Chain snapped - advice please.

Guys, sitting here on the side of the road waiting for recovery. Chain snapped and ripped up the back end of my bike, undertray, rear seat cowling, indicators all gone. It caught me too and has gone through my leathers but I?m ok. Missed my missus who was pillion completely. I can also see the something popped up from inside the front sprocket cover... see pic, any idea what that could be? My engine management light is also on. Any thoughts? I?m also a little miffed cos it was only serviced 1500 miles and two months ago, am I wrong to think they should have recommended it was changed or is that unreasonable after that distance? It could have killed me and the missus had that come off at the wrong moment. Advice much appreciated.

Firstly, I am glad you and your better half and ok.

Metal fatigue is very hard to 'see'. A chain will grow a certain amount over time, and yes that should be within certain tolerances.

1. Was the chain oem? If not which chain was it?
2. How many miles?
3. Its a bit post event but had you checked the slack was ok?

(Not sure on whats moved behind the cover)

- Alex

Chain

Unfortunately chains do fail. We had a red flag last week at Snetterton caused by this very reason. If it was the OEM chain you could perhaps approach your BMW dealership and see what they say. A chain is classed as a consumable part which requires owner maintenance so the response from them could go one way or the other. I?m glad you managed to stay upright as I?ve seen a few accidents on track caused by chain failure that didn?t end so well.

Thanks guys, yeah we are ok thankfully, just a sore leg where I got whipped. It was an OEM chain, and probably due for change given I?ve just had a 12k service but they did say it was ok. Any thoughts on that pics and why my engine management light might be on?

Metal bracket looks like front sprocket retaining plate. But hard to see. I would take the sprocket cover off and see what has happened. Glad you are ok. It could have been alot worse if the chain had hit you or your pillion.

Glad you are OK. The displaced bit will be obvious when you take teh sprocket cover off. Ive niot done it on teh RR yet but teh XR has an aluminium shaped strip that looks like it to stop the chain jumping a tooth or trashing the engine if it snaps. If so yours worked!

For what its worth chains can go REALLY fast. I adjusted my chain on the XR prior to riding to Jerez two weeks ago. It needed a tiny bit of slack taking up but was OK. By teh time I reached Bordeaux which is maybe 650 miles into the journey the chain had stretched in a properly scary way. It freaked me out a bit and I had little option but to ride on and avoid heavy acceleration or engine braking. I took the chance and made it to Jerez and back home OK as we had only two days to ride there, and one day back up to Bilbao as we did the long ferry home. Bike made it OK but my god the chain stretch when I got back was astounding. I feel like a) I am a very lucky boy, and b) it makes sense to have a waggle of the chain every hundred miles or so when it starts to get a bit older. The XR chain had only done 13k miles and was the OEM one. I used to get 20k on a chain on my RSV easy. Then again it had 40 BHP less and was lighter.

Think the leathers saved my ass....

Blimey!! They certainly did. Thats very "miss whiplash"!!

Chain

I suspect that all the damage pictured was caused by the chain failing. It most likely triggered the Engine Management Light to illuminate as well. You might want to check your swingarm and sub frame for damage as they often get hit by a flailing chain. Until you get it back to BMW it?s just not worth guessing what the extent of the damage is.

Chains are supposed to be more slack than tight. Its got to move through the full range of suspension travel.

- Alex

Oh woah, Glad your alright that could've been a lot worse if it locked the rear wheel!

I suppose cause you had a pillion it tightend the chain as you had more weight and when you went under hard acceleration it was streching and streching it. When you take it to BMW I wouldn't mention you had a pillion.

Chain

Felix said:

When you take it to BMW I wouldn't mention you had a pillion.

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That?s a great way to foster trust with your BMW dealership :hopelessness:. Especially if he used BMW Assistance to pick him and his pillion up...

Shouldn't matter.
If it was checked at the service it should have been ok.
Strictly speaking preload should be increased with a pillion to offset the additional weight. But not chain slack.

- Alex

Ouch.
Glad you are both ok and it’s a reminder to always ride with the correct kit on.
I’d hate to see what your leg would look like if you had been wearing jeans.

RacersEdge said:

Think the leathers saved my ass....

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Very pleased you're both ok, annoying but bike and leathers fixable.

alex said:

Shouldn't matter.
If it was checked at the service it should have been ok.
Strictly speaking preload should be increased with a pillion to offset the additional weight. But not chain slack.

- Alex

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Yep, the pillion will make no difference to chain adjustment or influence the chain snapping, re set up for a pillion, you don't have to change it but it's beneficial if you can (on a GSA it's just a touch of a button away ) on my Gixxer it's just a shock adjustment of half a turn more rebound and a quarter turn less compression, no need to change the preload although of course its all bike specific.

Amazing how much damage a chain can cause... it?s all minor compared to what could have happened of course but sitting here shaking my head the more I see. It?s even somehow managed to completely slice through the seat mount ffs, I mean how did it make it up there? There?s lumps out of everything. Think I?ll need to be sitting down when BMW eventually call...

Update...

Chain Damage

That's going to be very expensive.

Fk me....

Thats gotta be a new case half for sure