Gearchange problem - bottom bracket shield?

[Fastpedaller]

Yesterday (despite cleaning the bike recently), the muddy Norfolk roads did their worst - When I changed to a higher gear it didn't happen until further shifter movement, which then put me in an even higher gear than I wanted! Time for maintenance, and a clean of the cable guide on the underside of the bottom bracket, followed by a little silicone grease had it all working again. It made me wonder about making a 'shield' to fit over the guide and could be clamped in place between the BB and the cable guide, with an access hole for the allen key to hold everything in place and act as a drain hole for any water that enters. An issue would be the difficulty of inserting the cables, unless this is done before the cover is added, or a clip-on cover. Any creative 3D printer users on here?

 

[Sharky]

You could try with a short section of cable outer.

 

[Shearwater Missile]

Yesterday (despite cleaning the bike recently), the muddy Norfolk roads did their worst - When I changed to a higher gear it didn't happen until further shifter movement, which then put me in an even higher gear than I wanted! Time for maintenance, and a clean of the cable guide on the underside of the bottom bracket, followed by a little silicone grease had it all working again. It made me wonder about making a 'shield' to fit over the guide and could be clamped in place between the BB and the cable guide, with an access hole for the allen key to hold everything in place and act as a drain hole for any water that enters. An issue would be the difficulty of inserting the cables, unless this is done before the cover is added, or a clip-on cover. Any creative 3D printer users on here?

I had thought about that too and tried it, attaching a piece of plastic over the cables. I attached it via the bolt that holds the btm bracket guide in place. It was kind of all right but crud still went underneath it. In the ideal world the cables under the btm bracket would still be in their outers. Anyway, I ditched my effort, but check and clean the guides more frequently.

 

[MichaelW2]

Cable outers gather water unless the run the whole way.

 

[Ajax Bay]

Frankly you're better off keeping the arrangement as designed. Any kind of 'shield' would function as a crud gatherer, potentially generate crud friction, and deter a simple clean and with it any early detection of a strand of the cable parted.
Include as frequent maintenance a simple clean and a quick wipe with a GT85 paper towel followed by application of grease to both cable 'channels'.
Ride on.

 

[Ian H]

A longish flap on the front mudguard would keep it clean. Assuming you have mudguards.

 

[Fastpedaller]

I had another look at the bike and realised there are 2 screws for mounting a bottle cage near the BB, on the underside of the down tube (it's a Spa Tourer frame). I've never used them, but the rearmost one could be utilised to fit a small aluminium or plastic deflector. Ian H mentioned mudguards - I do have mudguards (Tortec), and the front one could possibly be extended.

 

[Ajax Bay]

I respectfully suggest (from muddy East Devon with an externally cabled frame) that you're overthinking this and and not keeping your bottom (bracket shell) wiped.

 

[C R]

Is it just me that glancing at the thread title reads gearache?

 

[EckyH]

Cable outers gather water unless the run the whole way.

There's a solution between the "naked" cable and "housing the whole way" at least from Jagwire - the Elite Sealed Shift Kit.

That works really well on my bikes. I can recommend it.

E.

 

[C R]

There's a solution between the "naked" cable and "housing the whole way" at least from Jagwire - the Elite Sealed Shift Kit.

That works really well on my bikes. I can recommend it.

E.

But isn't continuous liner (that's the description in the link) the same as housing the whole way?

 

[EckyH]

But isn't continuous liner (that's the description in the link) the same as housing the whole way?

It depends, I think - how we define "housing".
In my terminology housing means the outer part which routes the cable around curves and can take the resulting forces caused by the cable tension.

But I'm married to my wife, not to that definition.

E.

 

[C R]

It depends, I think - how we define "housing".
In my terminology housing means the outer part which routes the cable around curves and can take the resulting forces caused by the cable tension.

But I'm married to my wife, not to that definition.

E.

So the jagwire thing is not a full outer all the way? I'm curious about how it looks when installed.

Edited to add. I've looked it up via a search engine and found a review in road.cc. Instead of a full outer all the way it extends the inner liner between outer stops, so the inner is not exposed anywhere. The link is here for the gory details
https://road.cc/content/review/215523-jagwire-road-elite-sealed-shift-kit

 

[Dogtrousers]

Why do we have exposed cables anyway?

I'm pretty sure that cheaper bikes bitd used to have full length housing. They used to have metal clips that clipped the housing to the frame. But better bikes had exposed cables with little guides under (or some over, which went out of fashion) the bottom bracket. There were (and are) stops so you could have an exposed run of brake cable along the top tube.

But why? Is it to save the weight of all that cable housing? Is it because all that length of housing is prone to compression, so you keep the housed runs short to limit the squashiness?

 

[EckyH]

So the jagwire thing is not a full outer all the way?

Exactly.

So the jagwire thing is not a full outer all the way? I'm curious about how it looks when installed.

Like so:

The translucent white thing is the liner.

But why? Is it to save the weight of all that cable housing? Is it because all that length of housing is prone to compression, so you keep the housed runs short to limit the squashiness?

In my opinon reduction of friction in the whole way was the main reason, followed by reduced compression. Compressionless housings, in particular for brakes and with low friction liners inside, aren't that old.

E.