Ozonation

I was biking home from a dinner meeting on my Brompton (about 12 years old, well used but still in good shape). I noticed that on the right shifter for the internal hub, it couldn't seem to find the middle gear suddenly (or perhaps it was the lowest gear that was giving problems). The left derailleur worked, but not the right it seemed. After a bit, I managed to fiddle the shifter, and shift the internal hub into the middle range. But by the end of my ride, I noticed there was a odd click - it almost sounded like the bottom bracket was rattling or something, and it almost felt like there was too much play in my pedaling. But when I shifted the hub into the highest gear, the noise and rattling would disappear, or at least be practically unnoticeable, and it seemed to pedal fine. As soon as I shifted back into the middle range on the hub, the feeling of looseness, clicking, etc. returned.

Given the timing - no problems to my meeting, only coming back - the only thing I can think of was that when I was about to leave, an acquaintance took an interest in my bike, and I let him ride it for a minute or so. I don't know if he tried shifting the internal hub while under load, as opposed to just shifting. Still, I've done that by accident a number of times, and it didn't cause any damage to the internal hub. Or maybe after 12 years of faithful service, something's just fine broken or needs major rehauling.

Any ideas?

bargainguy

I suspect that your internally geared hub cable has gotten a little slack or stretched.

When this happens, you can be slightly out of a gear but still retain forward pedal motion. It won't mesh well, though, like it's out of sync.

Typically, 3-speed internally geared hubs have a procedure to adjust cable tension when in the default gear.

On my SRAM 3x hub, for ex., I use the indicator chain to fine tune the middle gear so that the line in the chainbox window aligns with the two lines outside the window. Like an old-fashioned rangefinder.

tcs

I think barginguy has called it. High ("3rd") gear is selected with a cable slack condition. If your cable has slipped just a bit, it wouldn't affect high gear - more slack is still just slack.

tomtomtom123

I'm surprised you haven't had to adjust for cable slack for 12 years and so never considered this to be the cause of your clicking noise and pedal skipping.

It was the first thing I had to adjust on my SRAM dual drive on the bike out of the box, and then once every 1-2 years whenever I felt the internal gears not meshing correctly.

However the SRAM has a plastic housing for the shift box, so I imagine the calibration could misalign more quickly than the sturmey archer.