Basic Principles of Bike Fitting: The Role of the Physical Therapist Matthew S. Briggs, PT, DPT, SCS, ATC

Transcription

1 Basic Principles of Bike Fitting: The Role of the Physical Therapist Matthew S. Briggs, PT, DPT, SCS, ATC School of Health & Rehabilitation Sciences, The Ohio State University; Improving People s Lives through innovations in personalized health care

2 Objectives By the end of this presentation you should be able to: Describe important, basic bike anatomy Describe common overuse injuries associated with cycling Understand basic principles of bike fitting to avoid and/or treat cycling injuries & help your patients/clients ride safer 2

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6 Terms to Know Saddle (vs seat) Reach: tip of saddle to center of handlebar Bottom Bracket Fore, Aft: bottom bracket to saddle Drop: saddle to handlebars The Drops: the lower level of handlebars 6

7 One position for a very long time! Cervical Extension Lumbar Flexion Injury Type of cycling Duration Intensity Mechanics History 7

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9 Cycling Injuries Sport of Repetition - Overuse rpm, 6 hour century ride 32,400 strokes PER LEG Any minor misfit causes MAJOR problems BIKE FIT IS KEY 9

10 (Wilber 1995; Clarsen 2010) 10

11 Risk Factors: Overuse Injury Males Miles/Week Low # of Gears Less Experience Females More training time/year vs. races Less time stretching 2x risk for neck/shoulder Other considerations: Poor lumbopelvic/ thoracic muscular endurance Improper Bike Fit 11 (Wilber 1995)

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13 Neck Injuries Cervical spine pain Headaches Radiculopathy Positioning / posture Thoracic musculature weakness Prolonged extension Deep cervical muscle weakness Helmet / glasses fit Bike Fit 13

14 Knee Injuries Anterior Knee Pain Iliotibial Band Syndrome Poor tracking Proximal stability weakness / lack of control Overuse / training errors Bike Fit Saddle position Shoe-pedal interplay 14 Clarsen 2010; Ellis 2007; Asplund 2004; Bailey 2003

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16 Low Back Injuries Lumbar pain Increased Pelvic/lumbar extension Iliopsoas inflexibility Bike fit Saddle inclination 16

17 Hand Injuries Median nerve Ulnar nerve 17

18 Groin / Pelvis Injuries Pudendal nerve palsy Between sacrotuberous & sacrospinous ligaments, at ischial tuberosity (stretched during pedaling) Increased pressure from saddle or nose of saddle 18

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20 Weight Distribution NO GOOD! 20

21 Cycling Biomechanics (and efficiency) Alter with changes to: Saddle Height Saddle fore/aft position Crank Arm Length Foot Position Cadence (revolutions / minute) Work Load (resistance or power) 21

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23 Examination: Interview: Cycling History Injury history Events?: recreational criterium century tours triathlons Shoe / Cleat / Pedal Orthotics Days / Week cycling Weekly Mileage Longest recent ride Typical speed Typical Cadence Changes to cycling routine 23

24 Examination: Interview: Cycling History Type of bike Type of use Recreational Triathlons Tours Cyclocross Track Mountain Injury History Time on Bike 24

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26 Physical Examination Functional tests: e.g. SFMA, FMS, unilateral testing Movement patterns Mobility vs. stability Leg length 26

27 Make the bike fit the body don t make the body fit the bike 27

28 Bike Fit Basics: Necessary Tools Bike Trainer Riser blocks (towels?) Goniometer Level (phone app?) Plumb line (tape measure?) Basic allen wrenches Patient/client need to bring anything they would wear on the bike! 28

29 Bike Fit Basics: Session At least 1-2 hours long.5-1 hour evaluation & history 1 hour dynamic bike fit on trainer Our bodies change so an annual fit should be part of training 29

30 Bike Fit Basics: Lateral View Saddle Fore/Aft Cervical Posture (check with cycling glasses/helmet on) Spine Posture (neutral spine) Be sure the bike is level: set level across axels Shoulder Angle Elbow Angle Wrist Angle Hip Angle Knee DBC ~30 Ankling Angle 30

31 Bike Fit Basics: Saddle Size The Ass-izer 31

32 Bike Fit Basics: Saddle Position Most important variable to get right Includes height, setback, tilt, and width Too low = anterior knee pain Too high = pain behind knee over stretching the hamstrings Saddle sores & crotch irritation-rocking pelvis Find balance maximizes patellar fulcrum, while not injuring it 32

33 Bike Fit Basics: Saddle Height Put bike on trainer & pedal for five minutes This helps you loosen up & find position Quick & Dirty Check: Unclip shoes & place heels on the pedals Pedal slowly & watch knee at bottom of stroke Shoes almost, but not quite lose contact with pedal 33

34 Bike Fit Basics: Saddle Set Back Setback (fore/aft)-you in relation to the bottom bracket Determined by femur length Knee center of rotation (COR) directly over pedal Long legs should move seat back Short legs should move seat forward Correct position: COR over pedal & ischial tubes on widest part of saddle 34

35 Why is Set-Back Important? Put the power of your leg into the pedal at the point in the crank circle when it does the most good To get maximum power the knee should be over the pedal axel First set seat height then adjust set-back 35

36 Bike Fit Basics: Optimizing Set-Back Measure Saddle Fore/Aft: plumb from knee to front of crank arm Seat too Forward: increased patelofemoral load Seat too Aft: patella becomes an ineffective fulcrum energy is wasted &stresses inefficient hamstrings 36

37 Bike Fit Basics: Saddle Tilt Tilt- should almost always be level If not something else is most likely wrong with the fit Pedal no hands & see if you slide forward 37

38 Bike Fit Basics: Knee angle Dead Bottom Center (DBC) Knee DBC ~30 Changes with load and RPMs Knee angle vary between dynamic fitting 38

39 Bike Fit Basics: Torso Angle Most riders are Euro racers on brake hoods Old & Young riders Fitness Enthusiasts 50 Be sure all three grips are useable/comfortable 39

40 Bike Fit Basics: Elbow/Wrist Position Handshaking position (wrist in neutral) Adjust hoods to achieve this position Should be level with top bar Or adjust so the end of the bar points to the center of the seatstay Elbows at ~15 40

41 Bike Fit Basics: Shoe/Cleats Last aspect to consider Unless they are new Can eliminate hip, knee, and foot pain Ball of foot over pedal axel Speed Play SPD Look 41

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43 Symptom Likely Cause Try Scooting forward on seat Scooting back on seat Lower back hurts Stem may be too long so you pull yourself forward as you ride; saddle nose may be tipped down too much Stem may be too short so you feel cramped and push yourself back; saddle nose may be tipped back; saddle may be too far forward on the rails Stem too low or too long; must strain back to reach bars; or seat may be too high, causing rocking when pedaling Install a shorter stem; level saddle Install a longer stem; level the seat and center it on the rails; move your seat back Try raising the stem/handlebars; still hurts? try shorter stem; check and adjust seat height Neck hurts Stem too low; must crane neck to see Raise the stem/bars Hands hurt Front of knee hurts Stem too low; too much weight on hands; saddle may be pointed down Seat too low and/or too far forward, straining knees Raise the stem/bars; level saddle Raise seat; may need to move seat further back as well Back of knee hurts Seat too high, over-extending leg Lower seat Numb bum Achilles tendon hurts Too much weight on the seat; may need to slide back a little on the seat. Try to sit such that you feel the weight on your sit bones rather than the front or center of your crotch Pedaling too much on your toes; cleats too far forward on your shoes; feet may not be forward enough over the pedal Lower handlebar position; check seat height as it may be too high; May need to try another brand of shorts and or seat; lose weight Keep the balls of your feet over the pedals when you re pedaling; move cleats back. 43

44 Final Thoughts Focus on injury prevention, movement dysfunction, & performance. Detailed medical history. Physical examination = mobility, stability, strength, etc. Biomechanical & biometric measurements. Many different fit systems Takes practice/training 44

45 Some good references 45

46 Thank you! Matt Briggs PT, DPT, SCS, ATC 46

47 sportsmedicine.osu.edu