The vectors are not necessarily easier to transfer than crank based. If your TT and road bike can use the same crank, it might be easier to swap cranks.

The vectors seem to be pretty good accuracy wise if you take the proper care to install them properly. There is probably no benefit to the left/right power unless you are planning on doing some deep science with it. Really deep.

SRM/Quarq/Power2Max all have pretty good reputation these days, in about that order. Price is also in that order =)

Powertaps are great, downside is if you have just one, you have to use the same wheel for training and racing. This can work out really well with a disc cover.

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Kat Hunter reports on the San Dimas Stage Race from inside the GC winning team
Aeroweenie.com -Compendium of Aero Data and Knowledge
Freelance sports & outdoors writer Kathryn Hunter

What bb do you have on your road and tri bike currently?

My personal preference is crank based (quarq or srm). Hub's are great too but not if you use multiple wheel sets (I have a trainer wheel, training wheel, 808 rear, and a disc). If your bb's are the same, its really easy to swap cranks between the two. Once you do it once, you will be amazed just how easy it is.

I'm not sold on the vectors yet. Seems to be many users have had issues when they are constantly swapping back and forth (but I honestly believe it be user error for the most part). It's just something I didn't want to deal with.

Some people rave about the stages but I'm not keen on it. It only measures left side power but if you are "ok" with that, then it is a great cheaper option.

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I use a Rotor 3d Power2Max. Been fantastic and only takes two minutes to swap from one bike to another.

Thanks for the info Jack- Sounds like I need to learn how to switch cranks out. Crank based is what I really want. My tri bike has FSA cranks and my road has Rotor Cranks that are paired with DI2. Do you think the DI2 part matters?

Not sure about the BB....my guess is the BB-30 does that sound right? Same issue with the wheels too, that is why I lean away from hub based power.

A lot of cranks are easier and faster to transfer than the Vectors. Takes all of 5 minutes to do both bikes. However, it does mean that your road and TT bike need compatible BBs. If you want to add a 54 or 56 ring when TT-ing you will need to recalibrate (and I don't mean garmin's definition of recalibrate)

The Vectors require a special torque wrench crowfoot, requires you to hold the pods stable while your tightening them (so three hands?) It needs to be done carefully or you damage the pods. This takes longer, but it shouldn't take hours. You should be able to add a 54 or 56 ring without any issues. If you swap crank lengths between bikes, remember to update your gps.

If you already have a computrainer (power indoors) and you use a disc cover instead of a solid disc, hub based power should be very easy. Hub power requires multiple power meters if you have an indoor wheel, a disc wheel, a training wheel, and a deep section road race wheel.

I don't know if the Vectors drift after swapping between bikes. If they do, you'll have to swap a week before your race to let them settle. Quarqs drift when you swap rings or crank arms, but not really when you swap it between bikes.

Thanks Grill- I am going to look into this.....never knew you could just swap out cranks....if it is easy that is the way to go for sure!!! Seems like all the power meter market leaders are using crank based power.

No.

It is as long as you have compatible bottom brackets. My bikes are BSA and PF86 so the 24mm Rotor 3D is perfect. If your bikes are BB30 then the Rotor 3D+ is a better option. If you already have a Rotor 3D+ chainset, then you can just buy the Power2Max spider and save some money. Also, P2M doesn't require any calibration if/when you change rings or bikes.

Quote:

If you swap crank lengths between bikes, remember to update your gps.

I don't understand this one, what's to update?

Be sure about the BB. Rotor and FSA will both fit on BSA, BB30, BB386, BBRight, etc. but you can't necessarily swap if one BB is BB30, and the other is BB86. So make sure. Then double-check before you pay $1,000 for a device that doesn't fit both bikes.

Easiest: both old-fashioned threaded BSA68 (68, not 86)

Difficult: one BB86 and the other PF30. Then you've got to play with spacers, etc.

Worst case: BB92 or BB386 which might not fit any crank based power meter.

a) a crank length setting, otherwise your power reading is wrong.
b) update the device's firmware, so you can set (a)

I second Grill's comments.

A Power2Max S power meter would be an easy solution if you have BB30 on both bikes. I like the P2M solution because you can fit just the spider to the Rotor 3D cranks, which is especially useful if you run a shorter crank on your TT bike than on your road bike, for instance.

I'm looking at buying P2M S model this autumn. My only reservation would be the move to Bluetooth, which I feel is imminent for PMs, but with only Stages or PowerTap offering a Bluetooth powermeter, this may well be another year or so down the line.

False.
Edit: ok maybe not false for the vector

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Kat Hunter reports on the San Dimas Stage Race from inside the GC winning team
Aeroweenie.com -Compendium of Aero Data and Knowledge
Freelance sports & outdoors writer Kathryn Hunter

ha, spot the guy who doesn't have a power meter. (ie me)
I presume this is only applicable to pedal based PM?

I have a HED rear wheel with a powertap. Its my training/race wheel. I just put on a wheel cover for racing. I have no complaints, putting on the cover is easy and it's easily transferable between bikes. Only downside is if I do a race that doesn't allow discs I'm screwed. I'd have to rent a wheel with a powertap, lucky 99% of races allow discs. In the immediate future I plan on buying a crank based system and getting a dedicated race wheel. You should look into Power2max. Excellent reviews and the Classic model is on sale.

No, it's not specific to pedal based power meters. It's also not something you normally change daily.

Power meters measure torque and speed, and calculate power. Any lever (eg. crank or wheel) will multiply torque, and hence you'll get a wrong power reading if your lever length setting is wrong.

I have no personal experience with the Vectors for crank length. Some people say setting the crank length is necessary, some say it's not. Djconnel had some stats on his blog about his Vectors reading wrong when they thought his crank arm was 144.5 mm in length (hint: his crank was longer)

My Quarq needs a crank length setting when calibrating (not zeroing) it. I can't remember ever setting it on my Ergomo, but I never changed the crank length.

I assume a Powertap needs to have a fairly accurate wheel size setting, but it might be able to calculate that accurately from speed, since hub rotation has a constant relationship with speed.

Also, if you are swapping cranks, you do not need to take off the pedals. So by swapping cranks, your can move the vectors just as quickly as you can move a quarq/srm/power2max to another bike.

The advantage the the vectors still retain is if in the future you want to crank with different crank length or switch to compact crank, the vectors are much easier to move to the new crank than the others. But, yes the vectors are much slower to install on a crank than were hoped for when they were announced. They also lock you into a pedal system.

Love my rear PowerTap wheel and disc cover. No complaints whatsoever. CycleOps has great customer support too. Wheelbuilder has some great PT sales from time to time.

How do you define "market leaders"?

By share of market?
By profit?

So I have the reynolds assault wheels with the g3 power tap. Is there a disk cover that I can use for that wheel?

If you can wait until September for more info, Brim Brothers is finally releasing their shoe/cleat-based system -i.e. multi-bikes, just have speedplays on each and you're good to go. If you are not the compulsive type, wait til next spring to survey the other emerging market entries.

edit, sorry, was replying to the question about the wheel cover - this is where you get them, and there are instructions for figuring out compatibility.

http://www.wheelbuilder.com/aerodisc.html

powertap is definitely one of the leaders, and are hub based.

In fact the powertap has some unique advantages over crank based

1. it is superior for field testing purposes
2. you don't need a magnet, and those can be a pain in the ass
3. you get speed data for free, which is nice

On the other hand chain lubrication affects the power reading, so you need to not let that get out of hand or it will pollute your data, and you don't get accurate cadence data 'for free', you would need to add a separate cadence sensor for good cadence data.

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Kat Hunter reports on the San Dimas Stage Race from inside the GC winning team
Aeroweenie.com -Compendium of Aero Data and Knowledge
Freelance sports & outdoors writer Kathryn Hunter