Thule Prologue vs. Echelon. Crap vs. Quality.
I've got a reasonably heavy 6 inch travel bike, about 32 lbs. I purchased a Thule Prologue roof rack thinking it would be adequate for my rig. This rack was a total mess. I was too tempted by the low price (about $100 MSRP) and figured its a Thule rack, its gotta be decent. It was wasn't. My bike shook back and forth constantly at any speed. I could hear the damn thing rocking back and forth on the highway and every where else. In the process it loosened the bolts the held the head of the rack on. I was constantly tightening the bolts to the point where they became stripped. I was more and more cautious overtime I had my bike on my car.
The head is garbage, held to the crossbar by a flimsy u-bolt and a plastic body. The rest of the tray was a wobbly, thin metal that I could twist with my bare hands. I returned the Prologue after a few weeks and got an Echelon instead. Holy crap what a difference.
I almost lost faith in Thule until I got the Echelon. The head, tray and everything is solid friggin' metal. Thicker, heavier, stronger and stiffer in every way. It was only an extra $50 and my god what a difference. The thick metal that makes up this rack holds my bike almost completely still on everything from highway speeds to bumpy trail heads. I'm confident this rack will hold a heavier DH/FR bike without and issue. I also use 20 mm thru axle adapter with it and it does't hurt the stability at all.
Unless you have a feather weight bike. Do no get a Prologue. Its a cheap rack. If anyone from Thule is reading this, please discontinue the Prologue. You make great gear, just not this one.
That is all.