1" threaded headset
I'm hoping you can me help me out.
I have an old Rock Hopper mountain bike, about 15 or 16 years old, that uses a 1” threaded headset which needs replacing. I have found two types of 1” threaded headsets. One has a 26.4 crown race and the other a 27 crown race. How do I determine which one I need, or does it matter? I haven't found any markings on the headset on there now.
1 bike 2 many.
You'll need to remove your fork and remove the fork crown race from it. Then either measure the ID of the race, or the OD of the fork crown. It will either be the 26.4 or the 27.0mm.
26.4 is the more common. I believe the 27.0 was mainly used on older (80's and beyond) Japanese bikes.