When I was coming down from Genting Peras, at the kampong flats, me and wife also can do 25km/h to 27 km/h average and so did a few more on the Dahon MU P8, KHS F20 even the Kalaq, in addition to mine and wife's Dahon Eco C7. But the point is we know it's only another 10 km run till the coffee shop, but can we go further??? It's endurance also. How long can we last pedalling at high gear? We also need to pace ourselves, know the route well or find out about the route.
Reminds me of a story my friend told me. There was this jamboree trip and there was a thousand riders. As with Jamboree riders, MOST don't know the route and were never well prepared. So the ride started and my friend who knew the route well was starting slowly and his riding companion ask him to hurry. He said, " No worries, with the pace they started off, most won't finish". And he was right, only a small group lasted till the end. Just like the Penang round island ride, half way, most of them were on the municipal lorries. Still the best is riding constantly and increasing your speed as you get used to it. A good training is Putrajaya. In the beginning, I started with using the whole range of the 7 speed. Eco C7 is a 7 speed bike. Then after a few rides, i never used the largest 2 cog. Now, I don't shift at all, maintaining at 52T X 13T, eventhough I have 27 speed. It's never about the bike, it all your own's capability.
I will give a good tip for those who are not really into upgrades. Upgrading a front crank is expensive, we all know it. What you can do is , change the front crank to double, like 50/39 or better still 50/36, very ideal compromise. (can get second hand ones in BBS) Other than that, nothing else. If you ride mainly on flats, use the bigger crank and if on trips to Genting Sempah, Genting Peras or Fraser's Hill, manually shift the chain to the lower ring and used that for the whole trip.
Last week another rider kaki of mine bought a KHS F20. It was actually an 8 speeder but the shop has added a double crank to the bike making it 16 speed. He got it for 1.5K from GW cycle (give and take a little, depending on how good your bargaining power is ). It's light, much lighter than my Eco C7 and it's fast too. I hear there's another importer for KHS somewhere in Klang and some say it's cheaper than FB Bikes and GW. Check it out.