Bike Fit for Comfort, Not Just Speed

Most 'this bike doesn't fit me' complaints trace back to saddle height, not frame size. Too low and you lose power and stress your knees on the downstroke; too high and your hips rock side to side to reach the pedals, which shows up as saddle soreness and lower back fatigue on longer rides.

A reasonable starting point: seated, heel on the pedal at the bottom of the stroke, leg should be very nearly straight without locking out or rocking the hip. Switch to the ball of your foot for actual riding and there'll be a slight, natural knee bend at full extension.

Saddle fore-aft position affects where your power goes. Too far forward loads the front of the knee more; too far back can put more strain on hamstrings and lower back over long rides. A common reference point: with cranks level, your forward knee should sit roughly above the pedal spindle — treat it as a starting point to fine-tune from, not a rule.

Bar rotation is the most overlooked adjustment on a mountain bike. Too much upward rotation puts pressure on the heel of your palm; too much downward rotation pushes weight onto your fingers and wrists. Small changes here — a few degrees at a time — often fix wrist and hand numbness faster than a different grip or glove will.

Reach (effectively, stem length and bar sweep together) is worth adjusting before assuming a frame is 'the wrong size'. A shorter stem or a bar with more backsweep can meaningfully change how stretched-out a cockpit feels without touching the frame at all — often the cheapest fix available for a bike that otherwise fits well.