So expecting a bike with a 29″ Domain and want to convert to a Zeb ultimate

I have a set of 27.5 Zeb ultimates with a spring conversion (Vorsprung)
My understanding is the lowers are the same for Zeb/Domain (excluding stickers)
The 29 lowers just have the axle in a different position …

So basically should I be able to remove the 27.5 Zeb uppers and simply stick them in the 29 Domain lowers and have a Zeb Ult 29er?

Equally I understand the uppers just have thicker stanchions but the charger damper is transferable but not the air shaft so the other way seems to be move the charger 2.1 across and hopefully the spring will fit in the domain stanchions?

On the other rockshox products, the same air spring gives a 20mm difference in the 29er version. ie a 140mm airspring in a 650b pike would give 120mm travel in a 29er.
So I’m not sure if this means the uppers are somehow different by 20mm? or what travel you would get out of your frankenfork.

Also forks come in different offsets, at least some of the offset comes from the crown on the uppers – so I’m not sure if they will be the same between the wheelsizes or not.

On the other rockshox products, the same air spring gives a 20mm difference in the 29er version. ie a 140mm airspring in a 650b pike would give 120mm travel in a 29er.

Yeah this seems to be Zeb (and by inference) Domain specific.
(Perhaps with the exception of the A1 Lyrik which was just weird)

Im basing this on “How to turn a RockShox Zeb from 27.5 to 29 | Butter Suspension”

but assuming that to be the case then the insides of the lowers are the same so travel will be the same.
If I did need an extra 20mm (don’t think that’s the most likely issue based on video) I just set the vorsprung spring to 190 to give me 170…

Also forks come in different offsets, at least some of the offset comes from the crown on the uppers – so I’m not sure if they will be the same between the wheelsizes or not.

Yeah …. I’m assuming the short/long is crossed over but good point???
My 27.5 are 38mm and the 29ers are all ALL 44mm

If that doesn’t work I’m down to seeing if the spring from Vorsprug will go into the Domain

Maybe drop Vorsprung a line asking if they think it’s a go-er?

They may be able to confirm/deny the cross-compatibility.

I have a vague memory of the travel lengths changing to be the same across wheel sizes with RS, for air shafts at least?

ayjaydoubleyou
Full Member

On the other rockshox products, the same air spring gives a 20mm difference in the 29er version. ie a 140mm airspring in a 650b pike would give 120mm travel in a 29er.

I think this changed- always used to be the case but last time I needed an airshaft (for a pike I think) it was the same length for all wheel; sizes

The offset is all in the crown. You will be fine just swapping the lowers.

chakaping

Maybe drop Vorsprung a line asking if they think it’s a go-er?

Yeah did that yesterday so I’ll wait for Steve to reply…

I have a vague memory of the travel lengths changing to be the same across wheel sizes with RS, for air shafts at least?

Yep the Zeb only has a single airshaft/travel… not the usual 160/140 (or even older with 26″ 3 travels per size)

They may be able to confirm/deny the cross-compatibility.

They seem pretty good at not saying you are going to die tbf…

RickDraper

The offset is all in the crown. You will be fine just swapping the lowers.

That would be good… at least I’ll have slightly twitchier forks but I can probably live with that.

Sticking the domain on the heavier (e)bike though is probably most sensible if I can just swap internals..

The spring is the same size as the 35mm so 38/Zeb get a liner… I’m hoping that means the spring will just fit the domain CSU.