Dropper Post Length Calculator
Seat post clamp to saddle rails, at pedalling height
Seat post clamp to the first obstruction in the frame
Measurements changed – press Recalculate to update.
Your recommended post will appear here.
Want to know how long a dropper post you can fit on your bike? Choose your seat post diameter, enter two measurements, and the calculator will tell you.
Step 1 – Measure your ride height. This is your current saddle height: the distance from the top of your seat post clamp to the middle of your saddle rails, with the saddle at your normal pedalling height.
Step 2 – Measure your insertion depth. This is the distance from the top of your seat post clamp to the first obstruction or bend in your frame. Remove your seat post and slide a rigid rod or tape measure into the frame until it stops.
Before you enter your insertion depth, take 10–15mm off it. Depending on the frame design, inserting a dropper to its maximum depth can bend the cable too sharply for the post to work properly.
Step 3 – Enter both measurements in millimetres and press Calculate.
The travel of every OneUp dropper post can be reduced by 10mm or 20mm using the travel reducing pins included in the box. If your result shows a shorter drop than the post it names – for example "200mm drop" for a "V3 Dropper Post 210mm" – fit the pins to set the post to that drop. Learn how to adjust your dropper's travel.