Chainring Countdown

 Bikes  Comments Off on Chainring Countdown
Sep 212011
 

Question: So the dirt world gave up on the five-bolt crank a while ago for no apparent reason. Now FSA is running ads for a three-bolt crank. Where will it end: a no-bolt crank held on by good intentions? What’s to be gained by the different bolt patterns anyway, aside from orphaning whole warehouses of perfectly good chainrings?

Approved Answer: The key here is something called “system engineering,” which refers to the habit component manufacturers now have of making all their stuff only work with their other stuff. Back when mountain bikes as a concept were a dark and terrifying forest of confusion, brands tended to make wild guesses about what might work best, usually by putting photographs of motocross and road bikes on the wall next to one another and opening and closing each eye real fast until the two sort of blurred. But at least manufacturers all stuck together on those decisions. Hence you had brake levers modeled closely after the lever on a Yamaha YZ 125, and mighty “standard drive” 5-bolt chainrings with at least 46 teeth. These were different times.

I’m pretty sure Shimano fired the first shots in the proprietary chainring revolution, but, like any slow descent into a corporate state, it was the willingness of the people to go along with the change that really allowed it. Your friend who had to have the Coda crankset with the built-in alloy chainrings? He did it. We all let chainring standards disappear because it was the ’90s, and we were all about buying a whole new crankset when our rings wore out; and because we really liked lightweight stuff.

Manufacturers started shaving away everything that wasn’t necessary, and it became apparent that designing your components to work with a countless array of alternate parts available from other brands made less and less economic sense. That’s why today we have only the stammering zombie remains of the last known chainring standard, the 64mm/104mm 4-bolt ring.

The Real Answer: For the past ten years, decisions about standards and innovations in the bike industry have been tightly controlled by a single overseer. The symbols and letter-like-slashes “Mittens” scratches daily into the leg of a dining room table in a home somewhere in Bayonne, New Jersey are taken as infallible engineering law, transcribed, and sent directly to Taiwan and China for the fabrication of new bike parts. This is the real source of most designs you see currently on the market.

Knog crap? All me.

Sticker Shock

 Bikes  Comments Off on Sticker Shock
Aug 152011
 

Question:
I have acquired a used XT 770 crankset. The big ring is trashed and I am going into sticker shock at Shimano’s replacement prices. Anyone have luck with other brands i.e. Blackspire, FSA, Race Face for this particular model? I have a hard time throwing down 60-100 dollars for a chainring that is not going to last long.

Answer:
I sympathize with your plight. Shimano does seem to subscribe to the same OE replacement parts pricing as car dealerships and national defense contractors. The big ring on a 770 series crankset actually has a 104mm 4-bolt pattern, the same pattern used by most other brands, so other rings will match up, but be careful. Much in the same way you can’t imagine being married to a unicorn or living in a world where dogs can drive, Shimano can’t conceive of a world in which people buy FSA or Blackspire rings and bolt them to their XT cranksets. If you know the history of Shimano chainrings over the past few years, you’ll appreciate what a miracle it is that even the bolt pattern happens to match now.

So the good news is that nearly everyone makes an aftermarket 104mm bolt-pattern 4-bolt 44-tooth ring that will match up to the bolt hole pattern on your 770 crankset. The bad news is that it won’t work as well as the Shimano. This is partly because Shimano just makes excellent cranksets and chainrings, but mostly because all Shimano parts are designed specifically to work only with other Shimano parts. They don’t intentionally prevent other rings from bolting on, but they don’t test for them either. This means that, even if something else can technically bolt up, it probably won’t mesh all pro-like to the crankset’s spider–it will most likely be slightly too wide or too narrow, and some rings may even need sections filed down if they’re making contact with the Shimano spider or arm itself. Generally, a Shimano crankset with another company’s ring on it also won’t shift as well, because chains, chainrings and cranksets are one of the things Shimano still does extremely well.

So it comes down to you: if you’re the ultra anal-retentive type who demands perfection, you should shell out for the Shimano ring. If, on the other hand, you’re more the frugal rebel type who can smile while pressing a shifter paddle a bit harder to convince the chain to shift into a less expensive big ring, look for the most basic-looking 44t 4-bolt, 104mm bolt pattern ring you can find and get your rogue on.