Fifty-three years with USAA here and I agree that they've built their business reputation on long term reliability, and excellent service not low interest loans. Over the years since I first became a member in 1967, they're grown and improved by broadening their services tremendously and costs have always been reasonable. In all my years with USAA I have never had a claim denied or felt I've been short changed.
I also agree with previous posters that a motorcycle is not an essential investment, at least for the vast majority of Americans. Lending institutions with a narrower focus might reasonably offer lower interest rate loans for recreational vehicles - motorcycles, ATVs, jet skis, and snowmobiles.
If you're comfortable with the lender's terms then accept their contract, understanding, as others have indicated, it will not be your motorcycle until it's paid for. You may also discover that, should you decide to sell or trade the machine without keeping it for the best part of the loan term, you may well owe more to the lender than the retail value of the machine.