I just bought some Nashbar brand SPD MTB pedals to replace an old pair I had on my MTB. I attached the cleats to my Specialized shoes and found that I could not clip in. I had a friend inspect what was happening when I was trying to clip in and it appears that the sole or tread on the MTB shoes is interferring with my ability to clip in. The cleat is too recessed. I have been looking around online for shims that will push the cleat further out and haven't been able to find anything. The Specialized shoes are older and didn't come with any adapters or shims (got them off of ebay). I am not sure what to do at this point. Do they make shims for SPD cleats? Should I just get different shoes?