Would a Helly Hansen warm be too hot for MTB ? Would I be better off with a dry for between 0 and 5 degrees?

Dry would be more than adequate.

If i remember rightly the warm ones are rated for minus 10 and below.

Mine only gets used for riding when it’s below freezing.

I wear mine all the time biking. Depends on what you have over it – I wear it like a jersey. Under a windproof or waterproof, yes it is a cool day.

Worn my warm once for MTB, got way too hot. But then I don’t feel the cold.

It’d probably need to be below about -10 before I considered it for MTB. Even then I’d maybe layer more.

It is excellent for post ride cosiness though. And walking isn’t as warm, so good for that.

I like mine for cool days. Have two types of helly warm baselayers though, one is a merino blend, one is more like a thicker version of a lifa. both very good under a thin softshell

I was looking at the merino blend and planned to wear it either on its own or with a thin shell over the top. Will look at a dry crew

They are v warm. Only ever been cold enough once to wear mine on a bike.

I wear the warm ice crew quite often, works well on colder days with a waterproof over it. Good for an average Scottish winter ride.

For colder days I have 1/2 zip freeze HH base layer which is a little thicker. This plus an Endura Stealth is good for sub zero stuff

I wear mine on its own quite a lot on cooler days. but I run pretty cold, normally need a few layers and was fine with this as a single layer. They are amazing though.

I have one of their revolution dry baselayers too. Its a very light stretchy material, looks a bit gimpy. But its much better than the plain lifa tops