Will a tapered fork fit a straight 1-1/8" head tube?
By Crankworthy · Published · Updated
No. A tapered steerer widens to 1.5 inches at the crown, and a straight 1-1/8" head tube has no room for it at the bottom. You need a straight-steerer fork, or a frame whose head tube is built to take a tapered steerer.
Why
Most modern mountain forks have a tapered steerer: 1-1/8" at the top, widening to 1.5" where it meets the crown. The wider lower section makes the front end stiffer.
A straight 1-1/8" head tube is the same diameter top to bottom. The lower bearing seat is simply too small for the 1.5" section of a tapered steerer, and no headset can change that.
Some frames use a 44mm straight head tube that can accept a tapered steerer with an external lower cup. If your frame has that, a tapered fork is possible — check the frame spec.
How to tell what you have
- Straight 1-1/8"
- The head tube looks the same width at top and bottom, and the fork steerer is the same diameter all the way down.
- Tapered
- The head tube is visibly wider at the bottom than the top.