Replacement rubber twistgrip bits?

[LittleWheelsandBig]

A friend in Oz has 3x8 and 3x9 SRAM Dualdrive separate twistgrip shifters on his recumbent trikes. The shifters themselves are fine but the rubber covers have worn and enlarged, so they tend to slip relative to the shifter mechanism. Does any retailer have replacement rubber bits for these shifters?

Failing that, are the complete twistgrip shifters available? I know that SRAM has abandoned their F&S heritage.

[drossall]

I've just bought a new 7-speed twist grip unit from Evans. A quick Google suggests lots on eBay.

[Torslanda]

Just scoured the ZyroFisher website for SRAM shifter spares. They only seem to list the current XO/XX grips. Dual drive spares are limited to hub stuff only. FWIW St John Street appear to have uploaded the Zyro catalogue.

If you can find replacement shifters buy them.

[LittleWheelsandBig]

Thanks Torslanda

I think the front derailleur twistshifters are incompatible with DualDrive cable pull. Can anybody confirm this?

I expect that the rear derailleur twistshifters are interchangeable but I get confused with the whole 1:1 pull ratio versus Shimano-compatible thing with regards to DualDrive derailleurs. Where can I find an idiot's guide to compatibilities?

[LittleWheelsandBig]

My best guess is that the SRAM X series twist shifters (1:1 actuation or have I got that the wrong way round and should we use Shimano-compatible 2:1 actuation?) with the appropriate number of clicks (8 and 9 in this case) are interchangeable with the existing Dual Drive rear derailleur but that the Dual Drive hub twist shifter is virtually unique in the known universe.
https://www.sheldonbrown.com/cribsheet-IG-cable-pull.html

Assuming I fail to find replacement separate left and right Dual Drive twist shifters (which is looking likely), are trigger shifters an option on underbar recumbents or is cable routing impossibly difficult?

[Kim]

Assuming I fail to find replacement separate left and right Dual Drive twist shifters (which is looking likely), are trigger shifters an option on underbar recumbents or is cable routing impossibly difficult?

You can make it work, but I've never seen an arrangement I liked.

The logical ergonomic arrangement leaves you with the cable exiting upwards and needing to do a 180-degree turn.  I've seen it done with suboptimally tight loops of outer, and with flexible v-brake noodles.  They were both nasty.  You might be able to hide the worst of the fugliness/snaggability if there's a mirror sticking out of the bar end.

Or you put the shifter at the bottom of the grip with the cable exiting downwards and take your hand off the bar to pull the triggers.  Much neater, but inelegant.

[LittleWheelsandBig]

That was what I figured. Maybe I can source some NOS twist shifters at ridiculous prices but I've not found them yet.

[Brucey]

you can often 'refresh' the extant worn rubber bits by adding material to them; for example lengths of inner tube can be bonded to the extant grip, or just slipped over the main section. This can be repeated ad infinitum.

Re the 3s control cable pulls, it isn't the work of genius to convert the hub to a pull chain (like wot they used to be..... ) instead of the crappy pushrod arrangement (I have done this by removing a spring and using modified SA parts) and then you have a hub that will work with all kinds of 3s shifters.  IIRC the key things are that gear 2 is correct and the cable goes full slack in gear 3 (high gear). IRRC it doesn't matter so much if the cable pull is a bit short to gear 1; provided it runs it runs. When converting the hub you will see how far the clutch actually needs to move to make the shifts.

 If the cable run is long and/or convoluted then it isn't a bad idea to fit a cable assist spring externally because the spring in the hub may not be strong enough by itself, but this is not always required and it is  is no big deal if it is.

Regarding the controls on underbars; if there is enough space you can sometimes fit a bar-end shifter; if there is room then this is both ergonomically satisfactory (asides from the odd prod in the thigh when getting on and off the machine in some cases) and good from a cable routing POV . You can of course shorten the bars slightly to make more room in some cases.  If you use a shimano mech and (say) 9s you can use a sun race bar end shifter for the rear mech and a Sunrace (sturmey archer)3s bar end control for the LH side. They are identical-looking apart from the branding IIRC.

cheers

[LittleWheelsandBig]

There are a few complicating factors.

Animal already has bar end shifters for the front mechs on his trikes, so I am loath to go that route for controlling the hub.

Modifying the Dual Drive hubs will be difficult, seeing as they are in Australia (far away from experienced hub gear hackers).

The twist shift covers are not just wearing thin, they are enlarging and slipping round the mechanism.

[Brucey]

There are a few complicating factors.

Animal already has bar end shifters for the front mechs on his trikes, so I am loath to go that route for controlling the hub.

Modifying the Dual Drive hubs will be difficult, seeing as they are in Australia (far away from experienced hub gear hackers).

The twist shift covers are not just wearing thin, they are enlarging and slipping round the mechanism.

It may be possible to fit a thumbshifter right next to a bar end shifter and have it all work OK. Might need a bit of thought that one. BTW if you can mark the controls so that the middle gear position can be seen, you can use a conventional LH thumbshifter to control most 3s hubs.

The internal modification isn't difficult to do but then it isn't necessary if you use a friction control, either.

Inner tube of the correct size can  be a tight fit on the extant rubber parts; several layers can pull a loose rubber down until it is snug again. Tape wound tight beneath the inner tube can help as well.  Costs little to have a go, so why not....?

cheers

[Kim]

It may be possible to fit a thumbshifter right next to a bar end shifter and have it all work OK. Might need a bit of thought that one.

I have a thumbshifter controlling a parking brake^[1] on my USS Streetmachine (which has bar-end shifters for the gears).  It's mounted on the horizontal part of the bar, just before the upward bend.  Angle carefully chosen so I can operate it fully, but it doesn't foul the underside of the seat.


_{[1] More useful than it might sound - as well as stabilising the bike when parked / on trains, it means I can have both hands free while sitting astride the bike on not-perfectly-flat ground.  Great for quick photo stops etc.  It also means I've got an emergency backup friction shifter I can re-purpose if a minor crash destroys one of the bar-ends mid-tour.}

[mrcharly-YHT]

sugru?

[LittleWheelsandBig]

It looks like one of the suggested bodges might have to be the way to solve this. If only useful kit wasn't needlessly deleted...

[LittleWheelsandBig]

I think I've found a couple of NOS hub twistshifters for sale but won't be able to purchase them for a few days yet. It is a nicer solution than bodging IMHO.

Edit: bought and sent to me but I won't be able to get them to Animal until I return to Auld Blighty.