Wanting a beam rack so that I can occasionally take my rack trunk with a DSLR on my road bike. Usually I just take a pocket camera that fits in my jersey pocket.

Right now I have a mountain bike with a full size Blackburn rack and a large padded trunk, for when the main objective of the outing is photography. It can swallow my 50D with a 70-300 attached and has room to spare.

Port Bolivar by Yo Spiff, on Flickr

I'm going to be doing some longer road rides this year, in scenic areas where having the DSLR along would be nice. Thinking of a beam rack. If it could hold my current trunk bag, great, but a slightly smaller trunk bag would also do if that is necessary. It does not have to hold the camera with the big zoom attached, just a more modest 18-135, along with the roadside emergency items normally in my seat pack. Here's what I want to carry it on:

Celeste by Yo Spiff, on Flickr

I browsed around on Amazon, Performance & Nashbar. Many of the beam racks have negative reviews regarding clamps that don't hold. Any recommendations or feedback? Thanks.