Welcome to rewind (Late) Friday. Sorry about the late entry, folks.

Along the vein of bike fit, to go with our lecture on onlinece.com this week, here is gentleman with right sided low back pain ONLY when ascending hills on his mountain bike. Can you figure out why?

*Stop, watch the video and think about it before we give you the answer… .

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This gentleman presented with low back pain, only on his mountain bike, only on long ascents.

He measures out with an 83 cm inseam which should put him on a 44 to 45.5 cm frame (measured via our method). His frame has a dropped top tube and measures 55 cm.

He has a knee bend angle of 20 degrees at bottom dead center. Knee is centered well over pedal axis.

His stem falls far in front of his line of sight with respect to his hub. Stem is a 100 mm stem with a 6 degree rise.

There is a 2" drop from the seat to the top of the handlebars.

He has an anatomically short Left leg (tibial)

Look at the tissue folds at the waist and amount of reach with each leg during the downstroke.

The frame, though he is a big dude (6’+), is too big and his stem is too long. He is stretched out too far over the top tube, causing him to have an even more rounded back (and less access to his glutes; glutes should rule the downstroke and abs the upstroke). This gets worse when he pushes back (on his seat) and settles in for a long uphill. Now throw in a leg length discrepancy and asymmetrical biomechanics.

Our recommendations: smaller frame (not going to happen) lower seat 5-7mm shorter stem (60-75mm) with greater than 15 degree rise lift in Left shoe

We ARE the Gait Guys, and we do bikes too!

What a difference a lift can make.

More from the pedal freaks….

Yes, we watch folks on bikes too. We look at foot and knee position, smoothness of strike, back position, as well as the spandex. Gait and biomechanics are everywhere and no one is safe from “the gait cam”.

Take a look at this gal and her pedal stroke. The first 9 second portion of the clip shows her pedal stroke with an increased medial migration of her L knee. Notice at about 4 seconds when she increases her cadence, it exaggerate the issue (see out post on that here). What sorts of things could cause that? A few causes are:

•  Leg length discrepancy
• Collapsed arch of L foot
• Poor foot intrinsic strength of L foot
• Poor eccentric contraction of L posterior gluteus medius complex
• Weak lower abdominals L > R
• Decreased ankle rocker of L foot
• Cleat positioning on L shoe
• Hip osteoarthritis
• And the list goes on…

In this particular case, she had an anatomically short leg on the LEFT and weak foot intrinsics. Yes, we know, folks tend to pronate heavier on the LONGER leg side, but this is usually with running, not cycling. It tends (but not always) to be opposite with cycling. We believe this is due to the more rigid lasted cycling shoe and more of a “reach” with the foot on the short leg side.

In the second part of the clip, from 10 seconds to end, we place a 3mm lift on the left. THAT’S IT. Wow! What a difference! Still some oscillation of the knee at the top of her stroke (present on both sides, but more pronounced on the left), but much less. Note also that her body oscillation lessens as well and her stroke is smoother.

The Gait Guys. Not only are we watching how you walk, but also how you ride