Friday, 12 February 2010

Specialized Body Geometry Footbeds and Shims

I have long been a fan of adding orthotics to my cycling shoes.

Our legs are 'designed' for walking, not for cycling. The natural canting of the foot (present in most people) helps to make walking very efficient, but while pedaling a bike, it can make the knee move from side to side (or rotate). This is inefficient and can sometimes cause repetition type injuries to ankles, knees and hips. Orthotics specifically designed for cycling, generally footbeds and shims, can be added to shoes to correct this problem.

I firmly believe that having a biomechanically efficient alignment between my pedals and shoes and my feet, knees and hips, improves my cycling and reduces my cycling related injuries.

Specialized BG Tahoe MTB Shoes, Footbeds and Shims

I've used Cyclefit in London a couple of times in the past for their racing shoe fitting service to achieve this. (I've also had an excellent bike fitting done there too).

Their shoe fitting service is quite involved and includes tests both off and on the bike. You are interviewed first about your cycling habits and then some biomechanical data and body measurements are taken. Footbeds and shims (if necessary) are added to each racing shoe based on the measurements and a static bike is used to assess the result. A laser sight line is pointed at each leg in turn to check the foot / knee / hip alignment and that the knee makes no side to side motion while pedaling. This is a great service and highly recommended, but it is expensive!

Since getting the Nomad, I've been using a pair of my 'tuned' racing shoes and a set of my normal road pedals, so that I could get used to the new bike position without disrupting my pedalling action. I also wasn't sure at the time, what I wanted to do about moving to a touring shoe setup and whether that would mean changing my pedal system as well. I'm pretty settled riding the Nomad now, so I decided to take a look at my shoe and pedal options...

Some more pictures (for shoe fetishists only...)

Of course, I was keen to set up any touring shoe I bought 'properly'. Riding across Canada would probably expose any biomechanical pedaling inefficiencies pretty quickly, especially as I'm used to pedaling 'properly'!

After a useful bit of forum researching, the Specialized Body Geometry system of shoes and footbeds jumped out at me. I decide to purchase the BG Tahoe MTB Shoe, a cycle touring shoe with good walking potential and the matching footbed and shim system. (Note that the footbeds and shims could be added to any cycling shoe, you don't need Specialized branded shoes).

I visited a Specialized Concept Store in Ruislip, West London, to try on shoe sizes and sort out the footbeds and shims I required. I was asked to stand on the Specialized "Arch-O-Meter", a thermal pad that measured the profile of my feet arches. I already knew that I had 'flat feet' and the "Arch-O-Meter" showed that impressively! That information enabled me to choose the most appropriate footbed profile (red or blue for me) and a selection of shims. While I was in the shop, I also picked up a pair of Mr. Shimano's (2nd) finest SPD pedals, the PD-M770 XT.

Shimano XT (PD-M770) SPD Pedal

Once home, I had more shoe setup data to gather! I needed to measure whether my forefeet were varus or valgus (or neutral). I already had a good idea that my feet were varus (as are about 85% of the population) from my Cyclefit shoe fittings. My right foot is also slightly more varus than my left foot!

The Specialized test involved performing 1/3 leg squats in front of a low mirror to simulate a pedalling action. You drop a plumb-line from the mirror and also mark a dot on your knee-cap. Then you line up your second toe, the dot on your knee and your hip with the plumb-line, perform the leg squat and observe the movement of the knee. For most people, this will result in the knee moving towards the centreline of the body. This indicates a varus forefoot. You perform the test separately for each leg.

You then repeat the test with the cycling shoes on. This time you're aiming to keep the knee in line with the plumb-line (and thus in line with your foot and hip). You achieve this by adding an appropriate shim (orange = varus = +1.5º, yellow = valgus = -1.5º), if required, to the inside of the each shoe, underneath the footbed. Zero, one or two shims may be needed. I ended up with one orange shim in each shoe!

So I'm now set up and ready to swap over my pedals and shoes. This should be interesting...


Stuart said...

I've used Tahoe MTB Shoes for at least 3 years and they've been fantastic.

My first pair had the sole start to come away at the front, I think this was probably due to me drying them out on a hot radiator to many times!

I contacted Specialized, they swapped them out, no questions asked and the new pair have been perfect ever since.

Considering I wear them most days and in all sorts of weather I'm amazed how good they still look.

Great choice and with the special insoles as well I think your tootsies are going to be rather snug on their trans Canada expedition.


Shaun said...

Thanks Stu
Glad to know these shoes should be up to the task! I'm finding them a little softer soled than I'm used to, but OK so far.

Regarding the footbeds and shims. These are retro-fittable as I mention. I know you're probably very comfortable already, having owned the shoes for so long, but it still might be worth you trying a set, if you haven't already. (You could stand on a piece of glass to simulate the Arch-O-Meter reading).

The shim correction for a varus foot is noticeable and could improve your pedalling action.

Might help on the long road to China...