We_are_Stevo":23c51q90 said:
FMJ":23c51q90 said:
Many (most) here will advise against using one of those steerer tube extenders in a threadless set-up (myself included). They are made for using a threadless stem in a threaded headset set-up, where the threaded top race and lockring take care of the bearing preload and clamping pressure. In a threadless system, the preload/clamping pressure on the bearings is maintained by clamping the stem to the steerer. With one of those extenders, the preload/retention is supported by the quill in the extender. They can and will twist/work loose under strain, sometimes with catastrophic results. Bottom line, they're your teeth, but it's really just a skint, bodge work-around to the proper solution.
Sorry, but what a load of tosh!
Interesting that. Initially I was 100% with FMJ - as I understood the original application of these things was for threaded forks.
But thinking it through and based on my own made bodge converters and extenders I've delibrately done just what FMJ says would result in an accident. Put a converter / extender to keep the damn threaded headset from loosing it's tightness by making it a A-head aswell (ie. loads of spacers etc. to butt against the threaded headset top lock-nut). It worked without issue, was solid, and dependable, and for all purposes I believe the thread on the fork column may as well not have been there at all in terms of load or strain bearing.
In engineering speak, it was crap before, and was fixed with an A-head extender. Before I get shot down, I agree it was not elegant or DIN or ISO or BSI or ANSI standard blah blah blah but it is a sufficient substitue for the real deal.
So, the pre-load required on a A-head headset must be minimal compared to the force keeping the extender locked in the fork column. If it wasn't, you wouldn't be able to turn the handlebars and fork to steer.
Similar to a normal stem, there must be a proper installation of the extender with sufficient length inserted in the fork column (without dollops of grease or loose fitting) to create sufficient friction.
You will need to decide how much the extender should be tightened up like a quill stem to create such friction - some school of thought says not so much in order to save a top-tube in a crash....blah blah blah.
Personally, I like things yanked up as far as controls go....as FMJ correctly says to save teeth.
