Vector 2S vs CycleOps Hammer. For example, a 10min warmup at relatively constant effort was 265W vs 229W. I understand that the pedals see maximum power, but is 15% loss really acceptable and anticipated? It seems ridiculously high to me. Here is their response. Note that both instruments were calibrated immediately prior to this ride.
Hello!
Thanks for the note. So, discrepancies like that are completely normal, and frankly to be expected. There are many variables which come into play in situations like this. The thing to keep in mind is that both power meters are accurate for where they’re measuring the power.
Generally speaking (sometimes this is not the case, depending on a handful of things) something like a pedal power meter will read a touch higher than a trainer. This is because the data is coming essentially straight off of your body. By the time the trainer “feels” and measures your power output, force has been traveling through the entire drivetrain of the bicycle, and depending on a handful of things (stuff you wouldn’t necessarily even thing about, like frame material, structural integrity of said frame, chain stay flex, chain integrity, etc) there will likely be a discrepancy between that and a meter measuring force direct from your legs. A comparison would be horsepower readings on a car - crank (engine horsepower) will always be higher than horsepower measured at the wheels as a result of drivetrain loss.
Hopefully this makes sense, just let me know if you have any questions, and have a great day!
Sam K
Customer Support Specialist
15% is definitely more than expected, but from my experience it’s most likely the vectors are off and the hammer spot on. I have a hammer and it’s been nothing but totally accurate. Lots of friends with vectors have had issues
15% is definitely more than expected, **but from my experience it’s most likely the vectors are off **and the hammer spot on. I have a hammer and it’s been nothing but totally accurate. Lots of friends with vectors have had issues
Vectors are well-known for registering low when they’re not torqued properly, but I haven’t heard of them registering high.
both PM’s are probably around 2% … so if one is high and one is low… that’s possible 10w right there… then another 10-15w just for pedal vs flywheel… the the vector being 2(s) single sided, not to mention I found the vector2 being effected by the install torque level.
Vector 2S vs CycleOps Hammer. For example, a 10min warmup at relatively constant effort was 265W vs 229W. I understand that the pedals see maximum power, but is 15% loss really acceptable and anticipated? It seems ridiculously high to me. Here is their response. Note that both instruments were calibrated immediately prior to this ride.
Hello!
Thanks for the note. So, discrepancies like that are completely normal, and frankly to be expected. There are many variables which come into play in situations like this. The thing to keep in mind is that both power meters are accurate for where they’re measuring the power.
Generally speaking (sometimes this is not the case, depending on a handful of things) something like a pedal power meter will read a touch higher than a trainer. This is because the data is coming essentially straight off of your body. By the time the trainer “feels” and measures your power output, force has been traveling through the entire drivetrain of the bicycle, and depending on a handful of things (stuff you wouldn’t necessarily even thing about, like frame material, structural integrity of said frame, chain stay flex, chain integrity, etc) there will likely be a discrepancy between that and a meter measuring force direct from your legs. A comparison would be horsepower readings on a car - crank (engine horsepower) will always be higher than horsepower measured at the wheels as a result of drivetrain loss.
Hopefully this makes sense, just let me know if you have any questions, and have a great day!
Sam K
Customer Support Specialist
As rchung mentioned, using a single-sided power meter to challenge the accuracy of the cyclops trainer is not a strong argument.
Vector 2S vs CycleOps Hammer. For example, a 10min warmup at relatively constant effort was 265W vs 229W. I understand that the pedals see maximum power, but is 15% loss really acceptable and anticipated? It seems ridiculously high to me. Here is their response. Note that both instruments were calibrated immediately prior to this ride.
lube your chain. It isn’t likely to make much of a difference. So just do it cuz you know you should anyway.remove the pedals, grease up the threads, put them back on and ensure the garmin pedal is properly torqued. That is huge.warm up 10 minutes before calibrating the trainer. Get a few 5-10 second sprints in to seat the pedals. More pedals have temperature compensation than trainers, but may as well calibrate them both after the warmup and sprints.
Now, set the the trainer to a certain slope and hold a steady cadence. What is the offset?
Tom A says to try a one legged test…haha, if you can hold a smooth cadence, go for it. What’s that offset?
Vector 2S vs CycleOps Hammer. For example, a 10min warmup at relatively constant effort was 265W vs 229W. I understand that the pedals see maximum power, but is 15% loss really acceptable and anticipated? It seems ridiculously high to me. Here is their response. Note that both instruments were calibrated immediately prior to this ride.
lube your chain. It isn’t likely to make much of a difference. So just do it cuz you know you should anyway.remove the pedals, grease up the threads, put them back on and ensure the garmin pedal is properly torqued. That is huge.warm up 10 minutes before calibrating the trainer. Get a few 5-10 second sprints in to seat the pedals. More pedals have temperature compensation than trainers, but may as well calibrate them both after the warmup and sprints.
Now, set the the trainer to a certain slope and hold a steady cadence. What is the offset?
Tom A says to try a one legged test…haha, if you can hold a smooth cadence, go for it. What’s that offset?
I recoat the chain in hot wax every 500 Zwift miles. It’s actually in process as we speak.
I’ll do this all again, but I’ve never seen anyone claim that improper torquing or pedal seating results in HIGHER wattage, only lower. Right? The pedals are reading higher than the trainer.
I always calibrate after the 10min warmup.
So have the trainer hold a particular resistance and then read the difference between the two meters?
Basically, it’s all over the map unless you get it right at 15 ft lbs. Correct torque looks like +/- 15W.
To compare a powermeter vs. the trainer, I’d rather put the trainer at a constant resistance (or slope %) and just spin at a steady cadence. That takes any trainer thought and compensation out of the equation.
Also, note that hot wax takes a little while to break in. I forget what ceramic speed says, but maybe the 10 minute warmup is insufficient…not sure.
For what it’s worth I had a 25 watt discrepency between my p1 pedals and my power beam. Got trainer road and cycleops involved. Both said make sure firmware is up to date which I did. Still was off. Cycleops suggested I calibrate the power meter to the trainer using the freeride option in rouvy. Did the spin down calibration with both pedals and the trainer paired. After I did this the trainer and my measured power output were within a couple watts at all times. After a few rides this calibration starts to slip so I perform again and back to within a few watts. Hope this helps.
Both trainerroad and cyclops have followed up with me to make sure everything is working properly.
Basically, it’s all over the map unless you get it right at 15 ft lbs. Correct torque looks like +/- 15W.
To compare a powermeter vs. the trainer, I’d rather put the trainer at a constant resistance (or slope %) and just spin at a steady cadence. That takes any trainer thought and compensation out of the equation.
Also, note that hot wax takes a little while to break in. I forget what ceramic speed says, but maybe the 10 minute warmup is insufficient…not sure.
Garmin recommended the advanced torque test, so I’ll see what that has to say also. Dude, I’m gonna be so disappointed when my FTP is actually 3.3 w/kg, not 3.8.
Slowman’s response is more convincing than mine, but I have a Stages PM with a hammer and have seen differences of maximum 15W all at lower intensity. As output increased the difference was lower.
