Deciding which PM device is right for me...
Ok, power gurus, after receiving much helpful feedback to yesterday's question, I am now in serious power meter research mode. My thinking is currently as follows:
I have to first make the global decision between a wheel hub-based vs crank-based system, because iBike doesn't seem to cut it, and the pedal-based systems aren't quite ready yet. I'm strongly leaning to crank-based system, b/c while I like the idea of the portability of a wheel (then again, I only own one bike and am not sure I'll ever get a second one), I don't like the idea to having to resort to a disk to get a rear race wheel. Yes, I'm pretty sure that one day I'll want to have race wheels.
Looking at crank-based systems, the two big guys are SRM and Quarq. Price point on Quarq seems to be lower, and I can change the battery myself as opposed to with an SRM. So, looking at the Quarqs (and having spoken to their customer service today), it seems I have three options that are compatible with my bike (btw, I ride a Cannondale Super Six w/ BB30 and Gossamer FSA cranks):
* 2012 Quarq Cannondale power meter with Hollowgram SL crankset
* SRAM S975
* SRAM Red 2012.
The SRAM S975 does not have power balance, which displays ratio of power generated in left vs right drive stroke. That's a big deal for me since I suspect I'm much weaker on the left and would like to balance that. Leaves the Quarq Cannondale poewr meter vs SRAM Red. I'm told when using the latter, it is recommended using the enter Red group for compatability purposes (I have Shimano 105), whereas the Cannondale power meter has no such compatibility issues. So while the SRAM Red is about $800 cheaper, I'd have to factor in the cost of upgrading my group. Also, the Cannondale power meter is lighter. So, based on all that, I'd be leaning to the Cannondale power meter.
How does this logic sound? Am I missing something? Is there something else I need to consider? (Haven't thought much about head units or data analysis s/w yet, that'll come later...). Does anyone have the Quarq Cannondale power meter and can provide feedback?
Thanks again for your time and feedback!
Comments
I have an S975 SRM, but that's only because I got it during one of the Tour du France deals and it actually cost less than a Quarq. I can't speak to the difference between the Cannondale and the SRAM Red, but if you're being a weight weenie, the Cannondale is ~100g lighter than the SRAM Red. BUT if it costs $800 more, you can replace your 105 Shifters/FD/RD with 2012 SRAM Red stuff for a little less than the $800 difference in the Quarqs. Those SRAM Red components will save you almost 300g over your 105 stuff AND you will have better sweeter components. So for roughly the same cost, you can have much better components AND save almost 200g of weight.
Any way you decide to go, you should hit coach Rich up to buy it through his wheel builder hookup to save some dough.
I love my Garmin Edge 500 head unit when you cross that bridge and it's only ~$200 new on eBay.
Kate:
In terms of a head unit, I use a Joule 2.0 but what ever you choose, I strongly suggest your get one that displays normalised power, IF, TSS, power etc in real time.
That said, if you already have a Garmin xt310 for running with pace, you can use that as your power head unit.
If you don't have a GPS pace watch for running (like the xt310), you might consider the Garmin 910 that would give you all the power metrics I mentioned, plus running with pace, as well as being able to use in the pool and open water swimming.
As far as compatibility with cranks and components, I can't speak about needing to put the SRAM Red with Red components vs. 105. My SRM is a DA7800 and I have swapped it on bikes that are running Campagnolo without any problems, so I can't see that the SRAM wouldn't work with 105, but maybe I'm missing something. Don't know enough about it to speak as an expert
The Quarq is definitely less expensive, and I'm told that it works very well. The battery changing thing with SRM isn't a major issue to me. I send the unit back to SRM every couple of years to get it replaced and re-calibrated; usually takes less than 2 weeks total turnaround time. As far as left vs. right power, I don't know that any unit does that; the strain gauges of all the crank-based units are built into the unit on the spider arm, so there's no way to truly measure independent power.
Agree with what the others said about using a PT. Easy to use a training wheel with a wheelcover= low-cost racing wheel that is a disc. (well, low cost meaning you don't have to buy a race wheel in addition to the training wheel). And the wheelcovers are really nice. I got one for my son's racing wheel and it works really well (and even looks good, too!)
http://forum.slowtwitch.com/forum/Slowtwitch_Forums_C1/Triathlon_Forum_F1/Which_powermeter_P4233706/
Yeah, I've been watching that one pretty closely. I've also seen some anecdotal evidence across the internet of folks NOT marrying the RED power meter to Red components, but I'm not sure I'd be willing to risk that - I'd assume if there were performance issues w/ the power meter, any warranty/guarantees would not apply since Quarq specifically states it'd only work with Red components. Plus, my 105s are still fairly new and while I'll eventually want to replace them, there's really no urgency to right now. For people who don't care about the Powerbalance capability, the s975 sounds like a good fit, but I think I'd get a lot of the powerbalance given my uneven pedal stroke (at least I think it is!).
I've not heard much good right now on the right vs left power readings. I would wait a few more years and let them improve on what they have.
Either way, the sensor is not really that sexy and they sort of disappoint. I mean, they don't have any buttons or lights or do anything you see with your eyes or feel with your hands. They don't little noises or anything. These units are all high quality and measure power consistently within what I consider the same range. The real interface that actually you work with is the head unit. That is the part that you stare at for the entire ride. It has the actual functions that you will use. Think about a great head unit. The 305 is a little limited.
I have started to think of it this way. The head unit is the user interface and the power meter is the like the mother board on your computer. When it is working right, you shouldn't know it is there. That's how I feel about my crank based meters.
Regarding left/Right power. Based on my reading of the literature, it seems the jury is out regarding the usefulness. I don't know what you would do with the data. I have not seen any coaches, our included, come out with guidance regarding the importance of it. It seems like a technology that solves a problem that may not exist.
Again, all of this is my n=1 and my humble opinion as a power meter collector of sorts...
As for head unit, I run an Edge 500 and I suspect if you polled all of EN you'd have a majority using the Garmin. Some long-time Joule users, including Coach Rich, have switched over to the Garmin in the past year or so...you'll find threads about the comparison of the two in lots of places.
FWIW - I've used the Edge 500 for a few years and it's great - does everything I need.
I use a Garmin 800 to collect the data. I also use an $80 disk cover and have ridden a 5:01 IM bike split on them. No need for really expensive race wheels, IMO.
Thank you everybody for your thoughtful feedback and responses. You really did help take the fear of technology out of the equation for me.
@ Dino - the 'motherboard' analogy seems spot-on!
I hemmed and hawed quite a bit b/c you all made some very good points in support of various options, but in the end, I went w/ the Cannondale hollowgaram and will keep the 105s for now- thanks to Coach R for hitting up his dude to help me out a bit. Will also get the GArmin 500 head unit. I have some other Garmin devices, so hopefully the learning curve on how to use it is not so steep.
And I promise holding off on posting any questions on what the @#$#@$ all those numbers mean and how to analyze them for at least one week after I start using my PM! After that, all bets are off...