Power2max - which crank?
GGBiker
Posts: 450
Close to buying a power meter, deciding between powertap rear wheel and a power2max crank based system.
Thought the powertap was an obvious choice given that I want to change it between 2 bikes fairly regularly and this would be easiest way to achieve this. Only downside is the weight 1150g for the powertap pro rear wheel (which I believe has a DT swiss 465 rim and dt swiss competition spokes, 32 hole).
I want to use it for training, racing and short TTs (max 10miles).
The alternative suggested by a poster here previously was the power2max crank based system.
On
Obviously I would need to change this between bikes so my question is which of their cranks would make this easiest? I have campagnolo Centaur on both bikes so the crank needs to be compatible with this. One of the bikes has a FSA gossamer crankset so I could use the chainrings and non drive crank (it's supplied without these I think).
Is the fsa gossamer a doddle to switch between bikes or would one of their other options be easier (eg rotor 3d)?
Would want something very easy to switch so that I actually use it!
Thought the powertap was an obvious choice given that I want to change it between 2 bikes fairly regularly and this would be easiest way to achieve this. Only downside is the weight 1150g for the powertap pro rear wheel (which I believe has a DT swiss 465 rim and dt swiss competition spokes, 32 hole).
I want to use it for training, racing and short TTs (max 10miles).
The alternative suggested by a poster here previously was the power2max crank based system.
On
Obviously I would need to change this between bikes so my question is which of their cranks would make this easiest? I have campagnolo Centaur on both bikes so the crank needs to be compatible with this. One of the bikes has a FSA gossamer crankset so I could use the chainrings and non drive crank (it's supplied without these I think).
Is the fsa gossamer a doddle to switch between bikes or would one of their other options be easier (eg rotor 3d)?
Would want something very easy to switch so that I actually use it!
0
Posts
If you order with the cranks it will include both arms but no chainrings. My suggestion would be to buy with cranks and then convert the bottom brackets on the bikes it'll be used with so you can swap them. Rotor 3D uses a standard Shimano external BB so you can choose from a few manufacturers. If you have an FSA already this may be an option although it's Shimano standard BB as well, at least you have a compatible BB and would only need to buy one more for the second bike.
Bob Tobin at Cyclepowermeters sold me a 28H track PT already built onto a DT565? Rim. I would have preferred the hub on its own & had it built into a wheel by Derek @ Wheelsmith, but it was his last one @ £600, it was too good an offer to pass up. Derek told me It is not the best rim, heavy & not that stiff, & I'll change it sometime, but it works just now.
Personally I would put in an order for the Rotor power cranks. It wil work out a little motte expensive but while you are waiting (on back order) you can save the difference.
Might be worth discussing your needs with Bob at Cyclepowermeters. Very helpful.
Thanks for everyone's input.
I'm sure you'll be happy with the PowerTap until the torque tube fails and Paligap want £425 to fix it.
FWIW I've had a P2M since Sept 2012 and after a couple if initial software bugs (that P2M fixed straight away) it's been superb. Mine is the SRAM S900 version and I swap it around on an almost weekly basis. It takes a couple of minutes and I really can't see how this would cause issues with the bottom bracket (and even if it did mean replacing the bb more often, they only cost about £20).
So if you can live with one wheel for all your riding then I'm sure you'll be happy with the PowerTap, but I've owned both a PowerTap and P2M and I'd much rather have a P2M.
Errr...well it wasn't sorted on mine which was the latest version with the software update. And if you look into the first edition, it seems not everyone had drift issues then too. Clearly I'm not speaking for all users but just sharing my experience. I also gave the product a good 2-3 months of heavy use...it wasn't an assumption from a couple of rides. I hope it is now sorted as the more PM suppliers the better.
'a little more finicky' were the words I used. No mention of an issue with extracting the crank. 3D+ = 2 mins v 3D = 1min
the SRM is crazy expensive!
Sounds like you're just unlucky. There isn't a single PM on the market (SRM included) that always works for everyone.
How have you established that there's significant drift that leads to a noticeable error in the power readings? The ZO will always change with temperature, but if yours is working properly the ZO will be modified by the auto-zero algorithm as temperature changes. Unfortunately you can only check the ZO by doing a manual zero so you don't really know what the auto-zero is doing. This is obviously not unique to the P2M, but the same for any power meter with an auto zero function (e.g. PowerTap). It would be great if the P2M and other power meters would start sending the ZO value via ANT+ as an extra data field so you could check the value on your head unit. As it is you have little idea of how well the auto-zero works unless there are huge temperature changes that lead to errors in the power readings of tens of Watts.
If you're convinced there's an issue with your P2M then I'd send it back to Germany for investigation.
How many points was the ZO value changing by each time you recalibrated? Mine sits at around -880 in the house and drops to a low of around -865 when it's sub-zero outside. It always settles after about 15-20min after going from cold-hot or hot-cold. I was obsessive about doing manual ZO when I first got it and I'd stop several times, but after finding it always settled after about 15mins, I generally only do a manual ZO at the start of a ride and occasionally 20min or so in.
Running Campag 11 and Rotor 3D+ with normal round chainrings. Shifting is excellent. Removing the Rotor 3D+ involves removing the crank bolt and then reversing the outer bolt which acts a self extracting tool to remove the non-drive side crank. Pretty easy once you get the hang of it. Any crank based system is a bit of a faff to swap but I guess if it's a couple of times a year then it's not too bad.
i have a problem where my shimano bikes - road is running a fulcrum chainset (same as campag ultratorque 25mm) and my TT is FSA running 24mm.
ideally i`d like to keep the fulcrum chainset and put the same BB on the TT, but P2M dont do a campag setup.
cheers
ben
The reason Power2Max don't do a Campagnolo chainset is that Campag's don't have removable spiders like the Rotor. The Power2max replaces the Rotor spider.
Cheers
didnt know you could run bb30 on bsa68
maybe i need 2 new chainsets...