Stopping the slip
Doing big gear starts on a Kurt Kinetic Pro with the big flywheel
We do a lot of high strength work on Kurt Kinetic Road Machine trainers. I'm a big fan of these, they work, they're (compared to the BT and Wombat etc) affordable while not being cheap and nasty and there's an option to have a very heavy flywheel. We use the big flywheel for strength work. It fits on the "pro" version of the KKRM. With the Uberflywheel, the total flywheel weight is 18.25 pounds, or a bit over 8 kg. This takes some effort to get going. The Computrainer that all the enduros rave about would blow to bits with the sprint stuff we do, it's limited to about 1500 watts of electro-magnetic braking and I doubt it can cope with high torque applications. The only other thing that comes close is the WattBike, but that's not a cheap bit of kit and it's got its own flaws, most glaringly the wrong Q factor for starters, and yes, that can be fixed, but a $3000+ bit of gear should be right from the start!
Like everything, the KKRM is not perfect. For strength work, we load up with a big gear, for example we sometimes use 53x12 (119") for some efforts. This isn't really what the KKRM is designed for, but it is the best simulation of a standing start I've been able to find. With the superflywheel, it's harder than getting out of the starting gate. Ie: it's good specific strength training. BUT the rear wheel of a bicycle, no matter how tight we do up the tensioner, slips.
Until now ...
When I was over in Adelaide at the NTID sprint camp a couple of months ago, I had a look at what the AIS guys use, one of them has a KKRM, but he'd modified it, presumably for the same reason I have now modified mine. Skateboard deck tape around the roller. This might shred tyres, but it now means next to no wheel slip and a much better initial first three pedal strokes, as the roller starts turning rather than slipping ,which was the big advantage of the BT and the Wombat etc which are directly chain driven. I ducked up to Ringwood and bought a sheet of glorified sandpaper from Ballistyx (which is all deck tape is, it's a sticker combined with sandpaper), cut a bit to wrap once around the roller, stuck it on and trialed it last Tuesday at Spin. Wow. It works really well. We'll happy cope with more tyre wear for this improvement in resistance.
So now my kilo and 500m ITT riders (and team sprint starters, ie: me!) have a harder session when we do big gear standing starts on the ergos.