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Wednesday, January 25, 2012

Retul FIT - In depth review


So you have been serious about cycling for many years. You own many high end bikes. Perhaps you are even part of the "My pedal bike is worth more than my car club" and you are looking for maximum performance. Or you are suffering from ergononmic fatigue on your bike... RETUL is your answer. This is where the pros go. So why not experience the "pro" level goodies?

For me it was a combination of all the above mentioned. What I really wanted to do was figure out exactly why my lower back screams in pain on a tough ride or a hard race. It hurts quite a bit once the kilometres pile up on the road bike. I would say around 65 to 75 kms it starts to nag with pain. Once 90 rolls around it hurts bad, enough that you make a couple of pedal strokes, coast for a bit while trying to stretch out your back. It also kills me on the 3rd lap of the Ontario cup races. It basically cries mercy.

In the very early beginning of biking I remember people telling me all sorts of various ways of setting up a bike. "if you have a high seat post you pedal more efficiently," "You should tilt the nose of the saddle forward for clearance." "You need a big saddle to bar drop to maximize aerodynamics." I think from these comments is what made me try to keep on increasing the height when I didn't need to.

So I decided to seek professional help to improve my performance. I felt that this single sore back problem was holding me back in terms of performance and results.

I researched the internet trying to figure out who were the good fitters in the Greater Toronto Area. A friend suggested a guy based out of Guelph university who specializes in the Serrota fit system. I contacted him, but he was only doing fits for people wanting to buy a serotta bike.

So then with more searching I found Ian MacLean who runs http://www.imfit.ca/ and is certified on the RETUL system.

The RETUL system measures your body movements under load to determine you fit. It doesn't use static position or employ the KOP system (Knee over pedal).

 
It is the truest form of measurement on how your body interacts with your machinery. This is the 21st century now. We have technology and a lot of it.

Here is a youtube video on how RETUL works:




For the technical geeks out there. The Retul system uses IR LEDs that are placed on the pivot locations of your body. The locations are:

  • Widest spot on your shoe just outside of your little toe
  • One spot near your heal just aft of the buckle for shoe
  • The bump on your ankle
  • The bump on the outside of your knee to the side
  • Your hip right at the pivot spot is for your leg
  • Shoulder
  • Elbow
  • Wrist
I didn't have the luxury of an assistant with my camera and I was paying money for Ian's time so there were no photos of me during the fit session. So I'm going to steal photos from around the internet.



The IR LEDs are all in a chain on a USB cable that plugs into a laptop running Retul Software (back in 2008). The new RETUL fit systems have moved onto the IR LEDs plugged into a wireless transmitter you clip to your back pocket. The actual little IR LEDs are secured inside a little 25 cent sized plastic housing that has a velco backing. The opposite velco is what gets placed on your body with a sticky backing. Then there is a camera head mounted on a tri pod about 7 to 8 feet away. This camera head is similar to the 3D scene cameras used for many robotic vision systems. This one is about 30 to 35 inches long and I believe it has 4 or 5 IR sensors in it. I forget.



The camera/tripod is placed so that it views you from the side. From what I can gather, the 4 or 5 IR sensors are able to triangulate the IR LEDs in 3D space to map out the motions of your body as you pedal your bike. (Basically how XBOX 360 kinetic works) Your bike is placed on a trainer and you are instructed to pedal as you would trying to follow a fast group ride on the flats. So about 250 to 300 watts at 100 rpms average.

So before all this, an assessment is made on your flexibility after you have warmed up on the bike. Apparently I have very good hamstring flexibility as Ian was able push my leg beyond 90 degrees with the table I was lying on with the other leg flat on the table. However my hip flexibility was below average. Imagine using both your hands to hug your knee into your chest. I was not able to bring my knee close to my chest. This raised some concern for him for fitting the road bike as hip flexibility is quite important. He taught me some after ride stretches to help increase my mobility/flexibility. Over time he said it should improve a little. Since doing this RETUL fit session back in 2008, I did 1 full year of yoga 2 times a week. Out of all the stretching and other exercise. I can honestly say YOGA is the way to go for flexibility improvement. More on that another day.

Ian looks over your bikes to see the general setup. He remarked at my slightly tilted back saddle (nose pointing up slightly). He said that was very very good. Any saddle that needs to be tilted nose down to be comfortable is the wrong saddle for the rider and he/she needs to find a different model or make. I asked him to go in more detail. He said the saddle serves to support your weight just like the pedals, and the handle bars. If you nose down the saddle you are constantly fighting your body not to slide off your saddle. You fatigue your body by using more of your legs to hold you up (pressure on pedal) and your hands/arms to hold you up. It is wasted energy. To all the male riders out there, a saddle pointed up at the nose will not cause you to go numb or make you sterile. That is a bunch of BS!

So back to the bike. Once you get to quick pace (100 rpm, 250 watts), the program records the IR LED movements. Real time it displaces a stick figure on the computer screen animated your body with the pivot locations. Then once the recording stops (about 20 to 30 seconds), a table is presented with the various metrics. Metrics such as knee angles at X degree of crank, knee angle flexion, ankle angle range, etc... Ian looks at these and starts assessing what should be adjusted on the bike to correct these values. I believe he works from both experience, and what Retul recommends.

Not so good Knee trace, notice the doughnuts
 
1st adjustment - saddle. My saddle is too high on the road bike. So high that I was adjusting saddle forward to try to reduce the strain on my hamstrings. Ian lowered the saddle, and took another data run. He still was not happy. Too high. We must have lowered it 1 to 1.5 inches. He studied the knee tracing which is similar to a hysteresis plot of how your knee is moving  through 3D space. My 1st run showed a big doughnut as my saddle was too high. It made my knee move in and out of the frame to try to compensate at the top and bottom end of the stroke. My knee also traced out at an angle. Very bad according to Ian. He believes this is a major contributing factor to my lower back pain as I was over stretching my hamstring. This then causes the hamstring to pull down on the hip flexor muscles which tie into your lower back.

2nd adjustment - saddle fore and aft. Looking at the knee plots, knee angle, hip angle, he said my saddle was now way too far forward at the new saddle height. He moved it back roughly 1.5 cm.

3rd adjustment - Cleat position. He moved my cleats slightly closer to the ankle to help the foot angle with respect to the ground. When my seat was too high my toes were always pointed to the ground. He said I had adjusted my cleat based on this incorrect pedal motion and changed it to what it should be

Much better knee trace - notice not much "doughnut"

Couple of more tweaks and we played with raising the handle bar to the max my steerer tube had to offer (which was a lot) to slamming it down. He studied something like 8 runs of data and said my inital position of just the conical spacer was perfect. Moving the handlebar up the max didn't change my hip angle. But slamming it down to the bottom closed my hips even more, and I was suffering from poor hip flexibility. So he put it back to the original as it was more aerodynamic.

Then we turned the whole setup around 180 degree to work out if I had an inconsistency between my left and right side. The only thing needed was a slightly different cleat position as my left side of my hip was even worse than my right side.

So with the adjustments made today and what I've been doing since the beginning of the season, I figure I've dropped the seatpost about 3" in total prior to the fit session..

Then measurements of my bike was recorded down. But not by a ruler. By a handheld IR remote. It is the size of a TV remote. Has 4 IR LED on the corners of the device with a cable for USB power and menu control of software. The device then has a stylus / pointer with a ball tip. This ball tip is used to locate features on the bike, with the bike placed 45 degrees to the camera about 12 feet away this time. The IR
LEDs emit to the camera which then triangulate the 4 LEDs. It is like measuring your bicycle with a Coordinate-measuring machine (CMM).


  • Point for axial line going through head set is determined by placing pointer into the stem cap bolt
  • Highest point on saddle is then taken to determine the plane in which the frame exists in 3d space
  • Then rear wheel rim is traced out with the stylus while the camera records to determine the rear axle location 
  • A chain ring bolt is used to follow the rotation of the cranks through 360 degrees, this determines Bottom bracket location of bike 
  • stylus is placed near centerline of pedal axle to determine pedal spindle location and crank length
  • the circumference of the handle bar is traced out at the stem connection to determine the length of stem (with respect to the stem cap datum).
  • stylus is ran along the brake/shift lever to determine their mounting locations and contour
  • saddle contour is also traced out along full length to determine installed aft/fore location and saddle angle
  • high points on hoods is taken to determine mounting width 
  • the upper edge of the frame's headtube is traced out so that the total stem stack height can be calculated
  • front wheel circumference is traced out to determine front axle location, rake of fork, trail of fork.
Pretty cool to have your bike CMM'd within +/- 1mm accuracy.




Most of the session was spent on my road bike. I good 2 hours worth, and about 20 or so data runs.

Then mountain bikes... (you will need slick mountain bike tire for your rear wheel)

The same thing happened, except I did not need to put down 300 watts I only did around 150 watts. My Kona I had to lower the seat. Fore/aft was perfect. Cleat placement was perfect. Bar to saddle drop was
perfect too, and I can go lower if I wish without impact based on the data runs.

For the Lynskey I had to raise the seatpost. Push the saddle back. a bit. It was noted that on the mountain bike my hip angle is perfect.

The mountain bikes took about 30 mins each to adjust as they were pretty bang on and the fit was very similar even though one is a hardtail and one is a full suspension. I would say the value in the mountain bike fitting is not as great as the road bike. Because you shift your weight and your body position a lot to compensate for the terrain anyways.

So what I learened. My seatposts were all too high except for the Lynskey. (I've dropped every single bikes seatposts over the months since january). My fore and aft generally was too far forward. Also to help the lower back out, Ian suggested trying to spin up a hill on the mountain bike rather than trying to hammer up it mashing on the pedals. This results in fatigue on the hip flexor muscles which are directly linked the lower back.

On the road fit. I managed to increase my pedal cadence 10 rpm, and add 60 watts of power on the particular cog I was using based on the new adjustments. I also feel better on the bike and I'm not rocking
side to side as much.

The mountain bikes... With the adjustments fore/aft and slight tweaking of the saddle angle I'm not actually sitting properly on the saddle.

Also my posture on my bikes are poor. As I need to rotate my hips in by sucking in my abs and pushing my butt out. Rather than just sitting down on the saddle and bending my torso to reach the handle bar.

Here are examples of what report comes with your session. Back in 2008 the report is not as detailed as they are now.




Money well spent? YES. It cost me $380 CDN to do 3 bikes. I occupied maybe 4.5 hours of Ian's time. As each bike had to be setup on the trainer and then flipped 180 degrees to view both left and right.

I did the Retul Fit analysis back in 2008. 2 years later I can honestly say my performance is better. My lower back is not as sore. I feel more comfortable on the bike and my riding friends tell me that I can hold a straight line perfectly line on the road bike in a draft. No rocking side to side.

We spend a lot of time on our bikes. Especially if you are dedicated to racing and/or your passion. Would you drive your car barely able see over the dash board? Would you sit in front of your computer awkwardly? Some do. Those who do ruin their backs, wrists, necks... you name it.

$250 CDN for one session for 1 bike is worth it. Especially if you one of those who has a stem on their bike worth that.

1 comment:

  1. Wow! This bike is really cool and I want to have this. I think this is really good quality for a race. Hope someday I can ride on this kind of bike and experience a mountain bike trails. Road bike

    ReplyDelete

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