How much is TOO much?

OK, hope this makes sense...

I'm getting back into tri training but am only a few weeks in again. Lost a few lbs and taking it very easy with short easy runs, swims and a few bike rides. So, my next door neighbour is a pretty keen cyclist and pretty fit on the bike. He asked me if I wanted to ride with him and today I joined him for a ride. He told me his route was 20 miles and said he'd wait for me etc if I was slow. We headed out and it turned out to be a 28 mile route - about 12 miles more than the 16 mile easy rides I have done so far. It was a fairly undulating ride with plenty of short hills to get the pulse up but lots of easy bits to allow me recovery time. I rode my own pace, got dropped on every hill and he waited for me each time to catch up, as promised. It was a 2hr ride that I really enjoyed and certainly gave me a HARD workout - a lot harder than any rides I have done so far. It was the first time I ever rode with a partner and I really enjoyed it as well as it motivating me.

My question is, would I be stupid to jump up to this length of ride as my weekly long ride so soon? I feel well worked out but not crippled or anything. I'm conscious of not over-training but equally I never felt I pushed myself enough on the bike when I used to train before.

Any advice is welcomed.

Edited by Bigpikle 2009-09-20 10:58 AM