I’ve just fitted a new Thomson x4 stem, and very nice it is too. The instructions that come with the stem are rather ‘exacting’, for example, ‘leave no more than a 3mm gap from the top of the stem to the top surface of the steerer tube’, torque values are abolutes rather than a range and there are instructions as to the grade of sandpaper to use to remove burrs from the steerer, and to file a round profile on the top of the steerer! Normally I just stick the stems on and tighten them up!
Apart from a bit of filing on the top of the steerer tube to stop it bottoming out on the preload cap it all went smoothly but I also noticed that the instructions relating to headset preload caps are pretty specific too and state that the A dimension of a stem cap (the bit that sits inside the stem) must not exceed 29.7mm as it will stop the stem clamping onto the cap, and then goes on to talk about which design of Thomson stem cap can be used with different types of Thomson stems. It all seems rather overly exacting to me and I only had the pre-load cap that came with my Cane Creek S3 headset, so I used that. I was under the impression that you only used the cap for pre-loading and could even remove it once the stem had been tightened.
Everything seems to have pre-loaded and tightened up properly, should I worry that my pre-load cap may not meet Thomson’s specs.?
