**Nobody else would suggest this, so here goes. **Have you looked at the Kurt Kinetic Power Computer? If you already have a good fluid trainer, you can do repeatable, “power-based” training on that. In fact, you can use their formula for calculating the power curve on your own if you want. Not accurate, but repeatable results…
Now if you don’t already have either a Cycleops or KK fluid trainer, you might as well eBay an old powertap.
http://www.kurtkinetic.com/calibration_chart.php
http://forum.slowtwitch.com/...a%20kinetic;#1433050
Actually, that was a suggestion in the very first reply…
The KK fluid trainer is reasonably accurate for STEADY STATE power. I.e., it’s acceptable for 30min efforts. But, it’s based entirely on the speed of the trainer. So it’s not really any different than just keeping track of your speed and trying to hold that constant on the trainer. You can do that with any computer that picks up speed off the rear wheel. It’s also VERY bad for short intervals - which is what I think most of use trainers for - get on, ride hard, get off, hopefully before your crotch is entirely numb. Since the KK thing works off speed, if you do hard sprints, it will totally miss the power spike at the beginning. Sure, once you get the wheel up to speed it’s accurate, but again, you are still no better off than if you just monitored your speed on the trainer week to week.
In terms of SRM being the best, I think this was the case, but in my own experience and in many others, it appears both Quarq and PT are more consistent and reliable than SRMs are now, especially with big temperature drifts. SRM is certainly no more accurate than either a PT or a Quarq.
The cost argument in terms of “worrying about wheels” is also ONLY relevant if you already have a wheelset.
PT Elite+ Mavic Open Pro with computer is $1099 MSRP. Now you could easily put a disc cover on that wheel and have yourself a very fast race wheel. But let’s say you want a race wheel. You want a “regular” disc. You can get a Zipp Clincher PT disc for $3465. Both wheels at TriSports.com. And then let’s say you want a SRAM RED 10spd crank, that adds $319 @ performance.
With an SRM, going with the cheapest option - which is heavy and not really a very good crankset - you’re at $2,995. For a nice carbon crank, you’re closer to $3,695. Add in $100 for a decent open pro training wheel on reasonable hub (say ultegra). And then you want a disc - $1850 for the non-PT version of the clincher disc.
$3695 + 100 + 1850 = 5645 for an SRM set-up
$3465 + 1099 + 319 = 4883 for a PT set-up.
Now, of course, you can get both set-ups cheaper if you go with an 808 with PT and get a cheaper crankset OR if you get a cheaper rear race wheel and downspec the quality of the cranks with an SRM. You can also get a cheaper disc if you get the HED wheels, which use a standard PT SL+ hub (as opposed to the Zipp’s which use a Zipp hub with PT electronics), or cheaper wheels if you choose HED hoops as well.
Even if you choose to add a non-disc rear race wheel, say for Kona, your incremental cost is still less than you might think, since you can order the wheel built without a computer, which drops the cost a couple hundred dollars. In that case you’re close in cost if you wanted a top-quality crankset, and you’re not too much more expensive if you wanted an el cheapo crankset (and if you are going to quibble about crank quality when you’re spending close to 10,000 total on wheels and cranks and such, then whatever).
Yes, with an SRM you have the opportunity to buy used race wheels. But, you also have the opportunity with a PT to pick up multiple used hubs, which can drop your cost just as much.
If you already have a significant investment in race wheels, then yes, a crank-based system is the way to go. But if you don’t, it’s basically a wash. And if you want to talk about crank-based systems, Quarq should definitely be included.