Snapped sprocket

[Marshy]

My last session at the creek the other day was dramatically cut short. Fortunately no oopsie, but I was a bit disappointed to find that my (supposedly stronger) Superlite steel sprocket was no more. There's a bit of minor damage to the chain, swingarm etc, but I'm just lucky it didn't punt me off.

I've never seen this before. Anyone else?














All fixed:

[James_]

wow! you've done well there.

superlite = supershite, it seems.

[Turbo]

Pfffft!! Call that a snapped sprocket???
THIS is a snapped sprocket..

[Metal-Man]

Pfffft!! Call that a snapped sprocket???
THIS is a snapped sprocket..

[James_]

tough competition.

Needs two classes- assisted and unassisted. You both can have the title.

[zoidberg]

Oh wow! Glad you didn't get chucked into the weeds! Where did it happen?

[Marshy]

Oh wow! Glad you didn't get chucked into the weeds! Where did it happen?

Over the hill between 5 and 6. I coasted off onto the large runoff area on the outside of T6, and watched everyone zoom around 6 and up the hill into 8 for the rest of the session.

[Mr.Ed]

Was there a noise, a vibration, anything or did you just lose drive?

[Leezx10r]

Wtf! That's shit mate. V4 torque

[dan]

Deadset. Paper mache.

[Marshy]

Was there a noise, a vibration, anything or did you just lose drive?

Nothing until the loud grinding sound of the chain running down alongside the swingarm, between the sprocket and the swingarm. And no drive, obviously. Clutch in, and coasted to an uneventful stop. The chain outside the swingarm was to roll the bike into the recovery vehicle.

It must've been bending slightly during the day, because I fitted a different rim prior to that last session, and I noticed that the sprocket-holder bolts/nuts had started to come loose. It's not uncommon for one to slightly loosen over time, but I've never seen all of them loose before. Only slightly loose, but enough to notice. So I nipped them all back up before fitting the new rim. For those picturing a Jap bike setup, the Ape is very different. The sprocket nuts do up onto 'bolts' that then slide into the (fixed) circular cush drive slots. So there can be slightly more play than on a Jap bike.

[Little Mick]

photo time marshy... brain too frazzled from the week to think hard enough to picture the ape setup... that and a couple of bourbons...

[zoidberg]

Over the hill between 5 and 6. I coasted off onto the large runoff area on the outside of T6, and watched everyone zoom around 6 and up the hill into 8 for the rest of the session.

I am very glad for you it wasn't in the middle of a fast corner somewhere. Be a good place to watch from trackside though! cloud, silver lining etc.

[Nelso]

I just broke a few teeth off mine. It was on my ZRX1200 road bike a is a 530 chain. I've never bought an alloy Vortex sprocket since.

IMAG0200 (800x451).jpg

[Turbo]

Jeesus! If it ripped off 530 teeth, what's the point in alloy at all!!?

[Little Mick]

I just broke a few teeth off mine. It was on my ZRX1200 road bike a is a 530 chain. I've never bought an alloy Vortex sprocket since.

IMAG0200 (800x451).jpg

out of curiosity, how many kms on the chain Nelso? to break teeth you typically would need a load not evenly distributed on all teeth... that or a weak spot in a tooth.
Having said all that, for a roady I would recommend a 2 piece with steel outer.. Leave the full alloy for the track where you inspect it all the time..

[Marty]

I'm kinda weary of alloy sprockets I've seen so many fail. If you can destroy them on a 600 then a SBK got no chance. Especially on the road I think the extra dirt and grit running through them accelerates the wear. I've been running a super lite steel like the one marshy broke for years and it's great but only a 600

[Marshy]

I'm a big fan of using a lightweight alloy rear sprocket on track to provide the 'weak point' in the drive system. So if anything's gonna go, the sprocket will shear some teeth off instead of the chain snapping and going through the block.... or your leg. The flip side is you need to replace them twice a year, but I'm kinda ok with that as the cost of this insurance.

This Superlite sprocket is my first foray into anything other than an alloy rear, as it's surprisingly difficult to buy a 44T rear for an Aprilia - locally is impossible, and overseas is hard. Dunno why, every other size is readily available, it's just 44s that I have had all this trouble getting. So it wasn't by choice, but I was hopeful it would all translate into longer service life and fewer problems. Alas not.

Oh, for Little Mick, here's what the sprocket carrier looks like:

[AFAM DRIVE]

Hi Marshy,

One of our dealers notified us about this thread and I would like to find out more information please. Is this Superlite rear sprocket being used on an older RSV?

Most all Superlite RS7 Series steel sprockets have a recessed face for weight savings but we recently found out that this design will not work on older Aprilia RSV/Tuono models from I think 1998-2003. Aprilia rear sprockets mount differently compared to other brands like BMW and Ducati so we revised the 520 pitch sprocket to have a full thickness center along with a recessed middle section. This allows the sprocket to mount just like the stock 525 rear. Without the thicker center, the sprocket will be pulled to close to the swingarm causing poor chain alignment and rubbing issues.

Superlite Aprilia 35801R.jpg


Thanks,

Brian Lewis
AFAM Drive Systems Inc.

[Turbo]

I'm a big fan of using a lightweight alloy rear sprocket on track to provide the 'weak point' in the drive system. So if anything's gonna go, the sprocket will shear some teeth off instead of the chain snapping and going through the block.... or your leg.

I've heard this before too. Something along the lines of the alloy not wearing the chain as quickly as a steel one would do, too.
Perhaps Mr AFAM could clear this up?

[Marshy]

Hi Marshy,

One of our dealers notified us about this thread and I would like to find out more information please. Is this Superlite rear sprocket being used on an older RSV?

Most all Superlite RS7 Series steel sprockets have a recessed face for weight savings but we recently found out that this design will not work on older Aprilia RSV/Tuono models from I think 1998-2003. Aprilia rear sprockets mount differently compared to other brands like BMW and Ducati so we revised the 520 pitch sprocket to have a full thickness center along with a recessed middle section. This allows the sprocket to mount just like the stock 525 rear. Without the thicker center, the sprocket will be pulled to close to the swingarm causing poor chain alignment and rubbing issues.

Superlite Aprilia 35801R.jpg


Thanks,

Brian Lewis
AFAM Drive Systems Inc.

Hi Brian,

Thanks for posting. It's a 2013 RSV4. DID ERV3 chain. Afam front sprocket. All fitted new, together, 3 - 4 months ago.

I look forward to your reply, as I'm suspect about whether the chain is still good (possibly bent), and of course there's the swingarm damage, plus the destroyed sprocket.

[AFAM DRIVE]

Is it possible for you to email me a picture of the front sprocket?

[Marshy]

Is it possible for you to email me a picture of the front sprocket?

Yes, I'll take a picture tonight.

[Little Mick]

Pictures tell a thousand words marshy. Much easier to understand with the photos

[Marty]

Pictures tell a thousand words marshy. Much easier to understand with the photos

If the bolts are working loose, maybe you should consider lock wiring them, it seems pretty common to see that style of carrier lockwired.
105323d1329372801-rear-sprocket-carrier-installed-r1-quickshifter-016.jpg

[shippy__]

crazy sprockets

I remember sickos very well

[Marshy]

If the bolts are working loose, maybe you should consider lock wiring them, it seems pretty common to see that style of carrier lockwired.

Good idea. They've never really come loose before (occasionally over a few months, one will be a fraction of a turn loose), but obviously in this case with the sprocket starting to deform, they all loosened quite a bit in only a couple of sessions on track.

Pics for AFAM, front sprocket as requested

[Nelso]

out of curiosity, how many kms on the chain Nelso? to break teeth you typically would need a load not evenly distributed on all teeth... that or a weak spot in a tooth.
Having said all that, for a roady I would recommend a 2 piece with steel outer.. Leave the full alloy for the track where you inspect it all the time..

It was only a few thousand Km's from memory Mick; the teeth weren't very worn. It had been subjected to a few clutch up wheelies in its short life, but I was surprised when the chain started slipping and I found a heap of teeth missing when I inspected it. I replaced it with a steel sprocket and the same chain and steel sprocket are still on it to this day.
IMAG0199 (800x451).jpg

[Nelso]

crazy sprockets

I remember sickos very well

I remember the sound of Sicko being hit very well too. It still makes me cringe.

[Little Mick]

It was only a few thousand Km's from memory Mick; the teeth weren't very worn. It had been subjected to a few clutch up wheelies in its short life, but I was surprised when the chain started slipping and I found a heap of teeth missing when I inspected it. I replaced it with a steel sprocket and the same chain and steel sprocket are still on it to this day.
IMAG0199 (800x451).jpg

its actually scary how the teeth removal is intermittent, probably due to it initially letting go then the inertia builds up and takes another strike etc...

Be interested to hear from Brian from a design perspective on failure modes considered.

Cheers

Mick

[Turbo]

I remember the sound of Sicko being hit very well too. It still makes me cringe.

Sorry about that, chaps!
My brain has helpfully deleted from memory the impact itself....

[Nelso]

Sorry about that, chaps!
My brain has helpfully deleted from memory the impact itself....

Just glad you came out of it ok.