Now that more than one wheel/tyre size can make the trails come alive, why don’t manufacturers do a replaceable dropout that extends down a bit fo B+ and is a bit higher for 29

EVen that 4 grand pivot with the optimiZed new hub standard etc has a bodge for the wheel swap (ie change the front but not the back)

Is it that hard to engineer these ? – feels to me like it’s be a cheapish addition to a spec sheet

Does it need to be in a different place? High tower seems to manage

well, I’m not really interested in “managing”.

If it’s really true that the optimal setup for a 650b+ frame is different (in the case of the Pivot) by exactly the amount that results from adding 20mm or whatever under the head tube (still an overall lowering of CoG I expect, and slacker head & seat angles, then fine

The hightower, on the other hand, claims to retain the same head angle (I think by raising the back end, which doesn’t make sense to me, geometrically), but if they have altered the rear link and kept the head angle the same, then seat angle and/or BB height will have changed

I struggle to see how that’s optimising anything – unless it really, really is and if so, how odd that optimising 2 fairly similar bikes is done by means that sound like they’re opposites. If you took BOTH solutions you could retain the same geometry with each wheel size by changing front and rear, which would seem sensible to me

(don’t get me wrong, I don’t really care – don’t own either bike or anything like so posh currently and I’m not a good enough rider that I’d miss half a degree here or there, but these are sold as cutting edge dual-“optimised” bikes … with what appears to be a bit of a bodge built in)

I remember when one bike, rigid, canti brakes and no choice of wheel size…..

Mrs_oab has odd converter dropouts on her trek. Solid, yes. A faff to unwind QR, yes. It’s still not an easy or elegant solution.

I could picture an easier solution, though not engineery enough to see how it would stand up to forces applied

I have a hardtail frame with dropouts that “swing” backwards to tension the chain – takes about 2 minutes to do and retighten. They could easily be set to hinge downwards instead, maybe with a spacer that slots into the gap when they extend downwards.

It seems a trivial fix – maybe it’s a trivial problem too, dunno. As said, maybe the small change in geometry actually IS optimal for the slightly altered wheels sizes/tyre pressures etc. If I was in marketing and my engineers told that was the case, I’d have it spelt out in my adverts. If it wasn’t the case, I’d be saying “why can’t we change it?”

anyhow, meh 🙂