Forerunner 235 vs Forerunner 725xt

Whether the extra features are “worth the price” difference is subjective, and depends on how much you personally “like the idea”.

There's entertainment value (including the appeal to self-styled data geeks of having access to the statistical “information”, which may or may not actually be accurate), then there's value as an enabler if the user's key objective is to continually improve through responding to actionable insights (which the stats may or may not allow him or her to form); they are different things to different people. Furthermore, what is (say) $200 “worth” of either entertainment value or performance improvement (or a combination of both) to the individual?

The Forerunner 735 is simply a better watch, with regards to battery life and features. I had a lot of problems with the battery on my 235 and when I got a 735 on sale I was very happy with it. However, note that you'll have to get the HRM-Run strap or possibly the RD pod to get Running Dynamics.

Actually, I'm not sure that the extra metrics are worth a whole lot, though the HRM strap is nice and the HR data is solid. I haven't had any real benefit from Ground Contact Time balance, vertical ratio or the rest. There just doesn't seem to be any real actionable data. Training Effect is nice, but the problem is you only see it when the run is complete. it'd be nice to see it during the run, so you can see if you can go another lap or you're starting to overtrain.

Honestly, I've found that Strava's Fitness and Freshness score is as useful as Training Effect and Recovery Time on the Garmin's, and it makes more sense to me.

I would recommend the 735 over a 235, but for the watch itself not the Running Dynamics. If you can hold out you might check on the 645 in a month if the reviews are decent (after the initial firmware bugs are worked out) as it will likely be a better pure running watch + it has a better HR sensor + it looks nicer if you wear it 24/7.

The 235 is a good running watch. All you really need is time, distance and pace. (And maybe the same 3 metrics for your current lap, which the 235 also gives you). The 235, as with all watches from that gen and onwards, supports apps, so various gaps in functionality (like navigation) can be filled that way (except of course, for advanced running stats).

If you really want an advanced running watch with all the extra metrics, I wouldn’t get a 735 today unless you want to do triathlons. For $50 more, I think the 645 is a better option.

advantages of 645 over 735xt:
- 645 has 1 sample per second all day HR monitoring. 735 only samples every few minutes (outside of runs and other sports). If you care about resting HR it might be a consideration. The 235 has similar limitations to the 735, btw.
- 645 has a slimmer HR sensor. 735 has a huge bump which may be less comfortable. 235 is similar to 735 here.
- 645 has a lot of extra features previously only found in high end Fenix watches, such as stopwatch and timer (can even be used during an activity). Sounds silly, but sometimes you want a stopwatch that isn’t tied to a run (Not that it’s worth hundreds of dollars)
- 645 has newer hardware (eg CPU) which basically means that the watch will be more responsive while flipping through data pages on a long run (for example)
- 735 has a max of four custom data pages; 645 is practically unlimited. Four sounds like a lot, but if you use apps, one or two of those can be used up by apps that take up a whole page.

Anyway, all of those things are just nice to have. I used basic watches like the 210 or 220 for a long time (2013-2016) and set lots of PBs. As terrible as the 210 was, I never would’ve gotten rid of it except for the fact that the start/stop button broke (and the battery was getting iffy for marathons).

But if you want a high end running watch, I wouldn’t get the 735 today.

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As far as metrics go, other than pace, I think hr and cadence are more important than anything else, and these are already available on basic watches. For me personally, the advanced metrics are correlated with nagging or serious injuries, but as dcrainmaker pointed out, it’s not clear how to actually use that data. For example, nobody suggests consciously trying to change stride length. Cadence is another story.

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And speaking of Strava’s fitness and freshness score, you can get similar data from strava without buying Premium. The Stravistix app for Chrome (PC/Mac) will give you the same info if you visit the strava website on your computer.

Training effect and lactate threshold are fun to look at, though. If you take the lactate threshold numbers seriously, theoretically it could help you train at the optimal HR for increasing fitness. Then again, some people get that measured in a lab....

I actually also like Performance Condition (which sorta tells you whether your workout/race is going to go well today), although many people hate it.

bfischer86 wouldn’t performance condition be the real time equivalent of training effect? At least in the sense of “Can I keep going or not?”

Training Effect is nice, but the problem is you only see it when the run is complete. it'd be nice to see it during the run, so you can see if you can go another lap

As far as I can recall, Training Effect is one of the available data fields on the FR235. I have that data field on one of the customisable data screens on my FR630 when I run (outdoors), and the value in that data field changes unidirectionally as each run progresses.

@bfischer86 wouldn’t performance condition be the real time equivalent of training effect? At least in the sense of “Can I keep going or not?”

No. Try not running for three or four weeks and then go for a run, and your Performance Condition would probably start with a negative value and progressively decrease, even though you've barely run 2km. I've achieved PRs on runs that my Performance Condition started off at 0, and did far better than when on the same route my Performance Condition was reported as +5 (at the same point on the route, about 1km into the run).