Hope this hasn't already been covered, if it has can someone point me to the right thread...

Looking to get some Rental Fat Bars off adventure spec to go along with my existing 20mm risers..will this pose a problem re. existing cable lengths?

Secondly, not quite sure/bit confused by the specs of the fat bar and wondering if I have to get the 'wirtz adapter':

Off the Adventure spec website:

(If your bike has non-tapered 7/8th inch diameter bars as standard you can use the Wirtz adapter in 'Related Products' to fit the Fatbar)

Many thanks.
Tom