Heart rate monitor on F235 is a disaster

If intervals not good, then steady pace will be bad too. I am using 225

Do be cautious in commenting about how well a watch you don't own actually works. You might inadvertantly mislead others into thinking something is true when it isn't.
What I've seen with running intervals and the 235's oHRM is that it shows a marked smoothing lag above and beyond the normal cardiac lag that's normal physiology. This is most evident in short intervals as would be expected.

As for steady state running(*), my 235 has been fine. I've worn it in parallel with my 920xt and HRM-RUN a few times and am quite satisfied with the results. Perfect HR trace every time? Nope. In contrast I've had plenty of troubles with chest strap HRMs over the years too; poor initial readings, dropouts, noisy/spiky in cold weather, static interference, power line interference, etc. Oddly enough those issues haven't prevented me from achieving my running goals.

With all that said, when I do intervals I'm going by perceived effort or pace, not HR. So for me any HR smoothing lag during intervals is immaterial. If your training is specifically focused on HR zone short intervals you may want to supplement the 235's HRM with a chest strap. (not sure how you deal with cardiac lag though?)

Interesting article I ran across yesterday: 3 Common Heart Rate Training MIstakes by Matt Fitzgerald
Mistake #2 is "Using A HR Monitor in Speed Workouts" :)
Link: http://running.competitor.com/2013/12/training/3-common-heart-rate-training-mistakes_29427/3

(*) as "steady" as running in a fairly hilly area can be... :)

Do be cautious in commenting about how well a watch you don't own actually works. You might inadvertantly mislead others into thinking something is true when it isn't.
What I've seen with running intervals and the 235's oHRM is that it shows a marked smoothing lag above and beyond the normal cardiac lag that's normal physiology. This is most evident in short intervals as would be expected.

As for steady state running(*), my 235 has been fine. I've worn it in parallel with my 920xt and HRM-RUN a few times and am quite satisfied with the results. Perfect HR trace every time? Nope. In contrast I've had plenty of troubles with chest strap HRMs over the years too; poor initial readings, dropouts, noisy/spiky in cold weather, static interference, power line interference, etc. Oddly enough those issues haven't prevented me from achieving my running goals.

With all that said, when I do intervals I'm going by perceived effort or pace, not HR. So for me any HR smoothing lag during intervals is immaterial. If your training is specifically focused on HR zone short intervals you may want to supplement the 235's HRM with a chest strap. (not sure how you deal with cardiac lag though?)

Interesting article I ran across yesterday: 3 Common Heart Rate Training MIstakes by Matt Fitzgerald
Mistake #2 is "Using A HR Monitor in Speed Workouts" :)
Link: http://running.competitor.com/2013/12/training/3-common-heart-rate-training-mistakes_29427/3

(*) as "steady" as running in a fairly hilly area can be... :)

I had to laugh at your last comment - I'm surrounded by hills myself. I did experience the annoying cadence lock issue when going up and down a set of short rolling hills which was bit annoying as it was a long run and while I wasn't training by HR I do like to keep an eye on it, especially during long runs. So seeing a HR of 178 or something when running downhill at easy pace was a bit off-putting. As I posted earlier in the thread I have started to get somewhat better results doing short intervals by wearing the watch in a different position. I suppose I mainly use HR to ensure that my easy days are easy, and for the most part it does that. I would say if your training is specifically focused on HR zone short intervals forget about optical HRMs because you won't get the level of accuracy you require. I do think with a small bit more work Garmin can get this watch to a state where it is fairly accurate during short intervals - at least as good as the competition. Each user should be aware that there is probably an optimum position for the to wear the watch during these intervals that is not the same for everyone. I don't depend on HR doing short intervals - I go by pace, but I like to see the HR afterwards to see if the effort was enough or too much so I can tailor the pace for my next workout, so I'll wear a strap in future for these workouts,

I do think with a small bit more work Garmin can get this watch to a state where it is fairly accurate during short intervals - at least as good as the competition.

Yes, lest anyone misunderstand my position, I certainly think Garmin has plenty of room for improvement in the 235's oHRM. It's by means perfect, or even the best execution of the technology. Especially in the case of wrist-worn oHRM.

It does, however, do what I need it to do within the expectations I have for it given my understanding of the technology and its limitations. A big plus of the 235 is it's ability to use an external HRM when the situation calls for it; essentially the best of both worlds, skip the wet/cold chest strap for steady runs, suffer putting it on for the HIIT workouts or other stuff wrist-worn oHRMs aren't so good at handling.

Question for those doing intervals; check to see if you're tensing up your forearm/wrist when pushing into the interval. If you are, try making sure you don't tense up and see if you get a different result from the oHRM. These work by measuring how the light reflectivity changes as the blood volume in the skin changes due to the pulse pressure waves. I wonder if tensing up might affect things?

As for cadence lock, I've really not noticed it except maybe once or twice, briefly. I wonder if the foodpod I use may affec t that? I suppose I could try some runs without it, but to be honest I'm not curious enough to mess with it when what I have is working okay... :)

That's a good call on the tensing of the hand while running. I noticed this when it was stupid warm on Christmas Eve and I was carrying my shirt during the latter part of the run. Whenever I switched it to my right hand (the side I wear my watch) the HR reading would be off, but when in my left hand it would be fine.

https://connect.garmin.com/modern/activity/1005960387
I broke down and bought the Garmin deluxe HRM today. Was getting poor HR results with the 235 at the track, didn't track properly or would be too high or too low. The HR strap gave me very good results today after warming up a bit, didn't have any gel. Luckily I had a store credit that paid for about half the price of the strap so didn't set me back too much. Seems very comfortable and makes a nice HR graph on strava so I can finally see how my HR is recovering between intervals. Will still use the 235 optical sensor for regular steady pace runs. Also I like seeing the sleep data and my resting HR.

A question for those having trouble - do you wear it 24/7 or just for activity? I've found that it reads a lot better if I've had it on all day before using it as opposed to picking it up off the charger and going. It seems like having it on all day pushes a dimple down into my skin that the watch sticks in and it makes the sensor read better with less light interference. If I had just put it on after charging or something else, it slides around lot worse and doesn't stick down in my skin as well.

A second observation is that *turning the top of my arm/wrist away from me* slides the watch from its position and definitely affects the HR sampling ability. Laying in bed in the dark I can clearly see the green led start shining out when I twist my arm to look at my palm. When I rest my arm back to flat, the led light is gone. So if you're running and turning your arm for some reason - like if you're exercising with hand weights, or twisting your arm to position your water bottle, or just running with your palms facing up because you're weird ;) - it could impact the HR sensor's ability to get accurate readings, or even any reading at all.

Overall, I've had pretty good luck with the HR on runs thus far when I remember to tighten the strap 1 extra notch before I start. It took a few weeks to get into the habit of it. Occasional cadence lock issue, but it doesn't usually last long. Never had it fail to record any HR at all. And it's actually done a better job keeping up with changes in HR on intervals than I expected from the reviews.

Overall, I've had pretty good luck with the HR on runs thus far when I remember to tighten the strap 1 extra notch before I start. It took a few weeks to get into the habit of it. Occasional cadence lock issue, but it doesn't usually last long. Never had it fail to record any HR at all. And it's actually done a better job keeping up with changes in HR on intervals than I expected from the reviews.

Have to agree with this. I see the cadence lock in my runs when my HR and cadence get close together about 50% of the time, but it never lasts long and the watch figures it out. I'm pretty sure it's a noise filtering issue that can be fixed with a software update, so i remain hopefully.

Regardless, overall the HRM has worked really well for me and my experience so far with the watch as a complete package has been overwhelmingly positive.

https://connect.garmin.com/modern/activity/1006885084

Had great results tonight. No cadence lock. HR tracked very well. No problems and I wouldn't expect any better from the Mio. Wore the watch on the outside of my right wrist a bit higher up than usual and a bit tighter than usual - the bad left an imprint, but it wasn't uncomfortable. For the record I'm male, fair skinned, not very hairy and whatever hair I do have on my arms is practically white.

Mine is also hopeless for HRM tracking when running, indoors or outdoors. Used it for a month.

I replaced my FR225, which was also totally useless (and was replaced 3 times for various failures in 5 months).

Should have bought a 630, and just got on with the strap! Garmin seem to have constant issues with HRM - straps or watches - they need to get a grip. Never had an ounce of bother with any HRM from Polar, although been a Garmin user solidly for the last 5 years.

Brian.