OK.



Never heard of anyone having trouble with that. But I can't see how that's "back pain" or even how one would be able to distinguish the exact source of internal pelvic pain like that. I know about referred pain, but if your doctor has diagnosed referred pain from the SI joint then they must have some idea about treatment.

But if that's really the source of your pain, and where you feel it, it must be just from the jarring of a bike ridden on the road. In which case, a suspension seatpost. The BodyFloat has very good reviews from users. Kinekt-BodyFloat Seatpost by Cirrus Cycles | Suspension seat post

It can be adjusted to eliminate bounce, unlike Thudbusters. I ride with a few folks who use suspension posts.

Bar height would have nothing to do with it.