I initially bought a flimsy rack that is a clone to the Bell rack they sell at Walmart or Target. It developed a hairline crack at the knee joint between the post and the bike carrier arm the first time I used it. Luckily I was not on the freeway where I could have caused a terrible accident. As a structural engineer, I made some calculations and determined that 1.25" x 1/16" tubing is stressed too highly. I would suggest not buying a 4-bike rack for 1.5" receiver. The stresses are simply too high, and the consequence of failure could be a serious accident in addition to losing bikes.
The Allen rack is approximately twice as strong (section modulus) as the Bell rack, being made of 2"x 1/16" square tubing, assuming the steel grade is the same. It easily supports me (150 lbs) with very little deflection. After buying the rack, I saw on the internet that one reviewer said his Allen rack failed when one of the 3/8" bolts shear off. It was not this rack, but a previous design. This concerned me, so I made a structural calculation on the rack and the 3/8" pins. The most highly stressed pin, the pin holding the knee joint between the post and bike carrier is well under the allowable stresses. The weakest component is the tearout stresses through the hole that that pin goes through. Although it would seem it would be prudent to make that stronger, that part is still 66% of the allowable stress. Not sure why they cheaped out on a little bit more steel.
I would suggest checking the pins regularly for nicks and cracks, since the stress concentrations would severely weaken the pin. Maybe buy some extra pins from Allen so that you wouldn't be tempted to use a damaged pin. Also, install the rack so that the bolts are tight and the threads are outside the faying surfaces. Bolts are weakest at the threads due to high stress concentrations.
Functionally, this rack is good. I agree with the other reviews.
Some racks are a lot more expensive and is better quality and has more features. But the most import criteria in my book is that it is structurally sound. This Allen rack fits that bill for structural strength and a good balance between function and value.
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