Can´t remember major issues with the mod when I tested it last time with Eduke32 R10459. It also looks great in polymost with it, so you may give it a try and see if the bike still flickers.
Worth noting that the bike does have a drivability issue where it can collide with walls (of some sort) while on slopes, even if that wall is on a ceiling.
Well, I used Polymost. May the issue depend on a certain setting, maybe? It's actually quite annoying. Does it require r_usenewshading 2? I was using 4, which is the default in recent EDuke32 builds.