· Hugo · Health · 3 min read
Lower Back Pain After Cycling? (Stem Length vs Saddle Height)
Stop the ache. If your lower back hurts after every ride, the culprit is likely a poor bike fit. Learn how to adjust your saddle and stem to eliminate back pain for good.
You finish a two-hour ride, and as soon as you stand up off the bike, your lower back feels stiff, tight, or even painful.
Lower back pain (LBP) is the #1 overuse injury in cycling. While many riders assume they just have a “weak back,” the truth is that your bike is likely forcing your back to do work it wasn’t designed for.
In this guide, I’ll break down the two most common mechanical causes of back pain—Saddle Height and Stem Length—and how you can adjust them at home to ride pain-free.
1. Saddle Height: The “Hip Rock” Problem
If your saddle is too high, your legs have to reach too far at the bottom of the pedal stroke. To get that extra reach, your hips have to rock back and forth on the saddle.
This “hip rocking” puts massive strain on the lumbar vertebrae and the muscles connecting your spine to your pelvis.
The Fix:
- Lower your saddle by 5mm at a time.
- The Test: Have a friend watch you from behind while you pedal on a trainer. Your hips should remain stable and level; if they are dipping to one side as the leg extends, the seat is too high.
2. Saddle Fore/Aft: The Balance Point
If your saddle is too far back, you have to reach further forward to grab the bars, stretching your lower back muscles like a rubber band.
The Fix: Use a plumb line (or a piece of string with a weight). With your pedals at the 3 o’clock and 9 o’clock position, the string should fall from the front of your kneecap directly through the spindle of your pedal.
3. Stem Length & Handlebar Reach
If your handlebars are too far away (long stem) or too low (slammed stem), your spine has to curve excessively to reach the controls. This “over-stretching” of the back leads to muscle fatigue and sharp pain.
The Fix:
- Shorten the Stem: Swapping a 110mm stem for a 90mm stem can significantly reduce the strain on your lower back.
- Flip the Stem: Most stems can be installed “upside down” to give you a positive rise, which brings the handlebars higher and closer to you.
4. The Core Strength Connection
Even with a perfect bike fit, if your core muscles (abs and obliques) are weak, your lower back has to take over the job of stabilizing your torso while you pedal.
The Fix: Incorporate 10 minutes of “Planks” and “Bird-Dogs” into your weekly routine. A strong core acts as a support beam for your spine, taking the load off the lower back.
Diagnostics: Where does it hurt?
| Symptom | Likely Fit Issue | Quick Fix |
|---|---|---|
| Aching/Burning on both sides | Bars too low or too far away | Shorten stem or add spacers. |
| Sharp pain on one side | Saddle too high (Hip rocking) | Lower saddle by 5-10mm. |
| Tightness at the base of the spine | Saddle pointed too far UP | Level the saddle or tilt nose down 1 degree. |
Cycling Back Pain FAQ
| Question | Answer |
|---|---|
| Should I stop riding until the pain goes away? | If it's a dull ache, short easy rides on a flat saddle can actually help 'flush' the muscles. If it's a sharp, shooting pain (sciatica), stop immediately and consult a physical therapist. |
| Can a shorter crank arm help? | Yes. Shorter cranks reduce the range of motion at the hip, which can prevent the lower back from 'tucking' at the top of the pedal stroke (known as butt wink). |
| How do I know if my stem is too long? | When you are in a riding position and look down at your front wheel hub, the handlebar should ideally 'hide' the hub from your view. If the hub is visible behind the bars, your stem might be too long. |