New location

Come on over to my new site:

Going to be posting regularly there.

Saturday, April 18, 2009

Guru Sidero - steel road bike *Now on Sale*

So this is another Studio demo/floor bike. I decided to try out the new steel offering from Guru, and I must say, it turned out great.

I pieced the build kit together to match (as you can see) the bike's paint, and the result is striking, I think.

I order the demo bikes with my own Studio signature geometry -- basically I tweak the stock geometry provided by Guru so that it fits the cyclist(s) I think would be interested in such a bike.

Head tube = 14 cm
Effective Top Tube = 50 cm
Standover = ~73 cm

The bike is built with SRAM Force throughout, Ritchey Pro Alloy kit, and Fulcrum Racing 7 wheels.

The Fulcrum wheels were a nice addition. This year they changed the wheel from having red accents on the decals to the hubs, rims, and nipples all being fully anodized red. They really make the look of the whole bike.

I have again used the SRAM SuperLight bar tape -- this time in red -- it just has a great feel to it and it wears extremely well. I have two clients that I built bikes for a year ago. Just did a check-up on their rides and the tape still looks brand new; that is considering a lot of miles and a couple of trips overseas with the bikes.

This complete bike, for full custom geometry, is $3950 with a Force group and about $3300 with a SRAM Rival set up.

I think this is a really great pricepoint for a non-pricepoint bike.

Monday, April 13, 2009

What are our muscles really doing when we pedal?

So my fit Studio is in a  Physical Therapy clinic, which makes sense, because I am a practicing PT.  My co-worker, and owner of the PT clinic, Rik is trained in a new biofeedback system.  Biofeedback uses electrode patches placed over the muscles to determine how much these muscles are working -- how much, how soon they kick in, how long they stay "on", how they "turn off", etc.  As you can imagine, this is highly useful with our clients.

So we decided to test a few cyclists and see what we came up with.  We could simultaneously use the Retul, to pick up movement imbalances and then cross reference with the biofeedback to try and figure out what the muscles on each side of the body were and were not doing.  We can even then use the biofeedback while the person pedals to "train" them what activating certain muscles at specific times "feels" like to help correct the underlying muscular problem.

First we have to test as many people as we can, to start to figure out common muscular patterns.  Hopefully we can figure out what is "normal" but if my line of work has taught me anything, it's that there aren't many "normals" out there.  That's why I think it's more likely we'll find common motor patterns that may not be symmetric, amongst many athletes.

Subject #1 : Me, 33 y/o, male, 5'10", 175#

I have a fairly symmetrical pedal stroke.  If I had to guess I would think that I am a bit right side dominant, and probably scoot off the right side of my saddle because of it.  But we don't have to guess, because here is a right and left Retul file from a recent test on myself:

Not bad.

Next was to hook up the biofeedback.  This involves placing small sticker-like electrodes strategically over the muscles you want to test.  Wires snap to the electrodes and run to a little processing unit that reminds me of a car radar detector.

The "radar detector" talks to the laptop via a BlueTooth connection -- the setup is pretty slick.

The software that Rik uses seems to have endless choices on how to set up the display screens so that you can simultaneously see what the
 different muscle groups are doing.

  When I was hooked up to the biofeedback unit we decided to test vastus lateralis (VL) (the quadricep or thigh muscle on the outside of the
 leg -- this tends to be very pronounced in cyclists), vastus medialis (VM) (quad to the inside just above the knee, and the hamstring.  We tested these muscles on both legs, so we could compare how much more the right or the left lateral quad was working, but we could also compare how much and when the medial vs. the lateral quad did work on the same side.  We could also compare this to how the hamstrings worked.

We tested all three muscle group -- VL, VM, hamstring -- on both legs, of course at 150 watts and at 215 watts.

The printout from the biofeedback looks like this:

The lines and squiggles at the top half of the page are usually in color, but they are a bit above what we want to get into here. 

Below are the printouts bottom half of the page.  The colum to focus on is the one that says "Mean" -- they are basically the normalized mA that the electrodes pick up from each of the

There are four sets of data:  comparing VMO/VL at 150 Watts, VMO/VL at 215 watts, VMO/hamstring at 150 watts, and VMO/hamstring at 215 watts.

VM/VL @ 150 watts

VM/VL @ 215 watts

VM/hamstring @150 watts

VM/hamstring @ 215 watts

As you can see from the sheets, my right quads (medial and lateral) both work more than the left at all wattages.  But when I increased from 150 watts to 215 watts my left quads increased their activity 18% while the right increased 23% (VL) and 29% (VM).

The next round of tests, comparing the VM to the hamstrings on both sides confirmed an 18% and 29% increase respectively for left and right for the VM when going from 150 watts to 215 watts.  The hamstrings, which overall, were not very active increased 31% on the right and 38% on the left; this increase on the left might make one think that the left "evens out" at higher wattage, but I think it is still a bigger issue: the right hamstring was more active at 150 than the left was at 215.  The fact that the starting point for the left hamstring was so bad made it's improvement seem more drastic.

What did we learn?
I think this first round of tests is encouraging and shows that we can, with good effect correlate what our mechanics are like (from the Retul data) and what the muscles themselves are doing.  We should be able to explain why a cyclist may pedal with an asymmetry and whether it is due to a poor motor plan or if it has more structural origins.

I think we can safely say that one of the main reason that I sit a bit skewed on the saddle is because my pedal stroke's motor plan has a significant emphasis on my dominant right leg.  I think with more data we will see that my current pedal stroke is poor in the efficiency category because I have not been riding as much  lately and I am getting a very small contribution from the hamstring muscles.  I am not "pedaling ellipses" but rather more up and down (and definitely more down than up).


I have a theory as well about the activation of our quadriceps when we pedal that has to do with left and right efficiency.  I believe I am more coordinated (because pedaling is a coordinated task) on my right leg -- it's clear my hamstring are more active on the right and help to smooth out my pedal stroke.  I am also more skilled at one leg pedaling drills on my right leg -- less "clunking" through the stroke and better cadence.  

I think, based on some of the muscle activation graphs that I saw for me (and they would have been difficult to post here -- sorry), that our more efficient leg will see the quads activate later and relax earlier than the non-dominant side.  So the non-dominant side will have a more consistent or longer activation patter than the dominant side.  

This to me seemed counter-intuitive at first, but after some thought I realized that because my dominant side hamstring were activating better, they would inhibit the quads sooner since the load was now taken up by this new group of muscles -- the more "normal" or efficient pedal stroke.  The dominant side could more accurately and quickly kick itself on and off in time with my cadence and when it kicked on it could fire more motor units more quickly.  I think this would have implications, of course, on negative torque values (when your quads are still pushing down on the pedal after it has passed the dead bottom center position and therefore exerting negative torque or power) but also in terms of fatigue.  The non-dominant quad is staying "on" longer, even when it shouldn't and wastes unnecessary effort -- it fatigues quicker even though it is adding less to the overall workload.

Anyway, I should have more data coming this weekend and next week with a  few more guinea pigs so stay tuned.

Thursday, April 9, 2009


I had to post these pictures.  I don't haul this much normally, of course, but today I had to bring a number of things in to work.  This is why I love the Surly Big Dummy.

I had to get all of this onto my bike (well I could have driven, but that would be cheating):

And here is how I did it:

I love this bike

Wednesday, April 8, 2009

Talkin' bike seats

I mentioned in my last post that, for the average woman, and ideal seat design would be wide in the back to support the wider ischial tuberosities, but then needs to quickly narrow to avoid compressing the tissues distal and lateral to the sit bones. 

This narrower space between the femur and sit bones that we tend to rest (which ends up being the proximal hamstring -- medially the semi-membranosus and laterally the biceps femoris) is not the only reason for this saddle shape.  The woman's sit bones are oriented more in the frontal plane (more side to side) than a man's.  The male sit bones are set more in the sagittal plane (front to back).

When you factor in the natural translation of the hips and pelvis downward at the bottom of the pedal stroke, you can visualize that the male sit bones can more readily follow this path of movement -- sort of like a knife blade slicing through the dirt.  The female sit bones can't move as easily in this path -- imagine running the same knife through the dirt now turned to it's side a few degrees, like a plow.  The amount of shear force (or at least the potential for shearing) is much greater.

Essentially, all the angles of the pubic and ischial rami (the structures that form the "loops" on the bottom of the pelvis, and that we sit on) are steeper and sharper and because of this, less contact with saddles is probable.  I think this is the reason women often struggle with saddles -- more contact and shear forces -- and not just the fact that they have wider sit bones.

Saddle position

Of course, the right saddle is nothing without it being fit in the right position.  Many cyclists are on saddles they are unhappy with, but the reason is that they are not sitting on the part of the saddle that is meant to be sat on.  Most are scooted too far forward, even to the point where the sit bones don't rest on the saddle, but rather the saddle is squeezed in between them and the rider is resting more on their soft tissue -- this is a problem, obviously.  A huge mistake I see all too often is having the saddle tilted down --- yes, even a little is generally not a good thing.  

A bike seat needs to be in the right place fore and aft so that the sit bones can contact the wider, more cushioned portion of the saddle, and then it needs to be level so that the sit bones can rest on it.  If you aren't perched on your bike seat, then you aren't effectively stabilized to make full use of your pedal stroke. 

Think about this: 
If you have a seat slid all the way back on the rails, so that the seatpost clamp is at the front of the seat, and it is level.  What happens when you sit on the saddle?  What if the rails are made of Steel?  Titanium?  What I'm getting at, is that a saddle has a static (or unweighted) position and a dynamic (weighted) position.  The dynamic position is the only one that really matters.  It has been my experience that especially with titanium railed seats if the seatpost clamp is to the back of the rails the seat will flex downward, if towards the front of the rails the seat will flex backward.  Therefore I have allowed some seats to leave my Studio tilted up or down at times to accommodate.

This leveling of the seat brings me to my last point about a good seat -- for a man or a woman.  The seat should have at least some portion of it's surface should be flat and not fully sloping. 

This FSA saddle is a good example of when some seat designs can cause trouble for people.

The centerline of the seat is the high point and the cover slopes downward to either side.  I am sure there are people who find this saddle comfortable, but I haven't met them yet.

I am intrigued by the new fizik Antares -- the entire saddle looks flat.  I will have to try it out and get back to you on that one.

Next up :  Some top secret stuff going on in the lab.  Well, not really secret, but it should be pretty cool.  We are combining the use of the Retul dynamic "mo-cap" with a very sensitive biofeedback system so we can see what exactly some muscles are doing when we pedal, and using all the information (and there is tons!) to try to determine what the leg muscles are doing when....say, a knee tracks laterally more then the other side. 

From the preliminary findings, I think I can say that many will be surprised at what we are finding.