# Turbo trainer overestimating speed

I have just started using a trainer, Elite turbo muin B+, the power, cadence and speed are transmitted via the Elite misuro B+ sensor.

The issue i am having is that the speed is being overestimated. I know from my experience of many years of cycling and what i am capable of that the speed shown is too high, the cadence and power output seem about right.

Does anyone have any ideas or experience of this and any possible solutions to rectify this to give a more realistic indication of speed.

The sensor is set to 12 blinks as per the instruction.

• Are you looking at KM where you might be used to looking at MPH Jan 29 '20 at 15:07
• Is the trainer calculating speed or simply transmitting it? Your IRL (on road) speeds will be considerably lower due to air resistance. On the this style of trainer you are not overcoming any air resistance (either from your bike/body, or from spinning wheels). If the trainer is simply translating your speed in vacuum (how fast a wheel would be spinning), it might be correct. Jan 29 '20 at 16:38
• Why would a trainer 'estimate' speed? Speed would be calculated from direct drive axle angular velocity and approximation of effective rear wheel radius. That should be the easiest and most accurate thing to measure. Jan 29 '20 at 20:00
• Isn't your speed on a trainer 0km/h? Jan 29 '20 at 21:02
• @ArgentiApparatus With many trainers such a number is pretty much meaningless, depending how the resistance reacts to that speed. Some trainers have adjustable resistance, somewhere you only change the gears and resistance grows with the speed on some (to the user) unknown curve. It does say how fast your wheels are turning, but the trainer may want to report a speed that could have something in common with the power output and an average road bike at certain road inclination. Jan 30 '20 at 9:34

I would expect that riding in a trainer would result in a different average measured 'virtual' speed than you would see riding on the road. The speed/resistance curve of the trainer will not match the actual speed/resistance curve you experience riding on flat ground in real life.

In any case, I don't think the virtual speed actually matters. What you would pay attention to is the estimated power. Unfortunately it seems like these trainers have power estimation problems.

http://www.olympum.com/sports/the-curious-case-of-mr-elite-turbo-muin/

• True, although the OP says their power numbers seem about right. I am assuming those numbers are "known" from other sources, indicating that perhaps the trainer is working fine. Jan 30 '20 at 15:45

Unfortunately this trainer has wide spread accuracy problems, and it is quite likely that you will not be able to get it to report accurate data.

The problem comes because it doesn't measure power directly, it estimates it from a resistance curve.

A quick google will show MANY users having this problem. Here is one example from Elites own website:

http://www.elite-real.com/en/forum/turbo-muin-smart-b-wattage-indication-too-high-high-resistance

• OP states power and cadence are normal and refers to speed being incorrect, I would have thought speed would have been calculated using power over elevation and time but I'm not familiar with that trainer Jan 29 '20 at 15:40
• @DanK The OP said power 'seems' correct, but didn't specify it was checked against an accurate power meter, so is probably not actually correct. Whilst being a direct drive, rather than wheel on, it is basically a 'fluid' trainer which are prone to all sorts of measurement errors. Jan 29 '20 at 15:47
• @DanK Speed would be calculated from direct drive axle angular velocity and estimate of effective rear wheel radius. That should be the easiest and most accurate thing to measure. Jan 29 '20 at 19:37

All that really matters is that the measurements are consistent. What is 250W, its just a number. What is 30km/h - just a number.

Think of the numbers coming off the trainer as being that - just a number. If you need to compare it to your road bike, you need a conversion functon. "Actual speed km/h = fx(Trainer 30km/h`)", and work out though measurement and experimentation what algorithm to use for fx(). IN the real world we have two systems of numbers and a simple fx() and no one bats an eye.

If you are doing it for training, all you need to know is your performance and how it is changing, for this, you just need numbers, and as long as the trainers numbers are consistent no need to worry about how they relate to the real world.

Real world has things like physiological effects of wind that actually cools the body and phycological effects such as levels of interest and boredom or fear of the large metal objects hurling towards your at 100km/h that impact different riders differently. Add differences in road surfaces and rider position, and there is no way a trainer can provide accurate numbers for everyone. Best they can do is provide an approximation that is sort of accurate for some people some of the time.