Jeff,

I've used my Montbell Tachyon windshirt or my Patagonia Nine Trails windshirt for temps below 60F when it's cool and wind is present. Above those temps for me I find I need very little in the way of wind protection as the air temperature at that range is comfortable. Windshirts are quite different than nylon button up hiking shirts which are far from windproof, rather they're intended to be layered over a baselayer, midlayer, or insulation piece. I wouldn't use the Tachyon against your skin if you're on the go, it would stick to you Glad like Press and Seal, become clammy, and likely feel like you're wearing a trash bag. Can you use the Tachyon at 70F? I suppose so but 70F is rather "warm", if it were a cool 70, overcast, with wind present, I believe the Tachyon would nearly cut all the wind and breathe well enough to keep you comfortable. If you're moving again, I'd find the Tachyon too warm and would likely throw it in my pack.

I just received the latest Japanese MontBell catalogues: the 7 denier fabric used in the Tachyon is also used in a full-zip jacket (65g for a men's jacket) and a vest (45g for a men's).

Will said:

For me (6 ft/1.83 m, 170 lbs/77 kg), the Tachyon Anorak and Dynamo Pants in size Large are a perfect fit.

Eugene said:

I found the fit to be typical of Montbell products, for me (6',170lbs) a Medium fits just right in all areas and allows me to layer over my Montbell UL Down Parka.

Could this be resolved, please.

Also, how badly does the Tachyon flap in the wind, given that Eugene can layer it over down?

"Also, how badly does the Tachyon flap in the wind..."

Wearing a baseball style cap...
At 40+ mph it is hard to hear.
At 10 mph it is not to bad.

Wearing a thick knit stocking cap, and adjusting the hood, you could probably quiet it down quite a bit.

John,

I should explain briefly and will try not to speak frivolously for Will. It's been my observation in Will's articles and reviews that he sizes up on his shells considerably to accommodate being worn over winter down gear, which is also sized appropriately to be worn over his mid and base layers. I purchased the Montbell Tachyon with the intentions of only layering it over a thin BPL Beartooth Hoody, and my Montbell UL Down Parka which has a very low baffle height and slips neatly under a wind shell without compromising down loft or warmth. If for example I owned a Nunatak Skaha down parka for winter use I'd definitely size up to a Large in the Tachyon.

Also, I prefer my garments to fit slim rather than roomy, just my preference. This may explain the size fluctuation. Preference and function.

Thanks, Greg and Eugene.

I had a pair of these wind pants. Wore them during laundry times on the Hayduke. Also took to wearing them every day on a cdt section this year.

The fabric at the inseam wore out after about 500 miles. I was always mindful of them as I knew such thin fabric couldn't stand hard use. No pushing through brush or rock climbing.

That said, I've worn holes (same place) in rail riders pants in about 1k miles... They weigh about four times as much.

These were very comfortable. Packed tiny. Light enough to take as "town clothes". I just hope that next pair I buy I can stick to only wearing around camp and while doing laundry because every day wear I would happily use up a pair every month or so on a thru.

--Bill

Will, well written and fun-to-read article. Definitely makes me want one. Anyway, I am in the same camp as Jeff. He lives in Central CA and I live in SoCal. We both like the Sierras and so we probably see fairly similar three-season walking conditions. Trail walking and adventuring this year I often wore a l/s Exofficio shirt of similar design to what Jeff is talking about above. It was excellent at blocking sun and mosquito protection and also provided added warmth when an insulating layer was too much. I carried it everywhere and often just slipped it over my base layer (s/s t-shirt) and found it to be a must have. Really good when walking on granite too to provide sun protection. My question is, can this Tachyon Montbell wind shirt or the other Montbell products of similar fabric weight be substitued for the Exofficio? I do not have that Exofficio shirt anymore because it was a loaner. I even tried to buy it from my friend, but he didn't want to sell it! I need to make a choice now. Will the Tachyon or UL Wind Jacket be breathable enough for Jeff and I? And do you know if it has any sun-blocking qualities and if so would you care to venture a guess? Thanks for your help Will.