Repair guides › Seat & Contact
Set saddle height
Holds the saddle and sets saddle height. Diameter must exactly match the frame (27.2, 30.9 and 31.6 mm are common; it is printed on the post). Slides into the seat tube; the seat clamp squeezes the tube onto it. The minimum-insertion line must stay inside the frame, and the post must reach below the top-tube/seat-stay joint. 27.2 mm is the most common size, so dropper and suspension posts are easy to find.
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Tools
- Ball-end hex key set (1.5–10 mm): Park Tool HXS-1.2 Professional L-Shaped Hex Set ($$)
- 1/4" click torque wrench (about 2–17 Nm) + bits: Pro Bike Tool 1/4 inch drive click torque wrench set (2.2–16.9 Nm) ($$)
- Tape measure + 6" steel ruler: Stanley 16 ft tape measure ($)
Compare Good, Better and Best for each tool
Steps
- See My Bike for your starting height from your inseam (LeMond: inseam × 0.883, measured from BB center to the top of the saddle along the seat tube).
- Heel check: in riding shoes, put your heel on the pedal at the bottom of the stroke. Your leg should be straight. Riding on the ball of the foot then gives a slight bend.
- Loosen the seat clamp, set the height, line the saddle nose up with the top tube, tighten.
- Never go above the minimum-insertion line on the post. The post must also reach below the top-tube/seat-stay joint. If the post has no mark, keep at least 2.5× its diameter inside the frame (68 mm for 27.2 mm), or the frame maker’s figure if it’s more (often 80–100 mm on aluminum frames).
- Ride 20 minutes. Hips rocking = too high. Knee pain at the front = too low.
- Change in 3–5 mm steps.
Torque
| Fastener | Torque |
|---|---|
| Seat clamp bolt | as marked on the collar (often ~5 Nm; some are lower) |
Diagram
Side view, chain side toward youSeatpost and saddle
Signs it needs doing
- Post slips down while riding
- Creak from the seat area
- Stuck post (corrosion)
Problems this fixes
Articles about this job
- The best first upgrades for a cheap bike (and what to skip): what I found as a beginner
- What size bike do I need? What I found as a beginner (height chart and fit check)