Originally Posted by
prathmann
The folder that I mentioned above (451 - 20" wheels) does have a 60t chainring and an 11t small cog which gives it a maximum of 109 GI which happens to be the same as my other road bike (622 - 700c wheels) with its 52t chainring and 13t small cog. But frankly the gearing is not what limits my speed on either bike except for a few downhill stretches or with a terrific tailwind.
It's easy to increase the highest gearing - the Schlumpf 'highspeed drive' BB will multiply the GIs by 2.5 and there are plenty of internal hub gears that can provide just about any range of gears you may want. The limiting factor is whether you have an appropriate engine to drive such high gears.
Of course the engine is the limiting factor once you've got equivalent gearing, but the fact is most stock folders will have not only lower max GI, but lower GI throughout the range, than will a typical road 700c setup.
My point is merely that folders are not any slower than 700Cs of necessity; if they're setup right, geared right, or the rider can spin like a pro sprinter, they're just as fast. They are slower in practice, generally, because they are not geared for speed, nor set up for aero efficiency.
Sure, you can get yourself a 73t, or a Schlumpf BB, but you have to be aware of the issues first.