Internal Cable Routing - Rear Derailleur

[BMWBen]

My missus has recently got hold of a nice second hand frame with internal cable routing that needs setting up.

It previous had SRAM eTap on it, and it needs to be converted to mechanical. She's got hold of the frame manufacturer and is chasing them for the external/internal cable guide/hole cover things which terminate the cable outer when the cable runs into the frame (it came with blanks due to the eTap situation).

The question is... how does the rear gear cable routing work around the bottom bracket? There's a little cover down there which you can take off, but I was expecting to find some little cable guide like you do for external cabling which would provide a stable path for the cable to turn the corner and head down the chainstay to the RD, but there's nothing in there.

Any ideas how it's supposed to work? Should there be a different cover that has the cable guide built into it or something? Is the RD cable supposed to have an outer cable run right the way through the frame or something?

[Matt_N]

Probably help to know what the frame is as some will differ.

You usually have an eternal cable guide on the B.B. shell, so the cable will be internal in the down tube then exit over the cable guide then go back into the chain stay. Or like you say there is an internal guide.

How old is the frame, can sometimes be hard to get the wired cable stops from manufacturers of the frame is out of production for example.

[BMWBen]

It's a Ribble 883 Aero (team edition - looks smart!)

There's an exit point for the FD cable, but now I think about it, no guide for that either. There's no out/in system around the outside of the BB area...

Never had a bike with mechanical internal routing so at a bit of a loss!

[lufbramatt]

Could you run a full length outer? Then no need for cable stops. Slightly more drag but works OK on mountain bikes. Should work for the rear mech, probably not for the front though.

[BMWBen]

lufbramatt said:

Could you run a full length outer? Then no need for cable stops. Slightly more drag but works OK on mountain bikes. Should work for the rear mech, probably not for the front though.

Yeah that's on the list of options... Like you say however, it doesn't solve the front. Current top option is to buy the same kind of bottom bracket guide you normally find fixed externally and work out how to attach it to the BB shell inside the small hatch at the bottom of the frame.

[louiebaby]

Would it not run something like this?

[BMWBen]

louiebaby said:

Would it not run something like this?
/Snip for photo

Interesting - cable outer all the way on that one it seems. Only one cable though - is that an MTB with a 1x?

[louiebaby]

BMWBen said:

louiebaby said:

Would it not run something like this?
/Snip for photo

Interesting - cable outer all the way on that one it seems. Only one cable though - is that an MTB with a 1x?

No idea, I was just looking for an example where the cable runs round the bottom of the BB shell. I think it's on a CX bike in that pic.

[millen]

Why not ask Ribble? Even if the cable guide was unique to that model and it's no longer stocked, they may have one from another model that can be trimmed to fit? Ditto the end stops.

My Planet X uses the system Matt_N describes. The fun part is threading the outer brake cable above the BB shell (mechanical discs)! Absolutely my least favorite maintenance job.

[lufbramatt]

Aren't Ribble "open mould" frames? So there may be other brands bikes that are essentially the same, and use the same parts.

[keith2.2]

Speculating because I'm not familiar with the frame, but on my Felt AR, there were two bb shell plugs. One is an enclosed one for running di2, the other acts as a cable guide for FD, RD and rear brake (so you have about 2 inches of cable exposed under the BB shell, iyswim)

[BMWBen]

lufbramatt said:

Aren't Ribble "open mould" frames? So there may be other brands bikes that are essentially the same, and use the same parts.

This is what has provided the answer - different frame from the same manufacturer (I think), the 872, has got some stuff on various forums about the cabling.

It seems that what you do is get a bit of PFTE sleeving and the cables literally just run free under the bottom bracket through it. So there is no internal cable guide, and the straight line path + cable tension between cable in/cable out points is all that keeps things in place.

If it works it works I guess! I assume you have to replace the PFTE sleeving stuff whenever it wears out. Seems a bit odd, but given that this stuff is easily sourced I guess quite a few bikes use this method.

[GOATever]

You could drill a suitable sized hole in the frame at the BB, insert a riv nut, and buy an external cable guide, then screw the cable guide into place, anchored by the riv nut. Remember to run the cables down the tube before you secure the cable guide. Use a length of outer to guide the cables down the insides of the tube, and out of the frame at the BB, then retract the outer.

Edited by GOATever on Friday 30th August 16:14