If you find one, let me know!
I use and enjoy the twofish, but wouldn't call it "sturdy." It'll hold the light alright, and I have no fear that it'll let go - but it jostles around a bit.
I have the Fenix as well. It is more rigid, but can be nudged out of place. It's not heavy, but is bulky. And it rattles a bit.
I would love a low-profile aluminum mount, but the one shop I contacted to build me one never got back to me after I sent him a sketch.
I just came across 2 UltraFire aluminum bike mounts - one for 22-25mm lights and one for 25-28mm. At 10 bucks a pop on ali or 7ish on the bay, those might be worth cheking in to.
Anybody tried one yet?