BCD

Why do we make standards? Just to suffer?

Like with a lot of bike components, most of the industry settled on a general standard for chainring BCDs roughly between 1980 and 2010. Then (as with cassette size, headtube size, bottom bracket size, wheel size, spoke standards, brake standards, bar clamp size, etc.) all hell broke loose. Fuckin thanks Obama.

Chainring BCD is simply the hole pattern that is drilled into your chainrings:

Its where the bolts go to attach the chainring to the crankset. You can see how, in a better, dreamlike, more civilized world, all cranks would have the same BCD. Meaning, whenever your chainring needed to be replaced (it is the part of the crankset that will ((hopefully)) fail before the rest), it will be easy to find a new chainring in the exact size you need and you can keep your favorite cranks and world peace is achieved.

What’s that? We live in hell? Oh right sorry I forgot. So yeah even for something so fucking simple as a pattern for drilling holes for a part that WILL eventually need to be replaced, we invented over SIXTY standards. Sixty. 6 mother fucking D.

And you can be honest with me. You already know why. We both know why. We are all made aware of the horrible truth of this world when someone first said to us “no, you cant use digimon cards in a game of yugioh” and our dialectical balls dropped right then and there.

Its money. Its the profit incentive of making your things incompatible with the competition’s. That’s it. That’s all it ever was. “Oh we invented this eccentric BCD standard that makes your cranks 0.5% faster (and will be obsolete in 3 years) you should drop a bunch of money to buy into our product line (which isn’t compatible with anything else)!” Fuck off.

Anyway there are only 4 BCD standards that matter. 130 5 Bolt, 110/74 5 Bolt, 104/64 4 Bolt, and 94/58 5 Bolt. These are the 4 bolt patterns that have survived the asymmetric bolt pattern apocalypse. And I’m mad that there is even 4. I would be totally content if we could settle on 110/74, which is currently the most popular. Of the 4 of these, my favorite is 94/58. It is the least common of the “Big 4”™, but it also allows for a tiny little 20 tooth granny gear. This shit has allowed me to climb the hills in downtown Seattle as if they were flat fucking ground. But I understand that most people live in far more reasonable topography so I get the appeal of 110/74 with its (weak, lame) 24 tooth granny gear. 130 is essentially only used for single speeds and internal gear hubs, for increased rigidity with big chainrings. I guess that’s fine. 104/64 is a fad from the 2000s (i think) that made new mountain bike triples incompatible with 94/58, but it is easier these days to find parts for 104/64 because it was successful in it’s insidious mission. 104/64 can only fit a 22 tooth granny gear so it’s inferior in every other way to 94/58.

In the last 10 years or so, replaceable crank spiders have become popular. They allow you to change the BCD of your crank to (essentially) whatever you want! That’s awesome, I love the idea. Now your cranks are compatible with every BCD. Problem solved. I mean, they created the problem in the first place, sure, but then they solved it! How nice of them!

But wait, in case you forgot, we live in hell! Nothing is allowed to be better for the consumer! Ever! Not even one little time as a treat!

Replaceable crank spiders not only have attachment holes for the chainring, but they also need holes to actually attach themselves to the crank. Guess what? Guess fucking what? That’s right! The attachment points for the fucking replaceable spiders are, themselves, not fucking standard. I dont know how many standards there are at this point but I know it’s over 5 and I’m sure it will continue to grow. Hell, Sram made their standard, the Sram 3 Bolt Spider, really fucking popular and a bunch of third party part makers started supporting it. Last year Sram announced they are moving to an 8 Bolt standard. Why? Fuck you, that’s why! Fuck everyone! It’s bullshit all the way down! WheeeeeeeeeeEEEEEEEEEEEEEEEEEEEEEEEEEEE!!!!!!!!!!!!!!!!!!!!!!!!!!