The seat tube on our T-50 is a 29.8. This is now a not common size. The stock post has poor adjustment for angle and I'm thinking of a new one. I also want a Thudbuster for the little engine that could at my back. We ride in an urban environment and there's too many bumps and cracks to call though I will continue too call the bigger ones. Is there any big disadvantage or loss of strength when using a shim from the next size down? The Thudbuster doesn't come in 29.8 though I could order a Kalloy for the front post.