Nathan I have fitted NJB to 4 trials bikes they range from 88GBP to 128GBP. The Rock shocks are excellent but much more expensive. Falcons are also excellent but again expensive. The Betors are inexpensive but I have seen numerouse shocks fail regularly to the extent that my local twin shock club has a member who always carried seals etc to help out other members. The Sammy Miller ones are based on Betors although I beleive are aluminium bodied and have upgraded seal heads.
I have basic NJBs on my TY175 with the single tension springs and there top 'trik-shocks' fitted to my Cota 242 and have been very impressed with both. The best set up for a TY175 is to use longer shocks (by 25-30mm) than standard which increases rear ride hieght and then you can slide the fork tubes further through the triples to equal the rear increase. This improves ground clearance which is a little lacking on the 175. With standard length shocks the fork tubes shoulds extend 40mm through the triples.
The NJBs are not rebuildable but the manuafacturer will sell a bare shock (not spring or spring lands etc) as a replacement as he claims the cost difference is marginal and often shocks are bent in trials which is the cause of failure anyway.
