For the S76 (the only retractable I've flown) the maximum gear extended speed is 130 kts, while Vne is 155 kts. Vne is rather easily reached in level flight (in fact it's the first limit this time of year), so it's certain that the maximum gear extended speed can be exceeded.
The gear on helicopters doesn't have to cope with speeds much above that of fixed-wing, because they can't go that fast in any case.