The Bear Riders that were just outside Bruma in Oblivion, have moved just over the border into Skyrim. I found a location next to the road to the border crossing for the HQ, and added a "Gudrun" and a "Timo" to the staff. The building is an inn, with bedrooms and forge in the basement. The main floor has facilities for alchemy and enchanting. It's about the same distance from Helgen as Falkreath or Riverwood, so it could be a third option for the starting player to head off to join the Riders.
Joining the Riders is only for females. The bears insist on that, and they'll also require the right equipment on the rider. Their special armour can be forged only at the HQ forge, but tempered/improved anywhere. It all has the same stats as the equivalent regular armour of the same material, and is made from the same list of materials. If I can determine how to add a frost protection bonus, I'll do so. Since there's a perk to allow multiple enchantments, there may be a way to do that without blocking the player from adding another.
I haven't found many bears in the Falkreath region in Skyrim, so maybe the bears can come from other places, but the trainer lives and trains the bears in Falkreath? That'll give a little more reason to actually go there...
That was the case with Meija in the Oblivion mod. She lived in Falkreath, and the bears were sent from somewhere else (Solstheim via Windhelm?) for her to train, so she only had one at any time. I'm thinking that the player will have to raise the cost of training a bear before they get one, and the trainer will have a quest to do as well. If I have a "recruit another rider" quest, similar to the recruiting for the Blades, then she'd start training more bears as the candidates join up. There are also possibilities for issues with her supplier, and a whole lot more.
I need to find an outfit for the trainer, that's similar to the one Meija wore - gloves and arm protection, so she doesn't get hurt by roadside foliage, and boots with possible thigh protection for the same reason. Minimal torso coverage, to keep the bear happy, and they also don't like fur or leather in any quantity. Chainmail is OK, as long it it doesn't contact the bear. She'll be a Nord - the 50% frost resist is a must in that outfit - and have an amulet to provide even more. (And it could get stolen for another quest opportunity.)