Help changing an internal (infernal?) rear gear cable

in Workshop
As per the title. This is one of the few jobs I leave to the lbs but that doesn't seem to be an option atm. I think the last time they did this they threaded a gear cable outer through it and then put the cable through. I guess I wasn't paying too much attention as when I've tried this myself I've realised the cable port on the down tube is far too small for this. It looks like it can be taken out and I've removed the small bolt that holds it in, but it's flush to the frame and doesn't seem to want to budge. Any ideas on how to get this out?
Thanks in advance for any help.
B
Thanks in advance for any help.
B
0
Posts
You should be able to remove the cable port. It may have some sort of springy plastic piece to hold it in place. You will just have to explore carefully and use a small screwdriver/pliers to remove it.
Then drill or dremel a hole in the base of this big enough to allow the outer through. Then get some lagging. Wiggle and others sell it. It is foam type stuff that will go into the frame and stop the outer bashing the frame and driving you nuts!
Then look at the rear. The stop on the chain stay may also be removable. Mine was held on with 2mm Allen boltsThat all depends how the rear is threaded. Take care not to loose them! Drill/dremel this as well.
How does the inner exit the frame under the chain stay? There may be another grommet type thing that will also need drilling out.
Then run the outer all the way to the mech. Job done.
Not a difficult job to do....once you've got your head round it.
After I had struggled and finished I realised how I should have done it.
1) cut off the old inner at the derailleur
2) pull it out of the chainstay
3) remove both cable ports on the downtube - yes you will have to be able to do this
4) push some outer over the old inner up the downtube out of the top cable port
5) remove and replace the inner and feed it down the outer in the downtube
6) pull the outer from the downtube and feed the new inner down the chainstay
Yes, it's expensive, but the amount of time I've saved doing internal cable routing with it makes it worth its weight in gold.
If this is the only time you're ever likely to do it, get a strong magnet (this is one of the parts of the kit). It will attract the gear cable through the frame and allow you to guide it to the exit hole.
I'm wondering if this might partly be because the outer isn't running smoothly over the existing inner, but simply bending it? The solution would be to take the existing cable out (which is how the mechanic had to do it as I'd already removed the existing cable that time). But I'm nervous that then leaves me having to deal with magnets. vacuum cleaners etc. as per youtube/gcn.
What do people think?
I've just moved house so don't have any space or my full toolkit to do much in the way of heavier maintenance. And the mechanic in Decathlon (the bike is a B'Twin Ultra 720AF) definetly didn't remove the chainset - I think I would have noticed that at least!
If I can't do this does anyone recommend any bike shops in the Crystal Palace area that are both trustrworthy and open (obv. for lots of reasons I'd prefer to do this myself atm)? Cadence is closed. Anyone had any dealings with Blue Door Bicycles or can recommend others?
B
Get yourself some Jagwire Slick Lube Liner - it's a thin white tube that it just slightly bigger than the inner cables (gear and brake).
Disconnect inner from the rear derailleur. Cut cable crimp off. Remove short outer. Slide Lube Liner over the inner (still in place) and push all the way through to the Bottom Bracket, then feed up the Down Tube to the Head Tube and out the cable stop. Now pull the inner all the way through and out. Put new inner in the shifter and then thread through the Lube Liner all the way to the rear.
You can trim the Lube Liner carefully and leave in place or extract it completely. If you leave it in place then make sure you don't cut or snag the inner with a blade and don't leave it too long else the outer won't sit snug in the cable stops.
As per pic - I did all cables (brake/gears) inner and outer. Still took 3x longer than it would take me to do a traditionally cabled bike.
https://amazon.co.uk/gp/product/B07JL9HFTD/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1
I ran it through the chainstay and the downtube in two different lengths (unlike photonic69 who seems to have used one length) as i found there can be a surprising amount of resistance through the liner tube, especially if you get any kinks or tight turns. I also found i needed to remove the BB cable guide which gives a little more space to play with.
Took me ages the first time, as wanted to be careful with the BB guide, frame inserts etc. but was 10x quicker second time round once its clear how it all works.
When i snapped a rear gear cable in the shifter, and only replaced the inner cable (not the outers), I also used the thread method with some success:
- Tie a thread to the end of the current cable (if you google this method there is a specific knot that works well.. but the name escapes me)
- Pull current cable out of bike (bringing thread through the internal routing)
- Tape thread to make sure it doesn't fall out
- Tie thread to new cable (using the fancy knot again)
- Pull new cable through frame with thread
Be careful to not pull the thread off the cable, and can be quite fiddly to get the cable through all the holes even though it is being guided by the thread. If you haven't left the old cable in, then you can pull a thread up through the frame with a vacuum cleaner.
Unfortunately I just moved house and most of my stuff is in storage. Have ordered that liner and just hoping it arrives quickly and that this is as easy as you say!
B
In your case though, you need the Jagwire internal housing or similar. Thread it over the old inner before removing the inner. You can then just insert the new inner without issue.
https://www.first4magnets.com/square-c36/12-x-12-x-12mm-thick-n42-neodymium-magnet-7-4kg-pull-p3489#ps_0_3588|ps_1_781
https://www.first4magnets.com/square-c36/12-x-12-x-12mm-thick-n42-neodymium-magnet-7-4kg-pull-p3489#ps_0_3588|ps_1_781
and I climb hills so badly