Brompton shifter (3-speed)

[Pickled Onion]

I am new to the delights of a three-speed Brompton, the shifter seems incredibly stiff when shifting to higher gears.

(a) is it supposed to be like that?
(b) can I do anything to make it work properly?

[Arellcat]

Are you trying to change gear while applying force to the pedals?  Sturmey 3-speeds don't generally like that very much.  If it's still incredibly stiff to operate even if the bike is on the workstand, you might try disconnecting the cable from the indicator rod (via the tiny chain that disappears inside the axle) and see if the gear lever is still stiff to move.  It should be notchy but otherwise fairly loose.

[yoav]

I had a similar problem and it turned out not to be the shifter but the cable - the outer had worn and was catching the inner where the cable passes behind the chainset so wasn't too easy to spot.

[Jacomus]

In addition to what Arellcat says about being careful not to shift under load, I've also found that the shifter going very stiff/notchy is an indication that the timing chain tension has slipped and needs to be fettled.

[Kim]

The reluctance (read: outright refusal) of Sturmey hubs to shift under load came as something as a shock to me, having previously only ridden dérailleurs and the occasional Shimano hub gear.  Until you get a feel for it, you pretty much have to stop pedalling - simply easing off as you would when changing down on a modern dérailleur system isn't enough.  Static force is a problem too - it'll be just as reluctant to shift if you're holding the pedal against a brake or the weight of the bike uphill.

I defer to the others on the specifics of the 3-speed hub, but will make the general observation that Bromptons are a fairly harsh environment for cables, and if the indicator chain thingumy is correctly adjusted, the cable (especially if it's old or of unknown providence) would be next on my list of things to check.

The Brompton shifters have a reputation for being pleasingly reliable, in spite of their plasticy appearance.

[rogerzilla]

Some of the older ones actually needed a bit of load to drop firmly into gear but the current crop are best shifted when freewheeling.  Basically the clutch won't slide along the axle if it's transmitting torque, because that wedges it in position.

if you replace the cables, buy a roll of outer cable and measure the existing ones very carefully before you cut the new cable to length.  The length is carefully worked out to allow folding but to gather the cables neatly together when riding.  it looks cack if one is a centimetre too long.

[Kim]

+1 to that.  Having worked out the length of Brompton cables by trial-and-error^[1] for a custom handlebar arrangement, I can say that you've got to be within at most a centimetre of the correct length for the fold to work properly, and within a couple of millimetres relative to the other cables for them to gather neatly^[2], unless you force the issue with cable ties (which brings its own issues, but is tempting to make things look neat when there's electrical wiring in the mix requiring some cable ties anyway).

There's a thread somewhere where people were collecting the official lengths of the various cables....  Ah, found it: https://yacf.co.uk/forum/index.php?topic=23131.0


_{[1] Good thing I already had a 200m roll of brake outer...
[2] Meddling with the positions of the shifters/levers will have the same effect.}

[rogerzilla]

I's probably also worth rubbing the inners with grease and only buying stainless steel ones.  I know we were supposed to have left all that behind with low friction plastic coated liners but this is about survival, not about perfect Hyperglide performance.  The common SA hubs are fairly unfussy about exact adjustment anyway; as long as the cable has no tension left in top gear and there is barely any indicator chain able to be pulled out of the hub in low gear, job's a good 'un.  None of this 11-speed stuff with miniscule spacing.

[Pickled Onion]

Thanks for all the replies. The problem was when shifting up to a higher gear, ie letting the cable out, which intuitively should be possible even under load because the cable will just go slack until the load is reduced and the hub can take up the slack and shift. Also it was still stiff when freewheeling. All new kit.

Anyway, the answer was simply the adjustment being too tight. What was happening is the cable was in too high a tension in each gear which was tugging on the ratchet in the shifter and holding it tight - what confused me was the fact this was also the case in middle gear. It turns out the SA hubs are not as tolerant of adjustment as I'd assumed, it is now visibly slack in top gear and works smoothly.

On the subject of cables, the ones supplied by brompton are massively better than they used to be. With four folds a day and riding through the winter the ones from ~10 years ago used to break apart after around a year. The recent ones last much longer, so now I'm happy paying a few quid extra for the brompton supplied ones instead of cutting my own.

[Jacomus]

Nice one, PO

[Biggsy]

I even back-pedal a bit when changing hub gears - an old habit from riding ancient 3-speeds.  Shouldn't be necessary with a well-adjusted SA in good condition, but still it ensures the gear properly engages.