THE WHY BEHIND THE NUMBERS

The Lemond method is the most-cited saddle-height formula. Greg LeMond popularized it: measure your inseam (pubic bone to floor, in cm), multiply by 0.883, and you get your saddle height in millimetres from the bottom bracket to the top of the saddle. Why 0.883? It corresponds to a knee angle of about 25-30 at the bottom of the pedal stroke · the range most bike fitters target for both comfort and power. **Limitations:** - It assumes average hamstring flexibility - It assumes a moderate pedaling style - It doesn't account for cleat stack height or shoe thickness **How to refine it:** 1. Start with the Lemond number 2. Adjust 2-3mm at a time 3. Test 1-2 weeks before changing again 4. The knee-angle method (27-30 at BDC) is a good sanity check 5. If you have very tight hamstrings, drop the saddle 5-10mm below Lemond

Saddle-to-bar drop is the difference in height between your saddle and your handlebars. It's the single biggest factor in how aggressive (or comfortable) your bike feels. **The 1.09 method:** - Measure your inseam in cm - Multiply by 1.09 · this is your saddle-top to handlebar-grip-line distance - Subtract your saddle height · that's your maximum comfortable drop - A road bike with 7-9cm of drop is typical - An endurance bike has 5-7cm - A TT bike has 10-15cm **Flexibility correction:** - Poor flexibility: cap your drop at 70% of calculated - Average: 100% - Good: 110% - Excellent (can do a full bridge): 120% If your bike has more drop than this, raise the stem (spacers) or get a frame with shorter head tube.

Stem length compensates for frame reach. A longer stem stretches you out, a shorter stem brings the bars closer. Most riders under-estimate how much 10mm of stem change affects handling and comfort. **A simple formula:** For a typical 56cm road frame with reach 386mm: - 175cm rider · 100mm stem - 180cm rider · 110mm - 170cm rider · 90mm - 165cm rider · 80mm **When the frame is bigger/smaller:** - 10mm longer frame reach · 4mm shorter stem - 10mm shorter frame reach · 4mm longer stem This keeps the effective reach to the bars constant. **Test it:** - Too long? You feel stretched, hands numb, neck aches - Too short? Bars feel like they're in your lap, climbing is uncomfortable - Right? You can hold the drops for 60+ minutes without shifting

Crank length is the only "fit" number you can't change without buying new parts. That makes it disproportionately important. **The rule:** - Inseam (cm) 2.16 = recommended crank length (mm) - Round to the nearest 2.5mm - Common lengths: 165, 167.5, 170, 172.5, 175 **Why 2.16?** It corresponds to roughly 19% of inseam. Longer cranks give more leverage but force your hip through a bigger arc (can cause knee issues); shorter cranks reduce hip range of motion but you lose top-end power. **Practical advice:** - Most riders: stay within 2.5mm of the recommendation - Older riders or those with hip mobility issues: try 2.5-5mm shorter - Larger riders (taller than 185cm): consider 175mm cranks - Smaller riders (under 165cm): 165-170mm cranks **Don't sweat the 2.5mm step.** Stiffness, q-factor, and pedal platform matter more.

Every modern frame lists stack and reach in its geometry chart. These two numbers · measured in millimetres · describe your position on the bike more completely than any other spec. **Definitions:** - Stack: vertical distance from the bottom bracket to the top of the head tube - Reach: horizontal distance from the BB to the center of the head tube top **Why they matter:** - They are size-independent (in theory, a 56cm and 58cm of the same model have proportional stack/reach) - They predict your position more accurately than the nominal frame size - They let you compare frames from different brands accurately **The stack-to-reach ratio (S/R):** - 1.40 = very upright (touring, hybrid) - 1.45 = endurance road - 1.50 = balanced road (most road bikes) - 1.55-1.60 = aggressive road - 1.65+ = TT / triathlon **Sizing across brands:** If you're between sizes, prioritize stack first (use spacers to fine-tune reach), then reach. Most riders prefer slightly less reach and slightly more stack · it's easier to make a "long" bike shorter than to stretch a "short" bike.

Head tube length determines how much spacers you can fit under your stem · and therefore how high or low you can set your bars. **Rule of thumb:** - 100-130mm head tube: aggressive (race) - 130-160mm: balanced - 160-200mm: endurance / comfort - 200mm+: touring **Why it varies so much:** A larger frame needs a longer head tube to maintain the same stack-to-reach ratio and head tube angle. So a 56cm frame might have a 140mm head tube while a 61cm has 200mm. **Practical:** If you want an aggressive position, look for shorter head tubes (which lets you run a long stem with minimal spacers). If you want comfort, longer head tubes (or a frame with high stack) is the way.

A professional bike fit is the single best thing you can do for comfort and performance. Here's what to expect at each level. **Level 1 · Basic position check (30-60 min, often free with bike purchase):** - Saddle height and setback - Stem length and height - Quick observations about knee, back, and shoulder alignment - Tools: plumb line, goniometer, eyeballing **Level 2 · Dynamic fit (90-120 min, $200-400):** - Saddle height and setback measured under load (pedaling) - KOPS (knee-over-pedal-spindle) check - Cleat position - Bar reach and drop - Tools: motion capture or video, pressure mapping sometimes **Level 3 · Full Retl-style fit (2-3 hours, $400-600):** - 3D motion capture of every joint - Pressure mapping on saddle and feet - Saddle selection from a demo library - Cleat customization - Pedal stroke analysis - Tools: Retl, Gebiomized, or similar systems **What to bring:** - Your bike (or a bike you can borrow from the shop) - Cycling shorts - Your normal cycling shoes and pedals - A list of any pain you've been feeling **What to ask:** - "What did you measure and why?" - "Show me the data before and after." - "What changes are critical, and what can I experiment with later?"

Cleat position is the most under-appreciated fit dial. Three independent adjustments: fore-aft, stance width, and rotation. **Fore-aft (long axis of foot):** - Default: ball of foot over pedal spindle - Move cleats BACK if you have knee pain in front of knee (over-flexion) - Move cleats FORWARD if you have knee pain in back of knee (over-extension) - Range of motion: 5-10mm total **Stance width (medial-lateral):** - Default: as close to natural foot angle as possible - Wider stance: better for bow-legged riders, can relieve inside knee pain - Narrower stance: better for knock-kneed riders, can relieve outside knee pain - Most riders: 5-7mm wider than the pedal spindle **Rotation (float):** - Most pedals: 4-6 of float per side - Set cleats to neutral (no tilt) first - Adjust to match your natural foot angle (most people's feet naturally toe out 3-5) - Excessive rotation under load indicates a fit issue, not a cleat issue **Tools you need:** - A piece of cardboard or carpet to find natural foot angle - A friend to photograph from behind while pedaling - Patience · small adjustments compound over weeks

Pain at the front of the knee (around the patella, the kneecap) is the most common cycling-related knee pain. The medical name is patellofemoral pain, but cyclists usually call it "anterior knee pain." **Most common causes:** 1. **Saddle too low** - Forces the knee to track over a sharper angle - Increases patellofemoral compression - Fix: raise saddle 2-3mm at a time until pain eases 2. **Saddle too far forward** - Same effect as low saddle - Fix: move saddle back 5mm at a time 3. **Cranks too long** - Forces your hip through too much range - Fix: try 2.5-5mm shorter cranks 4. **Cleats too far forward** - Effectively the same as moving the saddle forward - Fix: move cleats back 3-5mm **When to see a doctor:** - Sharp, sudden pain - Pain that doesn't ease with rest - Swelling - Locking or catching - Pain at rest **What to try first (in order):** 1. Raise saddle 2-3mm 2. Wait 1-2 weeks 3. If no relief, move saddle back 5mm 4. Wait 1-2 weeks 5. If no relief, try shorter cranks

Lower back pain is the second most common cycling complaint. It usually has one of three causes · or a combination. **Cause 1: Bars too low or too far** - Forces you to rotate your pelvis posteriorly (tuck under) - Lumbar spine rounds - Disc compression - Fix: add 10-20mm of spacers, shorten stem 10mm **Cause 2: Saddle tilt nose-up** - Pushes you forward on the saddle - Hands bear more weight - Core has to work harder - Fix: level the saddle (0 to -1 nose-down) **Cause 3: Weak core / poor flexibility** - Riding position is sustained; core has to hold you there - Tight hamstrings pull on the pelvis - Fix: 10 min/day of core work + hamstring stretches **The saddle-bar drop budget:** - Most riders: 7-9cm drop - Older riders or back-pain sufferers: 5-7cm - Younger, flexible riders: 9-12cm **Don't ignore the warning signs:** - Numbness in the saddle area - Pain that radiates down a leg - Pain that wakes you up at night These need a medical professional, not a fitter.

Flexibility is the most under-measured variable in bike fit. A "correct" saddle height for a flexible rider is 5-10mm too high for a stiff rider. Here's the science. **Why flexibility matters:** - Saddle height depends on how far your hip can flex before your pelvis tilts - Bar drop depends on how far your upper body can extend - Cleat position depends on how much ankle dorsiflexion you have **Test 1: Hamstring flexibility (sit-and-reach)** - Sit on the floor, legs straight - Reach forward - Palms past toes: excellent - Fingertips to toes: good - Fingertips to mid-shin: average - Can't reach past knees: poor **Test 2: Hip flexor tightness** - Lie on your back, pull one knee to chest - Can the other leg stay flat on the floor? - If not: tight hip flexors, will cause back pain in aggressive position **Test 3: Ankle dorsiflexion** - Kneel facing a wall, foot 10cm away - Can your knee touch the wall without lifting your heel? - If not: limited ankle mobility, will push saddle too high in your head **What it means for your fit:** - Poor: add 5-10mm of spacers, raise saddle 5mm - Average: standard fit - Good: standard to 5mm lower / 5mm longer stem - Excellent: aggressive fit possible (race geometry)

Aero gains come from a more horizontal torso. But a more horizontal torso means more strain on the lower back, neck, and wrists. Here's the framework. **The energy equation:** - Every 1 lower torso · 2-3 watts saved at 30+ km/h - Every 1 lower torso · +2-3% back/neck strain - The break-even depends on your race duration and pain tolerance **For 30-60 min events (criteriums, TTs):** - Aggressive position pays off - Accept some discomfort - Max out your current flexibility **For 2-4 hour events (road races, fondos):** - Balanced position is the sweet spot - Comfort over the last hour matters more than speed over the first - Stay within 70-80% of your "stretch" **For 6+ hour events (ultras, tours):** - Endurance position is the only one that works - Comfort and durability trump aerodynamics - You cannot "push through" 6 hours of pain **Practical testing:** 1. Hold your most aggressive position in a trainer 2. Time how long before you have to shift 3. Subtract 20% for outdoor conditions 4. That's your max position duration If your race is longer than that, raise the bars 5-10mm.