With all PVC extension pieces inserted the bike chain can be some 40" above ground, at this height a lateral support is needed.
Tie the vertical pipe to some fence post, wall etc.

Step 1: The Parts

All parts are PVC 1.5" plumbing pipe with exeption of grey fittings which are electric non-metallic fittings. Mouse over for desciptions of parts.

Step 2: Bike Bar Holder

Image 1. The Bike Bar support created from 1.5" tee cut to create opening for bike bar to be inserted, hinged with a piano type hinge, rivets used. This design is from a past posting Instructable which was very creative.
Image 2. Note the "catch draw" (Ace Hardware) which holds the bike bar tight.
The nubby material is to secure the bike bar tight when closed with the catch draw, the nubby material is from an old rubber tub mat my wife very cleverly suggested.
Image 3. Shows tee in closed position, use rivets if possible.

Step 3: Adjustable Heights

Image 1. Shows lower position, note extension on ground.
Image 2. shows extension used for higher position.
Lower height may not need lateral support, high position will require lateral support from a surface such as fence or wall.

Step 4: Bike Stand at High Position

The taller wood fence is 6' tall.
Note wire tie at fence post for laterial support.
Second image shows pedal rotation clears vertical pipe because of the 1.5" electric conduit 90 degree radius fitting.