[Velorangutan]

Just tossing this info out here because I have found many who were unaware.

The only different between boost and non boost drivetrain kits is the crankset.

For Sram, the only different between a boost and non boost crankset is the chainring.

You can swap a Sram crankset from boost to non boost or vice versa just by installing a different chainring.

Hope this is helpful!

 

[Harold]

Just tossing this info out here because I have found many who were unaware.

The only different between boost and non boost drivetrain kits is the crankset.

The only different between a boost and non boost crankset is the chainring.

You can swap a crankset from boost to non boost or vice versa just by installing a different chainring.

Hope this is helpful!

Incorrect. IN SOME CASES, what you say is true.

Take, for example, RaceFace CINCH cranks (Turbine and Next in particular with the standard CINCH spindle - not the DH one like Atlas or SixC). What you say MIGHT be true if the standard 136mm spindle is used. But there is a 143mm boost spindle that can be used with either a boost or a non-boost chainring (flipped or not) which adds to the permutations.

It's not the only one.

 

[V1Rotate]

Just tossing this info out here because I have found many who were unaware.

The only different between (SRAM) boost and non boost drivetrain kits is the crankset.

For Sram, the only different between a boost and non boost crankset is the chainring.

You can swap a Sram crankset from boost to non boost or vice versa just by installing a different chainring.

Hope this is helpful!

Fixed it for ya. Like Harold mentioned, it's only really true for SRAM. Others it's more case-by-case

 

[Harold]

Fixed it for ya. Like Harold mentioned, it's only really true for SRAM. Others it's more case-by-case

I forgot that RaceFace also does boost spiders for 2x.

Don't shimano boost cranks only differ by the spider, also? At least, the ones that aren't the new direct mount ones.

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[Velorangutan]

Ha! Thanks guys. Good points! I think the main point was that the shifter, derailleur, chain, and cassette have nothing to do with Boost or super boost. I've had a lot of people think that they were.

 

[Chris_PA]

SRAM direct-mount boost chainrings have 3mm offset and non-boost 6mm. Does anyone know how much it really matters, this is only about the width of the teeth?
I was also always wondering if there is a good way to measure the offset, to see if its correct if converting a 4-spline crank.

 

[RS VR6]

^^The SRAM PF30 has a 0 offset chainring. Its completely flat. SRAM has a 0, 3, and 6mm offset chainrings. I've got em all. Threaded, PF92, PF30...long spindle...short spindle:madman:. My GF is picking up another bike...and that one has the DUB BB:skep:.

 

[Harold]

SRAM direct-mount boost chainrings have 3mm offset and non-boost 6mm. Does anyone know how much it really matters, this is only about the width of the teeth?
I was also always wondering if there is a good way to measure the offset, to see if its correct if converting a 4-spline crank.

No, it has nothing to do with the width of the teeth. Offset changes the location of the chainline relative to the centerline of the bicycle's frame. There are so many variations in frames out there that there is no clean answer about what's necessary. It all comes down to the frame you're installing it on. What's the rear hub spacing of that frame? What sort of clearance does the frame have between the chainring and the chainstay? How much clearance do you need for the tire?

For example, on my Guerrilla Gravity Pedalhead frame, my setup is all janky with spacing.

The frame has a 148mm (boost) spaced rear hub, except that hub is offset 3mm towards the drive side compared to a symmetric boost frame. I'm using RaceFace Turbine CINCH cranks with the 136mm NON-boost spindle and a Wolftooth BOOST chainring (3mm offset) that's FLIPPED (so the offset is away from the centerline of the bike) to clear the chainstay.

I could not run a narrower chainline because of clearance to the chainstay. I could run a wider chainline (6mm offset chainring flipped, to move the chainline farther from the centerline of the bike), but then my chainline on the bigger cogs would suffer. But if I wanted a bigger chainring, I would HAVE TO (again, clearance to the chainstay).

Unless you have a specific reason, it's probably best to just replace what you have with the identical spacing. If you want to change chainring size, it's worthwhile to check clearance to ensure it will fit.

 

[V1Rotate]

No, it has nothing to do with the width of the teeth. Offset changes the location of the chainline relative to the centerline of the bicycle's frame.

I think he meant that it only changes the chain line by the distance equivalent to the width of the teeth, not that the width of the teeth are different boost vs non boost.

That said, as finicky as 12 speed drivetrains are to get set up I wouldn't think one would tolerate a 3mm variation in offset very well but admittedly I've never tried it

 

[Chris_PA]

I think he meant that it only changes the chain line by the distance equivalent to the width of the teeth, not that the width of the teeth are different boost vs non boost.

That said, as finicky as 12 speed drivetrains are to get set up I wouldn't think one would tolerate a 3mm variation in offset very well but admittedly I've never tried it

Indeed I meant the lateral distance. I found a nice write-up on the spacing at oneupcomponents https://www.oneupcomponents.com/pag...or-optimal-1x-conversions-boost-and-non-boost

It seems there is only 2mm variation allowed for the spacing, which is really not a lot. They measure the chainline to the middle of the seat tube, I found this really difficult to determine exactly and my Epic has an offset seat-tube making it impossible.

I also wondered if I can adjust the spacing further by switching the bottom bracket spacer to the others side. I played around a bit using a 4-spline crank but in the end just got an older sram direct mount crank.

 

[Harold]

They measure the chainline to the middle of the seat tube, I found this really difficult to determine exactly and my Epic has an offset seat-tube making it impossible.

The "center of the seat tube" is really just a (usually) convenient spot to determine the centerline of the bike frame. You could just as easily base it off of the center of the downtube or something else you're able to measure adequately and is near the chainring.

 

[farfromovin]

Since we’re talking about Centerline and spacing, and I’ll keep it easy and just talk about SRAM, but is the front chainline on (super)boost 157 the same as boost? What, 52mm? I mean, the drive side flange is further out so we’d need either wider spindles or zero (negative) offset rings to compensate.

 

[Schulze]

For Shimano, just put on a normal crank and it works perfectly. I haven't figured out what their "boost" cranks are for yet, nor have I ever bought one. All my bikes are 148. If someone wants to tell me how it really is then I'm all ears.

 

[Harold]

For Shimano, just put on a normal crank and it works perfectly. I haven't figured out what their "boost" cranks are for yet, nor have I ever bought one. All my bikes are 148. If someone wants to tell me how it really is then I'm all ears.

That might work for some, but not others. As was mentioned above, boost cranks/rings/spiders are NECESSARY when the frame doesn't have clearance, or when you need space between the chain and tire. If you don't have those issues, then carry on. But my one bike with a boost rear end wouldn't fit your non-boost shimano cranks. So your experience is not universal.

 

[Schulze]

Well if the chain line is perfect then modifying the position of the ring for tire/frame clearance would be putting it out of where it is supposed to be.

 

[Harold]

Well if the chain line is perfect then modifying the position of the ring for tire/frame clearance would be putting it out of where it is supposed to be.

which is why the rear end of my frame is offset by 3mm, in part to fix that chainline problem.

 

[paxfobiscum]

For Shimano, just put on a normal crank and it works perfectly. I haven't figured out what their "boost" cranks are for yet, nor have I ever bought one. All my bikes are 148. If someone wants to tell me how it really is then I'm all ears.

I have boost wheels on both my Trek Fuel EX and my Trek Top Fuel. I also use RF Next cranks where I use so many different size chainrings (26t, 28t, 30t, 3t) that are both boost and non boost (the offsets between the two are pretty clear.

I cannot tell the bloody diference.

 

[Lone Rager]

I intentionally run a non boost ring on my boost bike as I have the clearance to do so and the chain-line somewhat favors the lower gears where I spend way more time putting the power down. Wolftooth had a white paper on the advantages of doing this. IDK if it's still up on their site.

 

[incubus]

Wolftooth have a great write up on this very issue....

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

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[jonshonda]

My Shimano Saint crankset (NOT BOOST) and now gouged up carbon chainstay would seriously beg to differ with this thread.