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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; OSU Sports Medicine
OSU Sports Medicine
Objectives
By the end of this presentation you should be
able to:
Describe important, basic bike anatomy
Describe common overuse injuries associated withcycling
Understand basic principles of bike fitting to avoidand/or treat cycling injuries & help your patients/clients ride safer
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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
:
One position for a
very long time!
Cervical Extension Lumbar Flexion
Injury
Type of cycling Duration Intensity Mechanics HistoryCycling Injuries
Sport of Repetition -
Overuse
80-90 rpm, 6 hour century ride
32,400 strokes PER LEG
Any minor misfit causes MAJOR problems
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Risk Factors:
Overuse Injury
Males
Miles/Week
Low # of Gears
Less Experience
Females
More training time/year vs. races
Less time stretching
2x risk forneck/shoulder
(Wilber 1995)
Other considerations:
Poor lumbopelvic/ thoracic muscular endurance
Neck Injuries
Cervical spine pain
Headaches
Radiculopathy
Positioning / posture
Thoracic musculature weakness
Prolonged extension
Deep cervical muscle weakness
Helmet / glasses fitOSU Sports Medicine
Knee Injuries
Anterior Knee Pain
Iliotibial Band Syndrome
Poor tracking
Proximal stability weakness / lack of control
Overuse / training errors
Bike FitSaddle position
Shoe-pedal interplay
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Low Back Injuries
Lumbar pain
Increased Pelvic/lumbar extension
Iliopsoas inflexibility
Bike fitHand Injuries
Ulnar nerve
Median nerve
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Groin / Pelvis Injuries
Pudendal nerve palsy
Between sacrotuberous & sacrospinous ligaments, atischial tuberosity (stretched during pedaling)
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Weight Distribution
Cycling Biomechanics
(and efficiency) Alter with changes to:
Saddle Height
Saddle fore/aft position
Crank Arm Length
Foot Position
Cadence (revolutions / minute)
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
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Examination: Interview: Cycling History
Type of bike
Type of use
Recreational
Triathlons
Tours
Cyclocross
Track
Mountain
Injury History
Time on Bike
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Physical Examination
Functional tests
:
e.g. SFMA, FMS, unilateral testing
Movement patterns
Mobility vs. stability
Leg length
“
Make the bike fit the body…
…don’t make the body fit the
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Bike Fit Basics:
Necessary Tools
Bike
Trainer
Riser blocks
(towels?)
Goniomete
r
Level
(phone app?)
Plumb line
(tape measure?)
Basic allen wrenches
28
Patient/client need to bring anything they would wear on the bike!
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
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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 Ext @ DBC ~30° Ankling Angle
Bike Fit Basics:
Saddle Size
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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
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 strokeOSU Sports Medicine
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 onWhy 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
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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 fulcrumBike Fit Basics:
Saddle Tilt
Tilt- should “almost” always be level
If not something else is most likely wrong with the fit
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Bike Fit Basics:
Knee angle
Dead Bottom Center (DBC)
Knee Ext @ DBC
~30°
Changes with load and RPMs
Knee angle vary between
20-40°
Bike Fit Basics:
Torso Angle
Most riders are 30-50°
Euro racers 30-35° on brake hoods
Old & Young riders 35-45°
Fitness Enthusiasts 50°
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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
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
Symptom Likely Cause Try…
Scooting forward on seat Stem may be too long so you pull yourself forward as you ride; saddle nose may be tipped down too much Install a shorter stem; level saddle Scooting back on seat
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
Install a longer stem; level the seat and center it on the rails; move your seat back
Lower back hurts
Stem too low or too long; must strain back to reach bars; or seat may be too high, causing rocking when pedaling
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 Stem too low; too much weight on hands; saddle may
be pointed down
Raise the stem/bars; level saddle
Front of knee hurts Seat too low and/or too far forward, straining knees 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
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
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
Achilles tendon hurts
Pedaling too much on your toes; cleats too far forward on your shoes; feet may not be forward enough over the pedal
Keep the balls of your feet over the pedals when you’re pedaling; move cleats back.
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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
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