point B1.

Overall Reach: Is a completely horizontal measurement. You can use point B1 and your other tools for this one.

First cut a piece of string about 10 inches long. Second, tie the paperclip to one end of the string and a piece of tape on the other end of the string. Third, find point B1. Tape the top of the string to the saddle so that the length of the string will hang (being weighted by the paperclip) straight down (vertically) and intersect with point B1. You may use a second piece of tape to secure the vertical line to the bicycle frame. You have now created a vertical axis with which to begin the overall reach measurement.

Next, find the center of where the head tube meets the top tube. That will be point C. Point C1 will be a point you can find by extending point C directly up to the top of the top tube.These points are found in the same way that the B and B1 points were found.

Use the wax marker to draw a line on your stem that runs up vertically from point C1. Use the level to find a horizontal line that will start at the vertical string and end at the vertical line on your stem. Once you have determined that the line is horizontal you can measure it in centimeters. You can do this by holding a meter stick to the level.

https://mail.google.com/a/wrenchscience.com/?ui=2&ik=12e1034361&view=att&th=12648239199f4590&attid=0.7&disp=attd&realattid=ii_126481fc3335aef5&zw

These horizontal lines are how you find the correct top tube length with regard to how a human fits on a bike. It works when you are measuring classic geometry, slightly sloping top tubes, women's specific bikes, mountain bikes and compact frames. Sometimes you may have to use a longer piece of string.

Finally, find the stem you are currently using and measure it in centimeters from the center of where it clamps the fork to the center of where it clamps the handlebar. Add the length of the stem to the length of the top tube. This is Overall Reach.

https://mail.google.com/a/wrenchscience.com/?ui=2&ik=12e1034361&view=att&th=12648239199f4590&attid=0.6&disp=attd&realattid=ii_126481f740fe2401&zw

Sometimes shops are good for interpreting and applying these numbers to their frames. We know things like unit of measurement, point of measurement, and labeling of points can differ between manufacturers. :)

-Mary



Last edited by velogy (http://www.bikeforums.net/posthistory.php?p=10291016); 01-19-10 at 02:12 PM. Reason: want to make sure i don't sound like i'm talking down to anyone

Just over 7 years - impressive!

I had the same issue with the Wrench Science fit calculator. I prefer the Competitive Cyclist calculator.

http://www.competitivecyclist.com/za/CCY?PAGE=FIT_CALCULATOR_INTRO

Well, it may be a 7 year resurrection but a very good post by Mary - and a nice thread to read as well.

Personally, I have found the WS fit calculator completely nailed the fit for the MTB I got from them. The CC fit calculator was not too accurate for me, but this was for a road bike.