My Madone came with a Tiagra 12-30 cassette (105 shifters/der.), which isn't ideal for the flat crits I've been racing the last few weeks. I picked up a SRAM 12-25 cassette off of Ebay (probably Apex, not totally sure because the guy didn't label it but it was only $15). I put it on my race wheel and put the 12-30 on my spare wheel that I use for the trainer. It seems that when swapping between the wheels, there's a huge amount of adjustment required in terms of cable tension. It's such a huge difference that I had to count the SRAM cassette to make sure it's 10 speeds! I know that the spacing between the cogs themselves is the same between the brands, but is it possible that I'm missing a spacer beneath the SRAM cassette that is required when using it with Shimano shifters, or maybe the different wheels have different adjustment requirements? The "race" wheel is a Vuelta Corsa Superlite, the backup is the Bontrager rim that came with the bike. I'm new to brand mixing, so I just want to be sure I'm not missing something basic.