As my course preview reveals, K78 is not normally anything like some extreme mountain races, where heavier trail shoes are preferred by most runners. As a rule of thumb for European races, if poles aren't allowed, then flats like ST4 should be ok.
Few racing flats are flat, and ST4 is not an exception:
- midsole height: heel 22 mm, forefoot 10 mm, ie.
- heel-to-toe offset 12 mm.
I've done the K78 a couple of times before with Racer ST3. Scott Jurek, who is sponsored by Brooks (unlike me), had won the 246 km Spartathlon ultra marathon in 2006 wearing a pair of ST3's. He was actually able to do that for three years in a row.
So in 2007 I ran my first K78 with ST3's. Finished in under ten hours as planned (9:43), I was happy with that.
In 2008 I made several mistakes and DNF'd. That was the year when I covered an ultramarathon distance once every week. I managed to run 47 km before they stopped me, so I had my ultra for that week done. The main reason for my pitiful pace was my Salomon trail shoes. My feet had been hurting a lot that year, because that's when I got the crazy idea of running with trail shoes. I also had a pair of The North Face Rucky Chuckys, but they were not much as far as my feet were concerned. It took me months to realize that my injuries were directly caused by wearing robust stability/motion control/trail shoes.
In 2009 I was back with vengeance and a new pair of ST3's. I was rewarded with a course PR (8:56).
So I've ordered a brand new pair of ST4's, which should be the same as ST3, except some minor modifications in the upper of the shoe. I hope they have changed the laces as well - I hate the laces in ST3. I don't know why, but they they don't work well for me. [Edit: Yes ST4 sports improved laces and lacing system. Well done, Brooks!]
By the way the latest blog by Anton Krupicka is interesting. It's about his training run in the high altitude of Rocky Mountain National Park with Scott Jurek. The photos (by Jenny Uehisa) show Scott wearing ST4's! Jurek is training for UTMB next month, and who knows may be brave enough to consider racing it with them. I think he has been wearing Brooks Cascadia trail shoes in his previous attempts, which have more or less failed. Wouldn't it be fantastic if Scott beat Kilian Jornet and Geoff Roes wearing ST4's!
Alright that's enough speculation, more to come after some real results.