I don't think it will work well as a high output piece that will breathe fast enough to deal with climbing. You'd be better off with a merino or synthetic base layer and then just stash this in your pocket for the descent.

I'd direct you to check out the Accelero Jacket for this use. The Celeris is my go to for the descent on bikes (it packs to about the size of an orange) I wear the Accelero with an Arc'teryx Motus for cold weather and can wear it up and down. The Celeris breathes well, but not as well as the Accelero, but offers a bit more wind resistance.

Thanks to everyone for the advice. I'll take a look at the Accelero. I live in the high desert of New Mexico, and in the spring and fall I don't sweat that much on the climbs (or it evaporates quickly), but the downhills can be quite chilling. Two layers, no matter how thin, generally seem to be too much.