with the 90 degree bend valve stem you can only push it thru in one direction, if the angle will end up pointing away from you, it wont go in
the problem is the stiff tire fights you, you have to push the far sidewall against the far side of the wheel, so there is room for the valve to go thru the hole in the rim, and at the same time you need to spread the sidewall that is not hooked into the rim yet far enough to get your hand in there.
There must be a tool or clamp thing that bike shops use to spread the tire open and do this. Two people could probably do it by brute force.
If you have already pushed both beads over the rim and now you are trying to get the valve stem in the hole, you would have to clamp the opposite end of the tire together with a big c clamp and push it up into the center of the rim, to get some slack / space on the side where the valve stem is.
I changed the tires on my 650 by myself once. Its not worth the amount of work compared to carrying the wheel into a bike shop, and having them mount the tires for $35 to $45 each.
Without the tire mounting machine its almost impossible, esp with a really good heavy long lasting tire, like the OEM Bridgestones.
Last edited by KCW; 08-01-2019 at 09:21 PM.