bikerboysam1 Posted December 3, 2005 Report Share Posted December 3, 2005 (edited) A few people have asked me recently how to fit a headset and how to determine what stem size you need, so this post is for them and also anyone else who needs help...... Is it possible to install a headset yourself without expensive tools? Well, yes it is, but I would not advise this, unless you are very familiar with how to do it, and you are very careful. This is because if a headset is installed imcorrectly, this can damage the headset cups and the frame. How do you adjust a headset? Before installing the fork a threaded piece called a star-nut is pressed into the top of the steerer tube. A top cap and bolt assembly is threaded into the star-nut. The top cap is designed to fit on top of the stem so that when it is tightened it compresses the stem towards the headset, effectively adjusting the preload on the bearings. Once the preload is correct, the clamp bolts on the stem are tightened and you are ready to go! How do I determine what size I need when shopping for a stem? Most important is the stem clamp diameter ( A ). The stem clamp on a threadless stem is one of 3 sizes: 1", 1 1/8", 1 1/4" or 1 ½”. By far, the most common size is 1 1/8", used on almost all bikes including many road bikes. Stem Clamp Diameter ( A ) Measure the outside diameter of the fork's steerer or the inside diameter of the stem. Use the following table to convert the size you measured on your bike to the actual size to order. Stem interior diameter / fork outer diameter --- Stem/Headset/Fork size to order 1 inch or 25.4 mm --- --- 1" 1 1/8" or 28.6 mm --- --- 1 1/8" 1 1/4" 31.8 mm --- --- 1 1/4" Handlebar clamp diameter ( B ) Virtually all bike stems use the same handlebar clamp diameter, therefore any bike stem can usually be used with any mountain bike handlebar. Stem Extension Length ( C ) The stem extension (along with the extension angle) determines the reach of the bike - how far you must reach to grasp the handlebars and brakes. If you're happy with the fit of your bike, simply measure your existing stem and order the same size. Ordering a slightly longer or shorter stem will change the fit of your bike, either putting you in a more aerodynamic, aggressive position or upright, relaxed position respectively. Usually, mod bikes are fitted with longer stems as they are smaller, and lower down. Rise Angle ( D ) The extension angle of the stem is purely a matter of comfort. A mod rider would usually prefer a stem with a bit of rise, while a stock rider would probably prefer a flatter, lower stem. Hope i have made things more clear for people, Sam Edited December 3, 2005 by bikerboysam1 Quote Link to comment Share on other sites More sharing options...
spode@thinkbikes Posted December 3, 2005 Report Share Posted December 3, 2005 I have "oversized" handle bars and my stem had to be oversized in order to compensate for them. Is that worth mentioning? Quote Link to comment Share on other sites More sharing options...
Dan6061 Posted December 3, 2005 Report Share Posted December 3, 2005 Have you not noticed the 'Help for the Newbies' thread? (Y) Quote Link to comment Share on other sites More sharing options...
bikerboysam1 Posted December 3, 2005 Author Report Share Posted December 3, 2005 Have you not noticed the 'Help for the Newbies' thread? :- Ohhhh, Well i'm sorry then (Y) :) Quote Link to comment Share on other sites More sharing options...
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