I took the Gazelle A-Frame out tonight and twice I had a major vibration in the front wheel when braking to a stop when I had the wheel turned. Seems as if the brake pads (good quality Kool Stop dual-compound) were grabbing the rim firmly and then braking free repeatedly. The brakes are nashbar long reach dual pivots, they appear to be tight and without any excess slop. The headset also appears to be adjusted well without any excess play in it (though I will double check that tomorrow as it has been known to loosen some). Rims are Campagnolo Omega 19 in silver anodized, non-machined rims. Is it simply the combination of the longer reach brakes along with the non-machined rims? I don't have a whole lot of experience with non-machined rims as all my other bikes have had Open Pros or similar rims. In any case, the Omega 19's never have been the smoothest in terms of brake performance, but this vibration is downright worrisome. Thanks!