When a chain breaks, what's it usually damage?

When my chain snapped it just went out the back and make cool sparks for everyone following me at night. Maybe the F4i is just that manly and tuff.

 

Steve Rapp's chain flew out the back (2012 Road america I believe) almost hit the rider behind him.

 

that is literally the only time i've seen a pro racers/pro prepped bike toss a chain that i can remember.. (aside form someones junior cup wrapped one up at NJMP last weekend). And that was a wicked powerful superbike.
On a club racers bike, if it happens, you can chalk it up to neglected maint. Either 1 or more component's are way worn, or it was too tight or too loose, or the master link was installed improperly. (my opinion, having been at this for 15+ yrs)

Replacing chains 1 time a year (if you race a typical season), and tossing any sprockets that show sighs of sloped teeth, learn how to install a rivet master properly.. really hard to screw up.

 

I've seen bikes in SBK, MotoGP and IOMTT all break chains. Cost McGuinness a win one year.

 

your typical club racer isn't riding a 240 hp bike, with a 520 chain, they are riding a 140 hp or less bike, with a 520 chain. I'd still think it was a one in 100,000 product failure of a good chain.. it was a cheap chain prone to failure, or install of master link done wrong (yes, rare considering pro teams, but it can happen) ..
if the potential for chains just "failing" was a real concern, it would happen way more often. Just my thoughts anyway.

 

@Black89: Damn. That seems completely unimaginable.

I've seen an OEM's pin backing out, caught in time...may explain other Ducatis that lost their sidecase.

 

To answer your question the chain usually breaks under load, therefore it is the top side. Sometimes they sling through the cases and other times they shoot out the back. I have never seen a broken chain wrap around the rear sprocket, i have seen a chain jump off and do that. Dirt bikes often have a guard/cage around the front sprocket to stop broken chains from hitting the cases.

 

Way back in the days of FZR400s, I had a chain break just after taking the green flag and bust the countershaft sprocket cover and the clutch plunger rod. And the left heel off an Alpinestar boot.

 

Chains break when they are not replaced by mileage. The R3 (racing "upgrade") chains are bicycle chains, they should be replaced every weekend or they will definitely break. Damage can be comprehensive, including broken crankcases. A new chain is very cheap insurance. Just do it.

 

Those 415 chains suck. We ran a DID 520 ERS2 non o-ring chain on Zayat's R3. A very light racing chain designed for 250 gp bikes. It's not easy to find but it has very little resistance and plenty strong enough for a 54hp R3 with cheater cams....

 

Tsubaki makes one as well very spendy but super nice.