Uh Oh. Snapped Off A Hex Key In A Bolt Head.

[Foghat]

A salutary lesson in taking the time to review some YouTube video guides to bicycle mechanics before wading in inadequately prepared.

For anyone else not familiar with the nuances of installation and adjustment of these newer-style Shimano front derailleurs with this useful in-built tension-adjustment capability (namely FD-R7000 105, FD-R8000 Ultegra, FD-R9100 Dura-Ace, FD-GRX810 GRX), the adjustment screw should never end up wound so far into the mechanism body as to be unretrievable if such an allen key failure occurs or if the hex socket rounds out.

If one follows the steps in this chap's useful and very well-demonstrated guides, the screw should never end up so far in as the OP's here, and the unremovability misfortune evident in this thread can be averted:

Free To Cycle - front derailleur guides

Link to the specific point in his FD-R7000 (i.e. same 105 as OP's) guide to the relevant bit on cable tensioning and adjustment:

And when it comes to replacing the front derailleur cable on these, always remember to wind the adjustment screw back out sufficiently to afford plenty of adjustment travel for re-tensioning the cable......and pull the cable tight by hand as you tighten the pinch bolt, whilst simultaneously keeping the tabs butting against the stops!

 

[Lovacott]

A salutary lesson ...

For anyone else not familiar with the nuances of installation and adjustment of these newer-style Shimano front derailleurs with this useful in-built tension-adjustment capability (namely FD-R7000 105, FD-R8000 Ultegra, FD-R9100 Dura-Ace, FD-GRX810 GRX), the adjustment screw should never end up wound so far into the mechanism body as to be unretrievable if such an allen key failure occurs or if the hex socket rounds out.

Good info. I've looked at that and the adjustment cam is a good half turn away from its limit so I'd say it wasn't being over tightened.

But, even fully "relaxed", the tension screw head only sits out about 1mm out from the mech body so I still don't see a way of retrieving this situation.

All that said, it's not me who initially set this up. It was Halfords three weeks ago so maybe I might have a claim against them for the unusable adjustment screw?

 

[JhnBssll]

If you disassemble the mech, can you get at the other end of the screw? With the clamp bolt undone and the cable tension released the adjuster bolt should in theory be slack, a small drill bit on the other end might be enough to unwind it?

 

[Foghat]

All that said, it's not me who initially set this up. It was Halfords three weeks ago so maybe I might have a claim against them for the unusable adjustment screw?

Well I'd give it a go, as the Halfords mechanic must have failed to pull the cable tight enough when fastening the pinch-bolt, and possibly started off with the screw too far in as well, or not positioned the tabs correctly, or even had the shift lever in the wrong position. The screw simply should not be that far in when at the right tension and adjustment.

So whilst Halfords is not strictly liable for the problem arising from the breakage of your allen key, it is largely Halfords' fault that the situation cannot be retrieved without buying and installing an inline adjuster, or something more drastic. Therefore I would go and blind the shop manager and mechanic with expert knowledge of specialist front derailleur installation for these types of Shimano mechanisms, and demand satisfaction of some kind.....but work out your negotiation strategy first!

If inline adjuster does end up being the only resolution option, make sure you use a decent quality one, such as Shimano's SM-CA70.....and insist Halfords supplies it free of charge

 

[Lovacott]

If you disassemble the mech, can you get at the other end of the screw?

Indeed I can. Not so sure it's worth the effort though?

Not when an inline barrel adjuster purports to do the same job for a tenth of the effort.

 

[JhnBssll]

Indeed I can. Not so sure it's worth the effort though?

Not when an inline barrel adjuster purports to do the same job for a tenth of the effort.

It's a valid point I'd have had the mech in bits within about 5 minutes of shearing the allen key, then I'd have ruined the bolt and realised without a replacement I couldn't ride the bike...

 

[Lovacott]

I'd have had the mech in bits within about 5 minutes of shearing the allen key

The joy of getting old is that you can't be arsed to listen to anyone who doesn't agree with you 100%.

 

[overmind]

You seem to have come up with a satisfactory alternative to the adjustment screw. It's a bit sad really though; I was hoping you would find a way of removing the end of the hex wrench from the bolt.

My personal approach would probably have been to use a dremel to try a remove it but I can see why you did not want to take the risk.

 

[Ajax Bay]

How big is the diameter of your suggested dremel wheel, @overmind ? If the chord is 2mm how deep would it cut? Damaging the expensive FD would not be a risk; it'd be a certainty.

 

[overmind]

How big is the diameter of your suggested dremel wheel, @overmind ? If the chord is 2mm how deep would it cut? Damaging the expensive FD would not be a risk; it'd be a certainty.

I wasn't thinking of a dremel wheel/disc; more using the dremel to hold a drill bit. Some of the attachments in a dremel resemble drill bits, or you could even use a regular drill bit attached to the dremel head. From memory, I think one of the head looked a very small version of that machine in Thunderbirds "The Mole".

Then use the dremel in a similar way to how the dentists drills into a tooth; not a pleasant analogy admittedly. :-)

I was also wondering if you could use a reciprocating saw to kind of shake the end of the hex key out. Hold the corner of a bluntish blade against the stuck part of the hexkey and start the oscilliation. It might shake it loose.

 

[Scottish Scrutineer]

A salutary lesson in taking the time to review some YouTube video guides to bicycle mechanics before wading in inadequately prepared.

For anyone else not familiar with the nuances of installation and adjustment of these newer-style Shimano front derailleurs with this useful in-built tension-adjustment capability (namely FD-R7000 105, FD-R8000 Ultegra, FD-R9100 Dura-Ace, FD-GRX810 GRX), the adjustment screw should never end up wound so far into the mechanism body as to be unretrievable if such an allen key failure occurs or if the hex socket rounds out.

If one follows the steps in this chap's useful and very well-demonstrated guides, the screw should never end up so far in as the OP's here, and the unremovability misfortune evident in this thread can be averted:

Free To Cycle - front derailleur guides

Link to the specific point in his FD-R7000 (i.e. same 105 as OP's) guide to the relevant bit on cable tensioning and adjustment:

And when it comes to replacing the front derailleur cable on these, always remember to wind the adjustment screw back out sufficiently to afford plenty of adjustment travel for re-tensioning the cable......and pull the cable tight by hand as you tighten the pinch bolt, whilst simultaneously keeping the tabs butting against the stops!

That is a good video. I must admit it took me a while to get the hang of setting the R700 derailleur up.

 

[Lovacott]

I was also wondering if you could use a reciprocating saw to kind of shake the end of the hex key out. Hold the corner of a bluntish blade against the stuck part of the hexkey and start the oscilliation. It might shake it loose.

Yes, that would do my brand new bike a world of good.

 

[Lovacott]

That is a good video. I must admit it took me a while to get the hang of setting the R700 derailleur up.

The Shimano dealer instructions on the website are pretty good even if the illustrations are a bit crap.

I've got a couple of bikes working very sweetly by starting from scratch following Shimano dealer manuals to the letter.

Meanwhile, and with nothing to lose, I've just tried one of the many madhouse solutions proffered up in this thread to solve my own problem.

I now have a lost head nail stuck firmly with Araldite to the snapped off hex key and I'm going to leave it for 24 hours to harden off before seeing if it will budge.

Even if it doesn't work, it's at least a testament to the power of glue that it could do the following...

 

[overmind]

It might be worth trying JB Weld if that does not work (based on this video)

View: https://www.youtube.com/watch?v=XObmZIbHOzY

 

[Lovacott]

It might be worth trying JB Weld if that does not work (based on this video)

I just happened to have Araldite in the house. I've been using it for years and once it's hardened off properly, it's very tough stuff.

I do have a big spiral mix resin anchor skelly gun tube full of industrial epoxy, but I only have the one mixing nozzle so I'm saving that for another day.

My next step is to loosen off the cable so that the adjustment screw is not stressed and then see if I can remove the screw and fit a replacement.

Either that, or I could pull on the nail and see if the glue bond is strong enough to extract the broken hex key?