Your threshold or LT2 heart rate can be estimated by going out on a 30 minute run/ride. You need to do this as fast as possible, if you have a long enough hill so much the better. Warm up then go out hard. Take your average heart rate for the last 20 minutes. You could also look at previous training sessions recorded on Strava that match this protocol. Look for the average heart rate for a 20 minute segment. You could also do this effort on rollerskis or cross country skis, again it is probably easier to get realistic readings on a long uphill section.
However as the above research showed, lactate thresholds will respond to training whereas max HR is much more constant. You can also get your HRmax from previous rides but be careful of random spikes. Your sports computer may also give you a HRmax reading. Otherwise go out for 15 minutes to warm up and then do an all out 3 minute effort, say climbing a hill. Wait for your HR to return to around 120 bpm then do that effort again and note the maximum HR achieved.
For 186 bpm:-
Note: optical armband heart rate straps tend to under-read by a few bpm compared to chest straps and your running max heart rate will be a few bpm above your cycling max heart rate. The same should be true for cross country skiing.