I bought a pogo stick seat post (has the shock absorber right under the seat mount) for my bike, but had to buy a shim cause the diameter of the new post is smaller than the old. I also bought a seat post mounted rack. The problem is, I canít tighten the rack enough unless I mount it on the shim. Now with the rack mounted, it leaves just a few inches of shim left for engagement. My question is, will this be ok or should I buy another shim so the full depth of the shim is inside the bike tube/clamp?