Derailleur hanger - sheared retaining bolts/screws

[overmind]

Has anybody come across this before? I wonder how common it is?

I was fixing a bike for a work team member. Below is the spec.
https://www.stows.co.uk/bikes/hybrid-bikes/2021-giant-escape-3-disc-hybrid-bike-in-silver__18464

Essentially, the quick-release rear axle had snapped. I managed to get a replacement on ebay from hopkinson_cycles which worked beautifully.

While I was doing the repair I noticed that the derailleur hanger was loose. The (2) screws which secure the hanger to to the frame has sheared, the screw heads were missing and just the screw part was still lodged in the frame, which I managed to remove with an optical screwdriver (somehow).

Has anybody seen this before?
(i.e. the heads breaking of the screw like that. The only thing I can think that may have caused is riding the bike
with a broken axle would put extra stress on the screw and cause them to break.)

Aside: The Giant Escape 3 disc hybrid is a strange bike. It seems to be a mixture of old and new tech. It has disc brakes but the rear sprocket is a old-style, 7-speed freewheel. I would have expected a cassette.

 

[fossyant]

May have had a knock - just need to source replacement's bolts you've got them out.

 

[gbb]

Sacrificial screws perhaps ? A deliberate design ?
In the event if excess stress, perhaps they're deliberately soft so they shear, protecting the frame, drop outs or hanger, ?

 

[bonzobanana]

Has anybody come across this before? I wonder how common it is?

I was fixing a bike for a work team member. Below is the spec.
https://www.stows.co.uk/bikes/hybrid-bikes/2021-giant-escape-3-disc-hybrid-bike-in-silver__18464

Essentially, the quick-release rear axle had snapped. I managed to get a replacement on ebay from hopkinson_cycles which worked beautifully.

While I was doing the repair I noticed that the derailleur hanger was loose. The (2) screws which secure the hanger to to the frame has sheared, the screw heads were missing and just the screw part was still lodged in the frame, which I managed to remove with an optical screwdriver (somehow).

Has anybody seen this before?
(i.e. the heads breaking of the screw like that. The only thing I can think that may have caused is riding the bike
with a broken axle would put extra stress on the screw and cause them to break.)

Aside: The Giant Escape 3 disc hybrid is a strange bike. It seems to be a mixture of old and new tech. It has disc brakes but the rear sprocket is a old-style, 7-speed freewheel. I would have expected a cassette.

Probably the next model up had the freehub and cassette. Reminds me of a Go Outdoors mountain bike. It had a decent frame, hydraulic disc brakes, reasonable suntour front suspension, XCM I think and a Altus rear derailleur but the actual rear cogset was a freewheel not a cassette so much weaker and not really suitable for taking the impacts to the rear of a hardtail when used properly off-road. I can't remember if it was a quick release or a solid axle but if a quick release easy to snap it off-road especially for heavier riders or those who are a bit too ambitious with the bike. My point is sometimes bike recipes or configurations are a bit strange with a major failing in one area.

 

[Cycleops]

Aside: The Giant Escape 3 disc hybrid is a strange bike. It seems to be a mixture of old and new tech. It has disc brakes but the rear sprocket is a old-style, 7-speed freewheel. I would have expected a cassette.

The lengths some manufacturers go to to save money. Or maybe Giant had access to or wanted to get rid of some cheap 7 speed shifters and mechs?

 

[overmind]

Sacrificial screws perhaps ? A deliberate design ?
In the event if excess stress, perhaps they're deliberately soft so they shear, protecting the frame, drop outs or hanger, ?

I had not thought of that. I think that is probably it (clever design). it would protect both the frame AND the derailleur hanger (which are not that cheap to replace (around £20 for a small chunk of metal) - and there are dozens of different types!).

In my case, the axle had broken and the bike had been ridden in that condition. The quick-release skewers were basically holding the whole back end together. When I removed the skewer the wheel essentially fell out of the dropouts with the derailleur assembly and the hanger all connected.

 

[fossyant]

You'll likely just need some countersunk hex bolts of the right size.

 

[wafter]

Bolts hold two parts together via the friction between the two surfaces generated by the axial tension in the bolts. If they come loose this allows both parts to move relative to each other; meaning that the bolts now have to react this force in shear and cause them to fail - although I'd expect some fairly significant loads being required to cause this... as long as they bolts aren't made of Dairlylea of course.

 

[Dadam]

Aside: The Giant Escape 3 disc hybrid is a strange bike. It seems to be a mixture of old and new tech. It has disc brakes but the rear sprocket is a old-style, 7-speed freewheel. I would have expected a cassette.

Sounds odd. I've got a 2019 Escape 2 disc which has an 8 speed cassette.

 

[bonzobanana]

Sounds odd. I've got a 2019 Escape 2 disc which has an 8 speed cassette.

Maybe the 'Escape 2' is a higher up model than the 'Escape 3'? So exactly what you would expect. Apologies if you were being sarcastic and I'm just stating the obvious.

 

[Dadam]

No not sarcastic it probably is the next one up. It confuses me sometimes when bike manufacturers have lower numbers for higher spec models