POWER METERS: Crank, Hub or Pedal-based?

['Dale]

Activeworx bring them in and support them:

http://www.activewor...name=SRM%20Road

 

The new wireless versions are ANT+ compatible and will work with the Edge 800.

 

I like Quarg and would not want to replace my Hollowgram crank with a SRAM crank to fit it.

SRM seems to slot right in with my existing crank, as I understand it.

 

Is my understanding correct?

Edited March 26, 2012 by danseuse

[andrewbell]

Where's the best prices for a Sram Quarg?

 

I am looking for 2012 Red crankset.

 

the official agent for this is Bruce Diesel, i have contact details if you require.

['Dale]

the official agent for this is Bruce Diesel, i have contact details if you require.

 

Thanx, andrewbell...

 

I am still reviewing all options.

Will keep your offer in mind.

[Minion]

All current crank-based PMs consist of a custom spider (the part that holds the chainrings) that contains all the electronics that is then bolted on to the crank arms from a normal crank. This is why you cannot get a PM for all crank types - it needs a removable spider or the crank manufacturer needs to make a special arm just for the PM (e.g. Campag Super Record SRM or SRAM Red Quarq).

 

You can get a Cannondale Quarq spider, but you have to get it direct from Quarq: it doesn't come through the SRAM supply chain.

http://www.quarq.com/cinqo_cannondale

[Minion]

http://2.bp.blogspot.com/_urSQl6wUA5g/R4AZeNOHn-I/AAAAAAAAA4s/2MDhDauY660/s400/CinQo_Spider.jpg

 

This is really the only part that is actually made by Quarq (or SRM etc.). The crank and chainrings come from other manufacturers. The individual spiders are then machined to match these - hence Cannondale, Specialized, SRAM etc. spiders.

[andrewbell]

I bought the quarq spider and had it fitted to my hollowgram crankset. cost was about 14k. and i kept my joule 2.0 head unit.

Edited March 26, 2012 by andrewbell

['Dale]

All current crank-based PMs consist of a custom spider (the part that holds the chainrings) that contains all the electronics that is then bolted on to the crank arms from a normal crank. This is why you cannot get a PM for all crank types - it needs a removable spider or the crank manufacturer needs to make a special arm just for the PM (e.g. Campag Super Record SRM or SRAM Red Quarq).

 

You can get a Cannondale Quarq spider, but you have to get it direct from Quarq: it doesn't come through the SRAM supply chain.

http://www.quarq.com/cinqo_cannondale

 

:thumbup:

['Dale]

I bought the quarq spider and had it fitted to my hollowgram crankset. cost was about 14k. and i kept my joule 2.0 head unit.

 

Brilliant!

 

I have the ANT+ head unit.

Have the right crank.

Now just 14K for the spider...

['Dale]

Brilliant!

 

I have the ANT+ head unit.

Have the right crank.

Now just 14K for the spider...

 

:blush:

[Spinnekop]

Just remember to decide on a chainring set first. You'll have to let Quarq know what you are going to use in order for them to preset the offsett of the quarq, i.e callibrate it.

[Minion]

Just remember to decide on a chainring set first. You'll have to let Quarq know what you are going to use in order for them to preset the offsett of the quarq, i.e callibrate it.

If you don't want to decide just yet, you can also set the slope yourself at a later stage with an iPhone/Pod/Pad and the Qalvin app and the ANT+ dongle.

[LOOK695]

If you don't want to decide just yet, you can also set the slope yourself at a later stage with an iPhone/Pod/Pad and the Qalvin app and the ANT+ dongle.

Is it compatible with Campag cranks

[Spinnekop]

Is it compatible with Campag cranks

 

Campy cranks do not come out with a removable spider although they are in process to develop a SRM for campy crank arms.

By 'Campy cranks' you mean chainrings? You get 11sp chainrings that fits 130bcd spider for the Quarq.

[The_Break]

Crank - more accurate measurement.

 

It's like when you do torque measurements on a motorcycle - you will get a higher reading at the drive shaft that what you would get on the wheel.

 

Edit: typo

 

Not obviously the crank. Where you measure the power and the loss through the drivetrain has nothing to do with actual accuracy for your training itself. Both SRM and Powertap are very accurate in terms of consistency and that is what you are looking for. The only thing you will need to consider is what system you did do your baseline testing on in order to determine your power training zones. Try do your baseline testing either on youur unit on a trainer or in a lab with similar setup and powertrain losses (although almost impossible to predict).

 

I am not sure how accurate pedal powermeteres are but if within 2% or so I would go for those as they are by far the easiest to change fromm bike to bike. SRMs are heavy and not as stiff as say a Zipp crank and Powermeters are not that great in terms of changing between race and training wheels. I would seriously look into pedal ones next time I buy. CUrrently have Powertap. Couldnt afford the SRM as it is very expensive in comparison.

[LOOK695]

Campy cranks do not come out with a removable spider although they are in process to develop a SRM for campy crank arms.

By 'Campy cranks' you mean chainrings? You get 11sp chainrings that fits 130bcd spider for the Quarq.

Thanks. What I had meant is whether the power meter is compatible with campag. I thought that the bcd for campag chainrings is 135mm? I am asking because I am using campag and would like to get a power meter soon. My other option is to get a pedal based pm, especially in my case where I am using the LOOK Zed 2 crank

[Minion]

Campy cranks do not come out with a removable spider although they are in process to develop a SRM for campy crank arms.

It's now available for 'only' EUR 3800

 

Thanks. What I had meant is whether the power meter is compatible with campag. I thought that the bcd for campag chainrings is 135mm? I am asking because I am using campag and would like to get a power meter soon.

You won't be able to use Campag 135mm BCD chainrings, nor will you be able to use their 110mm BCD chainrings (one of the bolts is different to everyone else's compact rings).

 

You do, however, get after-market 11sp rings that will fit the Quarq and give acceptable accuracy. If you're on 10sp, the SRAM Quarq will work perfectly with a Campag drivetrain (and doesn't look too out of place) - this is what I'm doing. A lot of people also say they're running a 10sp SRAM Quarq on an 11sp group with no issues.