CAAD12 - cables 'sticking' in frame, worn groove?

Hi, this is for those with experience of a CAAD12 over a long period.

I’ve totally recabled the whole bike after a few years use. I am getting sticking from the rear mech cable that’s baffled me, and wondering if the frame has worn inside and Is binding the cable.

The rear mech cable will slide down the right side downtube hole freely. If I then shift (as the cable pulls) the cable binds up and needs a pull from the mech end to release itself.
If slide in by hand you get the same effect, slides down the tube fine but pulling up it binds. A slight slide down releases it.

It has always been cabled right shifter into right side downtube hole and has had the ferrule on the cable outer. It has the outer teflon sleeve around the plastic bracket and the cable is routed under and away from the BB/crankset. The shifter works absolutely fine. I test cabled it up on the left side downtube hole to check and it shifted up and down fine (same shifter, mech, cable and outer). Cable is nowhere near the bottle cage rivnuts/bolts (had this issue with no cages fitted).

Can a groove wear inside the downtube hole where the ferrule goes which then catches the cable? Has anyone experienced this before with a CAAD12? Is there anything I am stupidly missing?

Thanks in advance.

When you say recabled, did you replace everything and use one brand for the cables and housing? One time I mixed Shimano/Jagwire cables/housing and had a similar issue that was very hard to figure out. Turns out the Shimano brake cable is 0.1 mm thicker than Jagwire. Switching to Jagwire cable made everything smooth.

I would suggest that you do an entire recableing (housing and cables). I would bet some housing is corroded or bent or full of dried up Gatorade and causing the binding. I would do both the brakes and shifters.

Mike

To clarify new cables and outers, brakes and gears. I will double check what brand the gear outer is but 99% sure both cables and outers are Shimano - I think they came in a ‘road shift cable set’ (as worked out cheaper than seperate, for brakes I have a huge reel of outer and drawer of cables that work fine ).

Gotcha - well that sucks! Did it stick before as well?

Mike

No it did not stick before. The cables were a little stiff and shifting pretty average but no binding the cable. That said I did remove a whole string of the PTFE cable coating from inside the frame. I am wondering if that was wedged in a groove and now removed it is catching the cable itsellf

I don’t know the cross section of the entry in the downtube, I would have thought the ferrule lined it up nicely (loose but can’t move about much) and the cable wouldn’t touch the sides of the actual hole.

Taking a photo up the downtube from the BB it looks like the hole is not round - but I cannot see how the cable would have made meaningful contact.

If it has I wonder about chasing the hole with a drill bit smaller than the ferrule end.

Photo up the downtube with a light shining down the hole - not a small round hole as I would expect?

The hole is of course at a slight angle to the photo.

I had a similar problem with the rear brake on my Caad12. The cable was rubbing on maybe a weld and fraying so the brake was not operating smoothly. I drilled out the internal cable holes on the frame and just ran a cable and housing all the way and haven’t had a issue since.

:slight_smile:

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That’s an idea, not sure that cable outer would fit around the crank spindle around the BB, will have a look later.

I’ve had binding issues with the rear cables at the point where the cables exit the downtube and go over the bottom bracket. Worth taking a closer look at how the cables are routing over that piece to make sure its not bound there. Probably not an issue for you as mine was caused by poor maintenance and it seems like you’re on top of all of that

Yup, unfortunately all free around there. Off to strip the crankset out and have another look now.

What baffles me is if it was a groove it wouldn’t only be me with this issue, and I am not even sure the design means there could be one

Perhaps it could be a miscast part inside but surely that would have been an issue at some point in the last few years of owning, not just now.

Just a theory for now but this image is what I think is happening. If this is right I cannot for the life of me work out why the internet isn’t full of CAAD12 owners saying ‘my shifting sucks’ then ‘WTF have they designed!’

I do actually have a bore camera over at my parents (who are isolating), that seems to be the only way I can look properly.

The angle of the hole from outside is just too much to see down properly, but from what I can see it looks like what I fear.

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This is going to sound silly and possibly patronising but it’s a mistake I made that gave a similar effect. Are you 100% sure you haven’t got the rear gear mech and the front mech cable crossed inside the frame? I once made that mistake

Is a good point but not the issue in this case.

If you run a single cable through the right side downtube port and put some tension on it will stick (no outer, mech, shifter).

I’ll have to put the frame to one side for now until can get the borescope and look inside properly.

Had a brainwave - I’ve ordered some nosed ferrules to guide the cable through. They should slide right through, it might be I still need to drill the holes slightly to remove the damaged material and clear the path.

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Early days and only based on riding around my road but shifting is dramatically better than ever, even when the bikes was new (I take a lot of care in sorting cable routing on my builds and use a little lube where appropriate).

These slide right inside the frame, no drilling, no messing. Makes me wonder if nosed ferrules should have been fitted from new given the design.

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Great to hear. I re-cabled a speed concept recently and front and rear derailleur cables where they go under the bottom bracket had these nosed ferrules pointed up into the frame. It was the first time I had seen them go into the bike, but it makes sense now (I re-cabled them the same way with the nosed ferrules).
Mike

It’s a neat solution to a problem that shouldn’t exist. Re-cabling that frame with all the right bits (and the crank out) is not really any longer or harder to do than an externally cabled bike. With the faffing. wow what a pain.

CAAD12 owner here as well with a few “tips”
Make sure you have enough “loop” in from the shifter to the entry to the frame with the external cabling so that you have as shallow an angle at all times possible. Not sure if you are using the “cross” method or the “same side” method for doing your wiring, but while the cross (left shifter into right frame hole) looks less sleek it does shallow the entry angle and avoid binding.

Also the whole area down at the BB is lots of fun and rife for issues, double check the plastic guard that inserts into the bottom of the BB isn’t damaged, pinched, and cables are running smoothly there. And again check the angle at which the cable exits that piece and heads into the chainstay.
Same then again for the rear “loop” of external housing, too short and its going to bind.

One trick you can do before cutting the cable is one it is all run, before you cut anything pull some slack on the shifter and by hand pull the line backwards and forwards to see if you can feel the cable catching or sticking at all. It will be a good way before you cut and tighten down to ensure you aren’t having issues or having to cut and potentially buy another cable again.

All back together but after a few miles it catches again.

Can pull free by hand down at the rear mech (really hard!) then after a few shifts to a lower gear it locks up again.

Shifter and rear mech definitely working.

I thought the nosed ferrules might sort it but the outer guide must be soft enough and cable tension high enough to get back into the groove.

Really frustrating.