Everyone seems to speed match their locomotives a little different. There are a ton of theories and opinions on the subject, I am not getting into any of those. I am just going to show you how I quickly and easily set up mine and have great results doing it.
I will start with a few points. Every locomotive is different. Not matter if you have the exact same brand and model of locomotive and DCC decoder, every one will run slightly different. I do not get super detailed and use speed curves. I have found that using the basic 3 speed control works just fine.
I use Digitrax decoders in all my locomotives. This is not to “speed match” them, but to have consistent settings. I have found some decoders do no have the same settings which makes this process a little difficult. Also some decoders do not change settings until power has been removed and reapplied. Digitrax is real time when programming on the main.
I run advanced consisting, which has a slight “quirk” in digitrax decoders. When not consisted, the locomotive will run fine. However when you advance consist, the locomotive will run at half or slower speed. To fix this, set CV 57 to 102.
The next thing I do is put the locomotive on the tracks and let it run for a couple minutes to “warm it up”. To be consistent, I make two passes with each just to make the warm up time the same. Then I hook up a gondola outfitted with the Boulder Creek RollBy Onboard Speedometer. This has the advantage over a speed tunnel by giving constant speed updates in real time on your phone.
I decided that I wanted 50mph to be the max speed on my layout so that is what I set the max speed on the decoder as. That forces me and anyone running on my layout to never exceed the speed limit. (I am just as guilty as anyone.) At this point I turn the throttle to full speed and watch the speedometer on my phone.
I then use JMRI to adjust the Max Volts until I get to 50mph.
After Max Volts is set, I slow down the the throttle to 50% and adjust JMRI Mid Volts until the speed is 25mph.
And finally, I power the throttle down to about speed step 5 and adjust Start Volts to where the locomotive just barely starts moving.
That’s pretty much it for the actual speed matching part. I don’t get real detailed on the volts, I usually adjust by 5 or so just to get a consistent speed that is close. One thing to note, the speed will change on corners and grades, so keep that in mind.
The last step I do is set the momentum, or the acceleration rate. I like to run pretty prototypical and don’t like fast starts and stops, so I max this rate out, which on a Digitrax decoder is 31.
All told it took me about an hour to go thru my entire roster, about 20 locomotives. And here is a video showing the results, manned helpers consisted with the front power on a coal train.