Boost crank or not boost crank?

[lechatnoir]

I'm building up an XC-type bike and the frame has boost spacing. Does this mean I need a boost-type crank? And if so, what is that exactly?

 

[fanievb]

yes you need a boost crank otherwise your chainline will be off

https://www.oneupcomponents.com/pages/understanding-chainline-for-optimal-1x-conversions-boost-and-non-boost 

[Pulse]

There is a ~ 1.6mm difference in chain line. You should be able to run normal crankset, depending on the size chainring you want to use. The chainring may cause clearance issues at the chainstays, but usually is no issue.

 

Edit: There are some offset shainrings available that will negate the need for boost specific crank, and normalise chainline

[dirtypot]

You don't have to have a boost crank.  If you already have a normal crank then use that and you'll be fine.  I use a normal crank on my boost frame.  No issues.

[Captain Fastbastard Mayhem]

I'm building up an XC-type bike and the frame has boost spacing. Does this mean I need a boost-type crank? And if so, what is that exactly?

Same as a normal crank, except with the chainline offset 3mm further to the outer edge of the bike. But as people have said above, you do not NEED the thing. Existing one will work. 

[lechatnoir]

There is a ~ 1.6mm difference in chain line. You should be able to run normal crankset, depending on the size chainring you want to use. The chainring may cause clearance issues at the chainstays, but usually is no issue.

 

 

yes you need a boost crank otherwise your chainline will be off

 

https://www.oneupcomponents.com/pages/understanding-chainline-for-optimal-1x-conversions-boost-and-non-boost 

 

so, it's a chainring-thing, not the crank itself? so a chainring with the required offset on a regular crank will be OK to get the chain line right?

 

many thanks

[fanievb]

so, it's a chainring-thing, not the crank itself? so a chainring with the required offset on a regular crank will be OK to get the chain line right?

 

many thanks

 

yes only a chainring with the correct offset (i made a booboo in my other post)

[splat]

so, it's a chainring-thing, not the crank itself? so a chainring with the required offset on a regular crank will be OK to get the chain line right?

 

many thanks

 

That's the way I understand it.

(unless the new BB is some strange width)

 

What crank and ring do you have now?

[lechatnoir]

That's the way I understand it.

(unless the new BB is some strange width)

 

What crank and ring do you have now?

 

Scouring the classifieds as I type this... Picking up the frame tomorrow and will get an idea of what's what

[Grease_Monkey]

Cranks are 100% the same. Your chainring will now be 3mm offset instead of 6mm. I would recommend getting the right chainring, don't wanna chew up an expensive cassette unnecessarily....

[Li Mu Bai]

OMG, dont go buy a new "Boost" crank.

You can use your old crank and merely change the chainring to one with a 3mm offset rather than the standard 6mm offset.

And save a lot too...

[Dirt Tracker]

I've been running around with a normal crank in a boost frame for the last year and the cassette, chain and rear of the world has kept turning with out a worry. Haven't been throwing away cassettes or sobbing over the endless stream of chains I've had to buy. 

[lechatnoir]

OMG, dont go buy a new "Boost" crank.

You can use your old crank and merely change the chainring to one with a 3mm offset rather than the standard 6mm offset.

And save a lot too...

 

I WAS a little clueless TBH, but nope... not buying a boost crank... more like buying A crank, as I have nothing at present. I see a crank in the ads, so now it's a boost chainring... or at least one with the appropriate offset

[Pulse]

I've been running around with a normal crank in a boost frame for the last year and the cassette, chain and rear of the world has kept turning with out a worry. Haven't been throwing away cassettes or sobbing over the endless stream of chains I've had to buy.

Agree. Unless one is running SS, the chainline changes every time one shifts gear; so chainline is almost never ‘optimal’.

 

BUT running the currecf chainline would minimise wear on the outermost cogs

[Dirt Tracker]

Oh, let's not forget the introduction of the DUB standard. 

[DuncanCT]

Here's a really good article explaining a number of different aspects...

 

https://www.wolftoothcomponents.com/pages/boost-chainline-and-chainrings

 

See on non plus bikes the chainstay clearance is one of the most important on modern bikes.