For a long time I've been a champion of the Kurt Kinetic Road Machine ergo.  I think I own 6 of them?  It's got a stonkingly heavy flywheel which makes it good (ok, at least, viable) for standing start and acceleration work, which sprinters need.  It's not without issues - the main one being tyre slip under heavy torque - ie: Those standing starts that we want to train on it.  It's issue is that it uses a roller drive, and we can work around that with skateboard deck tape (lasts around 5-10 starts depending on the rider) and it does eat tyres.  We can mate it up to a road powertap and get power and torque (sorta) from it, which is good too.  They're also pretty quiet (fluid), unlike wind trainers.

But ... it's roller driven.  A direct drive would be better, without doubt.  Of course, to do this, would mean that the powertap wouldn't be any use, so we'd lose our data.  Bugger ... We could use SRM's, if we had a huge budget, alas, not this week!

The other good trainer is the BT Ergo, which is a direct drive wind trainer.  It's bulky, it's very expensive and it has next to no inertial load (no flywheel) so it's not good for training acceleration (great for constant power etc, but not for sprint work where we want to target acceleration).   It, being direct drive, does not suffer from wheel slip though (although, since it has no significant flywheel, that's not really an issue with it anyway!). There's a power-based trainer or two around as well, the Computrainer is probably the most famous of them, but it's not a sprinters trainer.  And the AIS's Wombat, the VIS's Godzilla etc (custom made jobbies, with uber-flywheels and SRM's and a big budget to put them together!)

Here's a new player on the block (thanks to Scott McGrory, we had a brief chat about it yesterday at DISC). It's the Lemond Revolution.  Direct drive (no slip) and a flywheel.  We lose out on power measurements with it, at least at the moment, but it might be worth a play - I will see if I can get one to add to the collection of trainers I have, to see if it can fill a niche in our sprint ergo program.  If the flywheel has enough mass and we gear it up right it might be a valuable tool.