Hi Dave,
I'm a former Greyhound bus driver who drove that route quite a few times. I've since moved on to Victoria. I've never cycled that route but it is quite winding, steep and sometimes narrow. In some spots trucks and buses have to slow down to 30km/h or risk flipping over or losing their loads. There are some sections where trucks and buses will not be able to get by you (too winding to see what's coming the other way) unless you courteously move over so the poor trucker doesn't have to shift through a whole myriad of gears to get back up to speed
. But the traffic is relatively light and there are some 4 lane sections.
As others have pointed out there is NO ACCOMODATION along the way except the Manning Park Lodge (Quite expensive). The only relatively cheap motels are in Hope and Princeton.
Once you hit the pass the road is surprisingly level for a little while (relatively speaking). Then it's an overall descent but it still has quite a few climbs thrown in for good measure, even though you are losing altitude overall. Make sure you have the stamina for it. Otherwise it's a very beautiful area.
I don't carry bear spray when on highways but I have carried it on the railbeds from Castlegar to Hope and other more remote areas on Vancouver Island. The problem with bear spray is that it's useless unless you know how to use it. And the reality is that bear attacks are actually extremely rare when you consider how many people wander into their territory. I've had 8 close bear encounters so far, including one who snorted at me and one who took a run at me
, only to bluff and turn at the last moment. It's possible that bears might be encountered at the higher altitudes in September. Respect their space and they'll most likely respect your's.
Above all have fun, especially when you're on my turf on Vancouver Island