Originally Posted by
silvercreek
You have me a little curious. What's the difference in a B67 and a B67? Did you possibly mean B66?
I think he meant B66 and B67. B66 is double rail but B67 is single rail. I'm not sure they ride any differently but the B67 will work with a post that has rails whereas the B66 requires a seat post clamp or a special doohickey to make it work with that style seatpost.