No arm-warmers? No big deal, I used my wicking, long-sleeved running tops for a long time; if it’s below 40, you wouldn’t be removing the arm-warmers anyway.
Same for knee-warmers; running tights over cycling shorts work fine if you’re not entering a cycling beauty contest (which is really hard to win when you’ve got snot dripping out of your nose).
My rules of thumb:
1. LAYER, LAYER, LAYER
2. Keep core, ears (head), hands and toes as warm as possible. When they get cold, misery quickly follows.
What’s the right combo for which temperature? It’s a recipe that’s highly personal, but here’s my very quick reference guide:
Armwarmers OR longsleeve (LS) running shirt, jersey AND undershirt are good. The closer to 40 the temp is, you might want to add a wind vest. Kneewarmers or long tights. Two thin pair of wool socks, if it’s not too tight in your shoes (preventing good circulation with tight shoes makes your feet cold faster!). Thin gloves, you can double up with a cheap pair from Walgreens and shed as needed. Ear coverage recommended.
Same as above, definitely layer gloves, closer to 30 degrees, I highly recommend wind-proof outer gloves. Add toe or shoe covers. Duct tape over those shoe vents that are so “helpful” in the summer. Consider a thin hat that fits under the helmet; good for colder temps. Also, at 30 you’ll want something covering your neck, too. Balaclavas are good all-in-one options. Layer socks again, we love these long wool socks from Defeet. Wind vest is a must and if you’ve got wool arm warmers, no sleeved jacket is necessary yet.
Cover everything you can:
hat, balaclava/neck gaitor, layer gloves (yep, those dorky lobster gloves are critical), as many socks as you can handle to keep blood flow good. Multiple layers on your core: undershirt (I wear a tank and short-sleeved ones), one or two jerseys or LS running shirt, lightweight wind-jacket. Arm warmers, knee warmers. Add a layer of tights, too, if it’s closer to 20. Glasses to protect your eyes/face from the wind are critical.
10-20 degrees: Hit the MTB trails or wear a ski mask. The wind in your face at 20mph is not fun or recommended. MTB riding is slower and usually requires more effort more often, trees shield the wind, etc. If it’s this cold, I suggest using just about everything you’ve got and just pile it on (I’m a wimp!). Also, those packets for hand and toe warmers are invaluable at this temp.
It’s a rough guide and a few degrees (when it gets in the 30’s) can make a bigger difference than expected. Test yourself with shorter rides, or rides where you know you’ve got transportation alternatives if you need to bag it.
Whew, now I feel like I need some good ol’ hot chocolate. I’m cold just thinking about it!