Last year I ditched my 853 Inbred frame which, although a great ride, was giving me grief with chainsuck (it has very wide chainstays) and replaced it with an Pipedream 853 Sirius. For various reasons I didn’t ride much over the winter and having re-started recently I’m finding that I’m getting pain in the sit bones after an hour or two.

The ride position on the Sirius is great and it’s a nice fit, I’m using the same model saddle (ti-railed Bel-Air) as I was on the Inbred and a Thomson post (although this one’s layback instead of inline); saddle height and angle feels fine.

I may simply be out of practice and in need of hardening my behind up a bit; I suspect that I also have a slightly rosey memory of the Inbred and that any new bike will take a while to get right. The Sirius does have chunkier seatstays which may affect things but I’m not feeling remotely beaten up on the Sirius, even though I’ve switche d to a rigid steel fork (there’s no lower back pain for example), generally it’s a comfy ride, it’s just these nagging sit bone pains.

Is it just a case of persevering or is there anything I can try?

Drop your saddle 3mm.

Drop your saddle 2.8mm

nothing to do with seatstays.
i would guess your cockpit is shorter and/or higher, you are putting more weight on your arse and less on your hands and sitting more upright.

The cockpit is a smidgen shorter, so that might have something to do with it. I’d assumed that heavier guage seatstays might stiffen things up a bit but perhaps that’s not the case.

I’m in the same boat and asked pretty much the same question. My top tube is shorter and I feel slightly more hunched but the main problem was that my seat angle was well out

It’s a saddle, not a seat. You should not be sitting on it long enough for pressure sores to develop.

It’s a saddle, not a seat. You should not be sitting on it long enough for pressure sores to develop.

If he were a downhiller on an uplift day I’d agree. But based on the rigid forks I’m going to to guess he’s riding more normal XC type stuff which is going to involve a lot of sitting down, you’re only standing up on the downs (maybe 15-25% of a ride), and even then you’re probably resting between corners/rocky bits, so only stood up maybe 1/3 of that, so 5-7%. If you really are that rad that you don’t sit down take your seatpost out and try going for a ride, I snapped my seat collar once, after 10 miles I’d have sold my kindeys for just a seatpost let alone a saddle!

Back to the OP, the inbred has quite a steep seat angle IIRC, and you’ve gone from an inline post to a layback so I’d guess you’ve gone too far back, maybe try an inline post, and possibly a lighter, more springy, one than a Thompson.