Cables for Brompton 3 speed gear leavers

[Brucey]

it may not seem like it when cables are first installed, and are moving easily, but in the longer term it is of advantage if the nipple is a snug fit in the shifter. The reason is that when the cable gets sticky, or the hub doesn't shift cleanly (so briefly stops pulling the cable) the nipple may come unseated inside the shifter during an upshift. Needless to say this is never an entirely good thing and indeed it may be a very bad (shifter breaking) thing.

If you go modifying the shifters so that they will accept a standard cable

a) 5mm is too big, even a standard cable nipple will be a slack fit in a hole that size and
b) if someone goes to fit the correct cable subsequently they will find that it won't fit properly and will be super slack.

And that is if you don't wreck the shifter in the process of using a drill on it. If you just drill the hole in the outside of the shifter a standard cable nipple won't be seated at all inside the shifter (there is a photo of this in the link below).

So I would always recommend that you modify the cable to fit the shifter not the shifter to fit the cable.

https://fernandoj.wordpress.com/tag/brompton-gear-cable/

The above link shows what is involved. You can file two flats on the nipple for some shifters but for others the nipple should be made cylindrical as per the correct Brompton part.

FWIW if you mount the cable in a short length of spare cable housing, and keep the cable under tension (eg using a spring and pinch bolt), you can bring the nipple to bear against a grindstone, grinding both the housing end and the nipple together if necessary. Because the assembly can be rotated, it is not difficult to keep it round and to make it the correct diameter this way.

cheers

[Philip Benstead]

Just spoke to Condor Cycles, they confirm that you should use Silicon Grease on the Brompton leaver. In fact you should use that on all places on plastic interfaces.

I just orders some of this, https://www.amazon.co.uk/PROUNOL-Silico ... vascript.1


let hope this is the correct one.

I believe Shimano uses Silicon grease in its twist grip leavers but it very expensive to buy,

https://www.chainreactioncycles.com/shi ... -prod33666

a bit cheaper

https://www.bikeparts.co.uk/products/sh ... 0sQAvD_BwE
unless somebody on here knows of cheap sources?

[fastpedaller]

I've struggled to find silicone grease at a reasonable price. Silicone spray can be reasonable though - I've not tried putting some in a pot and left it to see it any solvent evaporates and it becomes grease? - It could then be effectively pricey
The cheapest source (of what I think is silicone grease) I've stumbled across is sold as electrical contact grease.

[Brucey]

silicone grease is used to assemble plumbing fittings with. In my local tool store I was able to buy a 1lb tub of silicone grease for about £15. It is also available in aerosol form; a product of this type is recommended for Hope brake pistons too, so you can kill two birds with one stone this way.

cheers

[Philip Benstead]

Silicone Grease
Cheaper but look at postage

https://www.google.com/search?q=Shimano ... 3947282906

[Philip Benstead]

Should we be using one of these for our cables?

https://www.ebay.co.uk/itm/Oxford-Motor ... 0677.m4598

But how?

[Brucey]

I own and use a hydraulic cable oiler





Actually mine is the standard (not heavy duty) version;

this allows easy (but slightly messy) cable lubrication provided the cable end fittings can be released from the lever. This is easy enough with flat bar brake levers, not so easy with gear cables or cables in dropped bar brake levers. It is especially useful for hub brake cables; for example SA hub brake cables which have a nipple both ends and cannot be disassembled.

The hydraulic action forces lube into the cable at high pressure if necessary; this is far more effective than using an aerosol; using the hydraulic oiler lube can be forced into cables of any length. If you use an aerosol it is questionable if the pressure is high enough, and how quickly the solvent in the lube evaporates. If you want to lube cables using an aerosol, you can fit inline oilers quite cheaply and this is a good approach since it introduces the lube in the middle of the cable rather than one end only, which makes up for the lower pressure.

cheers

[Philip Benstead]

Looks interresting

https://www.youtube.com/watch?v=aQnMdOL09uY

[Philip Benstead]

This may of interest in terms of how to service the gear levers on newer Bromptons. I reckon you can use a Shimano cable on both levers if you drill a 5mm hole for the cable insertion point.

https://www.youtube.com/watch?v=EwYEYO3h2Po

Looking at the you tube film it says the bolt should be tighten to less than 1.0nm where can you obtain a torque wrench that can be set to such a low setting?

[PRL]

Thanks
I have an old Sachs hub that was playing up so I thought I would replace with modern SA and change the trigger and cable at the same time.
Wheel and trigger fine. The adjuster I had to get on e-bay.
Thought I could transfer the sprockets but they have changed the fitting.
Getting the right length of gear cable looks to be trickier.
Cutting generic cable to matching size looks simplest and I will take your advice to file down the nipple.