Headset - Mountain Bike Zen
Types of Mountain Bike Headset
There are several types of headset for mountain bikes. Older bikes had a threaded headset and the steerer will be 1 inch in diameter. A threaded steerer will have a threaded fork and the top of the steerer tube will have a screw on nut. Loosening and removing these will require two large bike spanners. Replacement parts are still available for these although they are no longer used in most new bike production.
It is much more common for modern bikes to have unthreaded headsets. The forks will have no thread to screw onto (the tube will be smooth) and usually are attached by using a bolt through he top of the stem and top cap into a star nut which is wedge inside the inner part of the fork steerer tube. Most forks will come with the steerer tube integrated although sometimes these can be fitted seperately.
It is important to know which type of headset you can use with your frame before buying a replacement. Your bike spec should state the diameter of steerer tube and what type of headset is included as standard, some research will help find out if other types of headset can be used.
Replacing a headset is a little tricky and is best done with specialist bike tools. Take a good look at the set up before removing so you can see how it should look once replaced. You need to remove your stem and bars, so loosen the top cap and the stem and rest your bars somewhere safe, it may be best to remove the grips and brake levers so you can put it completely out of the way. Keep the top cap somewhere safe if you are going to replace it. Slide out the fork steerer tube from the head tube of the mountain bike frame and keep all loose parts safe. Remove the cups - if you need to you can use a flat headed screwdriver and tap from the inside of the tube using a hammer on the screwdriver. This may take a little while depending on how long the cups have been wedge in and what condition the head tube is in. Clean well and use a little grease before replacing with a new or reconditioned headset.
If you need to use a hammer to get the new cups in make sure you protect the hardware by using a flat wedge of wood or similar between the hammer and the hardware.
Usually a full headset replacement will not be necessary unless the old one is damaged, but you will probably need to replace or recondition the bearings every couple of years - the frequency wiull depend on how often you use the bike and how much abuse it has taken. Bearings can be cleaned, thoroughly dried and greased. You can usually tell simply by rotating them whether they will need replacing, a rough or uneven feel with uneven vibration will usually mean a replacement is needed.