An odd problem with wheel/sprocket switching

[12boy]

I have an SRF 3 rear wheel and the one speed wheel that was on the Brompton when I bought it. Having been using the 3 speed in the winter, I wanted to go back to the one speed, which I can use as a 2 speed or a 3 speed since I have the sprockets for either of those. Working first with the 2 speed (12 /17 sprockets) I could not get it to work without skipping, even when in the 1 speed configuration. I tried different chains but nothing worked.
The free wheel on the 1 speed hub is pretty ingenious as its is very easy to get to remove the splined part upon which the sprocket(s) go. When off, the free wheel pawls are visible. In my case, the pawls and the notches into which they fit to engage the hub were gummy with old grease.Cleaning that old gummy grease from the pawls and notches resolved the skipping problem immediately. if that had occurred to me in the beginning I could have spared myself a lot of hassle. If your single speed hub skips and you think your sprocket and chain are working together ok, you might check the pawls.

 

[12boy]

Some time ago bikegang gave me a 3 speed sprocket set up for my Brompton. It is a 1 piece unit that requires removing the spoke guard, sticking on the one piece 3 sprocket unit and securing it with a thin circlip. Easy peasy. The unit has eleven, fourteen and seventeen tooth sprockets for a nice little range. In concert with my 58 and 38 tooth chainrings my range is about 36 to 85 gear inches and it's much lighter than the SA 177% 3 speed. Works very well, although when the 11 tooth sprocket goes the whole thing must be replaced. It requires a 10 speed chain, too.