Owners of both powertap and SRM

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I already have some SRM`s on my TT bike and i`m about to purchase a powertap today.

Having read Hunter and Coggans book, it states that the powertap would show about 5-10 watts less than the srms as the power comes from the rear. I wanted to try and calibrate the srms with the powertap, so the question is whether this is about right?

I already have some SRM`s on my TT bike and i`m about to purchase a powertap today.

Having read Hunter and Coggans book, it states that the powertap would show about 5-10 watts less than the srms as the power comes from the rear. I wanted to try and calibrate the srms with the powertap, so the question is whether this is about right?Er, I'm pretty sure Hunter and Andy would have got it right..... but presumably there are individual differences depending on your drivetrain set up, how well it is maintained and even possibly the gearing you are using at any point (and hence speed you are travelling at) but they are probably beyond the limits of accuracy of these devices. I'm not sure if such losses are linear to speed or not.

OP: Put the PT on the SRM bike and test them. You'll either figure out how to tune the SRM to the PT or find a correction factor.

Keep in mind that the PT measures post-drivetrain and the SRM is at the crank, so there will be differences. I'll leave it to some other genius to figure the rest out...

I already have some SRM`s on my TT bike and i`m about to purchase a powertap today.

Having read Hunter and Coggans book, it states that the powertap would show about 5-10 watts less than the srms as the power comes from the rear. I wanted to try and calibrate the srms with the powertap, so the question is whether this is about right?
Check out the thread "SRM Zero Drift Offset"

Link is: http://www.cyclingforums.com/t365078.html

I already have some SRM`s on my TT bike and i`m about to purchase a powertap today.

Having read Hunter and Coggans book, it states that the powertap would show about 5-10 watts less than the srms as the power comes from the rear. I wanted to try and calibrate the srms with the powertap, so the question is whether this is about right?
Why don't you just calibrate both of them separately instead?