Originally Posted by
Campag4life
As usual Merlin is correct and you are misinformed. Too many spacers above the stem clamp displaces the steer expander higher. This doesn't allow for the expander to reinforce the ID of the carbon steerer tube in the area of highest stress where the stem clamp bolts are torqued...or below where the lower edge of the stem clamp induces a stress riser due to handlebar torque applied by the rider.
I've been a stickler about CF steerer spacers and manufacturers tech data in other threads...but I'm starting to wonder just how precise this needs to be. (probably needs its own thread, really...)
For instance; Cannondale CF steerers. Due to the interface C'dale specifies NO spacers on top. Period. Yet the C'dale pro tour team bikes are pretty much all violating that guidance on their shiny Supersix Evos.
Other CF steerers, like Bontrager; 2-3mm above the stem, with a 5mm spacer. This is due to their interface.
Easton EC90; 7-8mm above, with an ugly honking 10mm spacer. Yet with their unique thread-in "bung", and the thickness of the CF steerer, why not 2-3? And, of course, pics of bike shop and team bikes routinely show "violations" of all these things. Aside from some Bontrager forks, there have not been a rash of steerer failures out there. (And Trek blamed FSA in the end, so there we go...)