I want to replace a rim on my commuter. It’s a Stans Crest 29er with an ERD of 605.

How close does the ERD of the new rim need to be for me to still be able to use the existing spokes?

For example, a Velocity A23 rim is 601 – would that be okay?

4mm is quite a lot – you *may* get away with switchign to 12mm nipples if you currently have 14’s fitted but I think you may find nipples bottoming out on the spoke threads if you keep spokes and nipples.

Ta. Is 605 the diameter of the ‘wheel’ then, in mm?

So a 601ERD needs spokes that are 2mm shorter than a 605ERD (basically)?

Yes 2mm difference in spoke length between the rims
I would reuse your spokes should be ok

cheers

Ta. Is 605 the diameter of the ‘wheel’ then, in mm?

as ERD = Effective Rim Diameter, yes.

Some maufacturers use a different standard, IIRC Mavic’s ERD are ~3mm out compared to other companies way of measuring.

from http://www.bikeforest.com/CAD/wheelCAD.html

Mavic supplies the spoke support diameter of all of their rims at there website: http://www.mavic.com. The Bicycle Forest has added 3mm to these values to arrive at the effective rim diameter.

would this work the other way??? say going from an erd of 530 to 533

say going from an erd of 530 to 533

prob not as only 1.5mm difference but check & see if you can tell how far into your nipples the spokes already run – right into the head & you will be good to go no problem