Slope of 6% on Drivo feels more like 8% or more

[webmaster]

I have set up a specific program on the Drivo using the desktop REAL application to simulate a climb of 6% over 15 km. When it enters the slope portion of the program, the effort required to do this feels more like 8 to 10%. How do I come to that conclusion, well the speed at which I am riding and the gear ratio. I am using a 36-25 and my speed is around 13.5 kph. However, in real riding when doing a 5 or 6% slope, I am doing between 18 to 20 kph. The watts vary on the road and I don't think the watts of my chain ring power meter are close to those of the Drivo so I cannot compare apples to oranges here.

I have done calibration of the Drivo but that does not make much of a difference. I have my weight set to 68kg. I have used to have a wired REAL Power and the speeds of the Drivo remind me of the 8 to 10% settings I used on that machine.

Can anyone shed some light on this? I would prefer to be setting up programs that are close to slopes I would like to train against rather than having to guess what I am doing.

[Elite Admin S]

Hi

Please can you tell me the serial number of your Drivo and the offset you get at the end of the calibration?

Regards

[webmaster]

Sorry for the delay in responding back with the information. I was trying out some ideas first to make sure I was comparing experiences correctly.

First off, part of the problem was that the wheel diameter was not correctly configured for my real world experiences. I needed to change the default of 2070 to 2096. That made a small change in the speeds but not enough to come close to what I experience on the road on 6% climbs. On my old Real Power trainer, my speeds were much higher and I would general do 8% climbs in a 23 rear cassette. Here I am doing "6%" in a 25 rear cassette.

The calibration value from the trainer through the Real desktop app is 6438 and the serial number is 42167.

I am going to do another test to see if my C1 chainring power meter is close to the values of the Drivo on my next ride.

[Elite Admin S]

Lete me know if now simulation is realistic

Regards

[webmaster]

The power values between the Drivo and C1 chainring are close which is good. However, that doesn't answer why the simulation of the 6% slope is so off in terms of reality.

I don't know how the REAL software does its calculations, but I do know that their is definite errors in them. As I mentioned in a previous post, the distances between the Garmin device and the REAL software are out. In this case now, between 20 and 50 metres over a ride. And this is due to a rounding error per se. Dividing 2096 by 3.43 yields 611.08. So over a 20 or 30 km ride, 0.08 mm is not going to add up to 50 metres. For example, if I am riding at 85 rpm and we have a 1:1 relationship between pedal revolution and wheel revolution (which it isn't), over a 60 minute ride you have 5100 pedal strokes. Mulitply that by the fraction of 0.08 you have 408 mm.

I wouldn't expect exact distances between the two devices, however, like the power devices, they should be close.

Further info Jan 16: I did a ride this morning and the distance discrepancy over the 30 km ride was 140m! That is a huge difference. The only thing I can think of that would cause that given the trainer is sending out the same signal to the 1030 and the laptop, is that the laptop is dropping packets (and it seems a lot of them today). That means that their is a problem with the ANT+ device driver or the REAL software not being fast enough or smart enough to grab all the packets and place them in a queue to be properly processed.

[mgfjd]

I have the same problem. The road simulation slope is a lot harder than real. I lowered my rider weight by 20 lbs - 25 lbs and the simulation feels much better. I weight 185 lbs.

[mgfjd]

The calibration in my drivo is 6420. Serial 52111. The power seems to work as expected.

[webmaster]

I guess by the lack of response to the information that I and the other person provided means we are out of luck in solving this problem.

Pitty.

[mgfjd]

I actually made a connection change and an outdoor test.
I am using an USB extension cable about one foot or closer. It dramatically improved the trainer connection.

I tested with my power meter in a 13% slope outside and compared the results with my trainer simulation. The outside power was 490w, the trainer simulated was 500w. So it's closed enough.
I hope this helps

[webmaster]

I have the computer 150mm from the Drivo (basically sitting right next to the handle bars).

There is something wrong either with the software or the Drivo (I suspect the software actually now). On a training right yesterday with the program set to zero slope for 40km, there was a 400 m difference in distance between the Edge 1030 odometer and the Real software. How could that be? Both the computer and the Edge 1030 are receiving the same signal from the Drivo.

I have seen discrepancies in earlier versions of the software. For example, at the 60 minute mark your distance would be say 30.3 km however your average speed was showing 29.9 km. Huh? How could that be?

I know they are using a formula to calculate the wattage resistance based on slope, speed and weight (I am not sure what the formula is, however, there is one as I did discuss this topic with one of the engineers at the office a few years back). I suspect they are making some assumptions incorrectly such as bike weight (it is strange they don't ask for bike weight because different bikes weigh substantially and can affect the calculations).

A lot of these issues don't make any sense whatsoever. Like the right yesterday, it was almost a carbon copy of my ride from Sunday. The speed and distance were almost to the second, so how could there be a 400m distance discrepancy? The silence speaks volumes.