cs1

I saw these the other https://cgi.ebay.com/Shimano-FC-M569-...QQcmdZViewItem

Do they use standard chainrings? Looks like the big ring uses some kind of proprietary rings.

Tim

Rowan

Holy mongroly... the outer ring is rivetted to the spider. This must be a collector's piece. The fact it came from a bike shop liquidation indicates it has been in the big ol' parts bin out the back for a long, long, long time.

Undoubtedly, S Brown will know the history of this particular crankset... if not the guys in the Vintage and Classic forum.

Sixty Fiver

Damn... if that is original (and not some DIY job) it has to be some pretty early Deore stuff.

I've never seen the likes of that but that is the nature of working on bikes...there are always surprises.

ang1sgt

Really Early MTB LX or XT stuff had 5 arms on the gears. This must have been early 4 arm stuff in the mid 90's I'd say. They made a few of these riveted wonders and they had WAY too many complaints when the chainrings wore out.

Unless you can get a really good pic of the teeth, it's best to stay away from these.

I shudder just thinking about these!

Chris

HillRider

In the late '80's and early '90's Shimano's MTB groups were Deore LX, DX and XT and all used 5-arm 110/74 mm BCD cranks. I have a DX crank on a '92 Trek 1420 and an LX crank on a '93 Trek 7000 and both are 110/74 with 5-arms. The riveted stuff at the time was the really low line (Acera?) and similar.

This thing is really peculiar. Apparently the big ring is riveted to the spider but the middle and granny ring are bolted on.

Bill Kapaun

According to this site, they are 1997-98
https://www.fa-technik.adfc.de/Herste...o/Gruppen.html

Rowan

Maybe it's based on the design criteria that MTB riders spend most of their riding time in the middle and small chainrings, and so the larger ring, which is not so prone to wear because of less use and larger diameter could afford to be a permanent fixture by being rivetted on.

operator

Don't buy those. "As-is", you can't tell from the pictures whether or not the crank holes are ****ed or not.

cs1

At first glance, I thought the big ring was bolted on not riveted. Does that mean the spider unbolts from the crank arms in order to change the big ring? Didn't Shimano have a similar system on 4 arm XTR cranks? Pictures I've seen of the XTR, early version, showed the big ring almost looking like it was part of the spider. I'm thinking Shimano is changing stuff just keep the aftermarket parts guys out of business.

Tim

HillRider

I just went back to the OP's picture link. If you look at the inside face of the crank, there seems to be a lockring that attaches the entire spider to the crank arm and allows removal of all three chainrings as a unit. So, in theory, it looks like you can replace the rings. Where you would get a replacement is another question.

cs1

That's what I was thinking. And I thought Campy was proprietary! Shimano seems to be going in the same direction.

Tim

HillRider

I don't think this thing represents Shimano's future designs. I seems to be a one-time low cost model and is obsolete. Current Shimano MTB stuff is indeed proprietary in spider design and BCD but replacement chainrings are pretty widely available.

Retro Grouch 

The real question is "What are you trying to accomplish?" If you can buy the whole crankset for less than the cost of replacement chainrings who cares?

HillRider

You can buy a lot of replacement cranks complete for less than the cost of a set of chainrings. This is particularly true if the crank is one generation behind the times. I've gotten brand new complete 105 8-speed and Ultegra 9-speed triple cranks for significantly less than just replacement chainrings would have cost because their new generation replacements had just come out.

I believe the OP was just curious about the crank he saw offered on e-Bay and wondered how it was constructed. Thereafter, this thread went off on an academic discussion of its rather peculiar design features. I'm not sure anyone was seriously considering buying one.

cs1

Hillrider, you must be reading my mind. I've never seen that design Shimano crank until lately. I personally prefer the old style 110 BCD five arm design. But then again I'm a dinosaur and like old stuff.

Tim