I found this on forum about Regina. There are other good chains EK , RK , DID Tsubaki . There are also many other brands , the point is buy the strongest chain you can afford . Please read below :
Most say good 520 chains these days will not snap, most sell DID and say they are good with few probs and are happy to fit… but the Regina O or X ring chains are consistently the best by reputation, and the X-rings out last 2 sets of sprockets and the even the bikes they are fitted to. OK so far sounds great…
An american magazine test found that the claimed breaking strain on all chains were easily 100% exaggerated some OM replacement chains were 1/4 the strength they claim. But RK DID and Regina were the best for strait breaking strain. They jet washed all 13 chains and found that only the Regina X ring chains kept their lube in after 4 mins jet wash, hence I guess their super long life reports.
A friend who was a KTM enduro works “spanner monkey” said that they would use non ringed chains for most races as the ringed ones are a little stiffer especially for the first 200km and it saps some horse power that the works bikes have worked hard to get, so money no object they they would change them every race. He was sponsored by RK, but they sold those chains to unsponsored racers if they were doing long events and bought and fitted Regina instead as they only needed adjustment once after fitting, other makes would stretch too much under race conditions leading to some adjustments mid race that are a problem you do not need when on the clock.
Regina 525 ZRP Series Chains are original equipment on Aprilia RSV4, BMW S1000RR, Ducati Panigale 1199, KTM RC8 and many others (and Norton !) . Z-ring chains feature the patented Z44 sealing rings, which greatly improve performance and wear life.
