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pins and needles in thighs/loss of power
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Alright everyone, got a perplexing fit question. Have a customer riding a cervelo p3. Had his set up with his tibial plateau 2.5-3cm ahead of pedal spindle but still rearward of front toe. Hip angle looked great, saddle position was solid, reach looked solid. Customer rode position for 1/2 a season or so and continually spoke about a diminished feeling of power. He did not have a way to quantify his claims aside from his subjective feeling. He's an experienced triathlete so I am inclined to believe his claims. His biggest issue he faces is a pins and needles sensation under heavy effort in his quads and a general feeling of weakness in the legs after the ride, especially the day after. At one point he said he could barely stand up because his legs simply weren't working quite right. He does seem to have a pelvic rotation where his left hip appears to be rotated ahead of his right hip. We moved the saddle back to try and get him to use less quad and more ham/glute. We raised the aerobar height and reduced reach to account for the shallower effective seat tube angle. He has been seeing a PT, doing core strengthening exercises, etc... Can anyone think of what may be causing the pins and needles? I don't know if its as much to do with the bike fit, but perhaps something nerve related. He says it comes on suddenly, and I can't think of a reason from a bit fitting perspective (aside from a nerve impingement) which may be causing the problem... Thoughts?
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Re: pins and needles in thighs/loss of power [carrera111] [ In reply to ]
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Did he also have a cleat fit? If not, getting that handled will at least let you know if it is the foot-pedal connection.

What does the front view show? Do his knees come in near the top tube?
What pedals?
Any other symptoms of any sort?

I have a few more thoughts but would like to hear this first.



Swifty

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Re: pins and needles in thighs/loss of power [Swifty] [ In reply to ]
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His cleats are moved a bit rearward from his first met head. He pedals on a vertical plane without much patellar lateral motion. He is using Specialized Trivent shoes with Shimano SPD SL pedals. He has lower back tightness from time to time, but he is well within his range of motion from a flexibility standpoint.
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Re: pins and needles in thighs/loss of power [carrera111] [ In reply to ]
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how is his posture?
That would be the first thing I would look into.
Does he have saddle discomfort issues forcing a posterior pelvic tilt?

Jonathan Blyer,
ACME Bicycle Co., Brooklyn, NY
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Re: pins and needles in thighs/loss of power [carrera111] [ In reply to ]
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I would suggest:
"Upright" MRI
X-Ray, standing, knees bent, hips flexed.
His symptoms suggest nerve impingement -- lower lumbar.
Place your finger in his Anterior Inferior Iliac Spine, and see if his Femur/Anterior Superior Iliac Spine crush it at the top of the pedal stroke. If the Ilium hits femur nearing TDC, it will impact low back/pelvic stability.
Also check that his pelvis is neutral on the bike:
Mark the posterior processes along his spine and SI Joints with marker.
Have him mount the bike with saddle 3-5cm higher than "Correct"
Stand behind him, and watch the movement at BDC on either side.
You are looking for excessive reach, but also vertebrate to vertebrate rotation/translation.
ccb
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Re: pins and needles in thighs/loss of power [carrera111] [ In reply to ]
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I would be getting him to a physician and investigate his lumbar spine for disc bulge with nerve compression or possibly a vascular cause. Iliac artery stenosis would be a possibility. Closing up his hip angle on the P3 can kink the artery, reducing blood flow to the legs and is a cycling specific issue causing this uncommon problem.

First post here, 21 years of working as a Sports Physiotherapist and 15 of doing bike fit.
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