Hi - glad to hear your tumour was so small, so hopefully the overall outlook is very good (but INSIST on regular scans to check for recurrance - don't let them tell you 'we got it all' - that's the primary, not any potential secondaries/mets that MAY be lurking in the bloodstream - RCC can recur even years and years later, I believe the record is something like 20 years, so don't let your guard down)(having said that, the smaller the primary, the less likely recurrance is)
Generally, the post-op exercise advice is walking (and walking and walking and walking!), but like you my husband also was on the bike fairly quickly, and after six weeks was tenatively back at the gym. Abs do stay 'weak' and he hated the 'bulge' around the wound, but it definitely healed very well (he got some 'skin tingling' because the nerves had been cut), and he was working out pretty 'normally' within a couple of months, as I recall. He was fit enough to go windsurfing two and a half months after surgery (though to be fair he was on steroids for his brain mets by then, and their initial effect is to make you feel strong!).
All the very best to you. Julie.