Does anyone here use the ultra 11 speed cassette with Shimano Rs81-C24 wheels? My question is this: I currently have Shimano Rs81-C24 with 8 speed sora components (with a spacer). I didn't think that the hub would have enough room to fit a cassette with more sprockets since the 8 speed already occupies most of the space there. Can anyone help? Will have problems upgrading from 8 speed to 11 speed on Shimano Rs81-C24?