Rollers

[still-chasing]

Anyone out there using Kreitler 4.5? Need Help with setting up values for Kreitler 4.5 rollers. I'm Using the default values and the perceived effort is different from road feel. thanks!

[travispape]

The manufacture data for the Kreitler rollers is good, but they didn't include the effect of rider weight. If your weight is significantly higher than the person Kreitler used to make there table, then you will have more rolling resistance and vice versa. Tire make & model can also make a small difference. The good news is that both of those can be adjusted by tweaking the value of the B coefficient. Here's how to do it:

* Open the Trainer Settings window
* Click the "Rollers" tab and choose all the appropriate settings, including your 4.5 drums
* Click the "Coefficients" tab and adjust the value of "B" until the power at a given speed matches your perceived effort.
* Click the "Save" button to save the results
* Click "Send to iBike" and you should be all set.

Also, note that you can minimize any errors caused by the weight by increasing the amount of fan resistance if you have the fan. The fan resistance is independent of rider weight, so the more fan resistance you can use the better the overall accuracy.

[still-chasing]

Thanks! I just saw on Kreitler's page their watt result is from a 160 lbs rider. I weigh 138 lbs. Do you have an idea how much to tweak it by? Thanks again.

[travispape]

Thanks! I just saw on Kreitler's page their watt result is from a 160 lbs rider. I weigh 138 lbs. Do you have an idea how much to tweak it by? Thanks again.

Subtract 1.06 from whatever you have for B
If you happen to be using the trackstand option, subtract 0.67 instead.

[still-chasing]

thank you!!

[lorduintah]

Travis -

Perhaps when something like this shows up - would it not be useful to have a short explanation of how you get these values to plug in - it just leaves it as an open item - I am sure the is a coefficient function that is associated with the reistance models...

Tom

[travispape]

Travis -

Perhaps when something like this shows up - would it not be useful to have a short explanation of how you get these values to plug in - it just leaves it as an open item - I am sure the is a coefficient function that is associated with the reistance models...

Tom

Kreitler published an Excel spreadsheet breaking down the resistance by the various sources: drums, fan, flywheel, forkstand option. I scaled down the B component of the drum (and forkstand if he has it) according to the difference in weight between the riders. The B components caused by the fan and flywheel would be independent of rider weight so I left them alone.

Does anyone know if Kreitler still has their spreadsheet online somewhere? I have a the copy they published a while back.