I just tend to do lumpy rides with a small group of people that I absolutely know beyond a shadow of a doubt don't mind waiting for me, and who I trust absolutely to tell me if the ride is too hard or the group that is riding are looking for a faster-than-Crinkly-speed ride. Shared expectations and all that....
In fairness I gained this knowledge and this trust by taking a risk by going on a stupidly hilly ride up to the Lion Inn in the North York Moors with them back (first time I'd met nearly all of them!) in the summer of 2010, armed with a large amount of cake. And they walked up the hills with me (I suspect I walked more than I rode!) and waited at the top of all the hills for me, and sunbathed halfway down Little Fryupdale for absolutely ages whilst we dealt with the minor catastrophe of my front brake cable snapping part-way down the descent, and put up with my descending being a terror-fuelled squeaking-in-terror snail's pace almost slower than my climbing from that point onwards. People missed trains, and appointments, and were late home for their teas, and it was pretty much all my fault.
And then they invited me out again, so I thought they probably didn't completely hate me and went.
Then this summer we repeated the ride, and I only had to walk a few hundred yards up Kildale and one short stretch on Commondale and discovered that going down Little Fryupdale with two functioning brakes is simply glorious.
Sometimes the risks are worth taking and the gambles pay off
