We are going to labor this slightly, because it is the sort of thing most sites tidy away.
Horizon’s own product specification page: max user weight 300 lb.
The Amazon listing for the same machine:“a max user weight of 350 pounds”, stated in the listing copy.
They cannot both be right, and a 50 lb discrepancy on a load-bearing specification is not a rounding difference. Retailer listings are transcribed by people who are not engineers and get edited over a product’s life, so the manufacturer’s figure is the one to trust.
Treat this bike as a 300 lb machine.If you are near either figure, the sensible move is a different bike entirely — two machines on this site publish 450 lb at a lower price, with no ambiguity attached.
We flag it because it is a useful general lesson: when two published sources for the same product disagree, that is information about how much confidence any single published figure deserves.