Perfect time to forget about base training an improve your run speed and strength. Three months of speedwork and hill work on your T-mill will do wonders come Springtime.
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so your suggestions is to do a 180 turn?
(I also started with this approach (more easy runs) based on a lab test last summer where the doc indicated that my base seems slightly underdeveloped. And on top of that I'm fairly injury-sensitive; like I said, I think I ussually have decent speed without speedwork ... don't see myself running a <35min 10k in a 1/4 distance tri (would be nice though)
For last year my avg. speed was appr. 4.30; which is upper Z2; with very little speedwork (sometimes some shorter tempo blocks (~3.40) ... not sure whether there is any real purpose of any real speedwork??

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At some point along a persons training life "speedwork" is not about getting faster but instead it is about trying to stall the inevitable slowing down.

point taken :-)
Well my (run)training life is not that old yet at ~3 1/2yrs ... my other age is on the wrong side of 40 though.
Have never done a single week longer than 55km yet therefor thought the consistent 4 - 4 1/2 weeks I seem to handle now on the treadmill could build me a nice base before spring.

Living in Canada I'm doing 99% of my running on the treadmill until March. I've personally found that for me volume is king for running (vs intensity). I say get the miles in on your treadmill and you won't miss a beat come spring.

I despise the treadmill.... do all my runs outside (and I live in Canada) like I have for over 40 years..... that said, if you will run more and be consistent by using a treadmill then it is a good thing.

good two hear 2 other opinions as well; thanks
I also prefer running outside in nice weather; however with Netflix etc. I have no issues at all with tm (actually look forward to it sometimes to continue with a series I'm watching :-) )

Regarding consistency; I def. have the idea that I can run more often.
On the one hand due to lower speed/impact I guess (on the road I always tend to drift to 4.25 or faster no matter what my idea is (basically end up atleast in mid Z2 in all my runs ) ... treadmill is set and forget, can easily stay in low Z2
furthermore due to work/home circumstances often the best time for me to run is around 19pm (so not too long after dinner) ... for some reason, I need more than an hour to properly run outside without issues after a big meal

I think that you nailed it right here - in the winter, run outside if it's nice but otherwise run on the treadmill to maintain consistency to build that base. Sounds like you've got a great plan!

I don't know about getting diverted by netflix on such short runs. As Nick said, if your runs are that short, mix up the pace and inclines, focus on form and the technical aspects and it goes by quickly. And as Allan said, many live in bad weather in Canada and only run outdoors. Aside from the days of freezing rain or a foot of snow, its always pretty doable (I started the first 100/100 on ST and it was 100 days in a row, every day, outside regardless of conditions). The other benefits of running in the real world regardless of conditions is that racing is in the real world regardless of conditions. I have found in the past that my athletes who embraced real world weather performed better in racing in adverse conditions. They know how to adapt and work with the variations of nature since they can't control nature. It is subtle, but since you are always working around nature, you know how to adjust without even thinking, because you did it 100 times. The mentality applies whether natures throws snow, wind, rain, heat, ice, sleet....whatever comes.

As you are fairly inexperienced athlete, I would say there are gains to be made there. If an athlete like Allan says he wants to do half his workouts on bad days on the treadmill, I would not be that worried, because he has a lifetime of experience dealing with the real world in training and racing. You can always modify the type of run depending on weather, just like you have to modify the type of tactics in racing depending on weather.

That is indeed my biggest concern that I'm not used to running outside anymore come early spring ... for some reason the pounding seems way less would this mean my legs don't get the "hardening" either? I'd still have 4 months of prep for my 70.3 though. (not really worried for the 10k's in a 1/4 dist. as I am fairly sure I can run a decent time even without any dedicated tempo work). I hoped to do some BarryP derivative plan with a 100/100 alternating 30/45-60 min runs 7days/wk; this would def. increase my hours by 25%.
Alternatively, I would be doing 3-4 runs/wk so equation is not that straightforward maybe?

regarding the inexperienced athlete part; well that would be true for the "tri" part however I started bike-racing last century :-) and endured my share of mediocre weather; at that time I even was able to extract extra motivation from bad circumstances ... guess I've become soft as I aged and with all nice indoor tools available nowadays:-D

Oh, OK if you have a lifetime of sport in good and bad weather then disregard what I said. For the same reason I am a fairweather cyclist now. I know how to deal with bad weather at this point in racing, so I don't need to practice it weekly.

In terms of hardening your legs, no, there should be no big transition even if you spend all winter on treadmill. You should be fine in a 6-10 days. But if you say treadmill vs outdoors is a massive delta in pounding, I would check how much you may be overstiding. Maybe your hamstrings are less engaged and you're not already pulling back back and activating with glutes and you're doing lazy treadmill running and letting the treadmill do that for you (in theory there is zero delta between treadmill and road in terms of what happens, but in practice treadmill is perfectly fixed speed of body relative to belt, but on road there is small variation of acceleration and deceleration of body relative to pavement on each stride and the faster you go, the more this is because fast running is connecting a series of bounds which implicitly means more deceleration while in flight vs slow running).

What about all bad weather days on treadmill and all good weather days outdoors. Best of both worlds.

Noticed indeed that my cadence was lower on tm (~165 vs 170+ outside) maybe due to lazy style indeed?! At faster pace this seems less the case though.
For intervals I think I'll do them with max. incline. As to me higher speeds feel scary for some reason (also wussed out at my lab test last summer at 22kph as I was just afraid to hit the deck at some point )
Will probably mix it up indeed with outside in the end, just can't do the 100/100 then ... am not really much of a workhorse in that regard.

As I'm just past half-way on the 100/100 time time for an update.
Up until last weekend I ran a total of 2 runs (30 mins each) outside this year and did all my other runs on treadmill, with 4h30 / wk of which 90% on very easy pace (Z1, appr. 4.50/km I guess); and occasionaly some short bits (1km) at max incline. Max length of these runs was 45m - 1hr once a week, with most of them at 30mins.
So last saturday was the time to do an outside test and this went surprisingly well, planned to try a HM at 4.00(km) pace; however first 10 went by at ~3.50 while still feeling quite relaxed so then I upped my pace a bit to try for a time under 1h20 which I barely made. Until km 17 all was very controlled only the last couple km's I started to struggle a bit (either because this was my longest run post-covid or because I hadn't done a single km this year at the pace I was now holding :-) )
Basically this could mean 2 things; (1) all these short and easy TM runs do build the base required and speedwork is overrated or (2) I have not hit my potential HM time by a long shot (which I can't really imagine)

So true!

I normally run on a treadmill or indoor track throughout the winter months.

It never made me a worse runner.