Do You NEED Boost MTB Cranks??

You've heard of Boost hub spacing, but what are Boost Cranks?

Boost cranks, over locknut dimension O.L.D., chainline explained!

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[JoelZieve]

Your illustrations are always so amazing and really help to make your points even more clear. Keep up the great work!

[mattdrange]

THANK YOU! it's so frustrating that more people haven't spread the word about how limited boost crank applications actually are in reality

[bodilidily]

Bike standards just get more and more insane.

[Justin-nyun]

The Shimano x100 cranks, are designed for boost. Which is why they are for 135/142/148 O.L.D and designed around chainline of 52mm. 51–53mm was apparently the best chainline for boost.

With frame design changing and wider tyre clearance needed then the 55mm chainline has become a thing. x120 cranks.

But the 6100/7100/8100 are still “Boost”

Unless your frame is designed around a 55mm chainline you’re better off with the 52mm chainline cranks

[djberg]

Great explanation, I’m 15years out of riding and just starting to wrap my head around all this….

Clear concise info, great work.

[mcjsantillan]

Was about to get a boost crankset because my hardtail has a boost rear hub. Turns out non boost is the way to go. Thank you for the explanation man!

[dirkisbrandt-umku]

...just to add that the FSA Modular (e.g., SL-K) crankset allows for nicely adjusting the chainline without changing Q factor by simply moving the spacer or installing a chainring with different offset (e.g., the Cannondale-compatible chainrings from Garbaruk with adjusted chainline dependent on tooth number). I converted my non-Boost MtB tandem from 3x10 to 1x12 and adjusted the chain line for the best shifting performance.

[KillerBunnyDog]

This is one of the better explanations I have seen. I like the fact that you pointed out the chain suck issues when they are not lines up properly. My spectral does that and it's annoying.

[TZZZ]

Thank you, excellent guidance, all clarity, no ego and no b.s. It’s rare on youtube. I’ve subscribed.

I have two questions related to SRAM Gravel cranks and chainlines which might be of interest to others:
1. SRAM mullet on gravel bike - why do bike makers spec ‘road’ cranks / 45mm chainline with a ‘mtb’ cassette? I’ve had to replace my Force 1x DUB ‘road’ cranks with DUB ‘wide’ cranks to acheive a 47.5mm chainline because the ‘road’ cranks chainring was only 1mm from the chain stay!  
2. Where on earth is the definitive online up to date guide to ALL Cranks, bb's, chainlines, spacer, combinations? ...It’s like looking for a needle in a haystack. EG: unless you have a SRAM BB, the published SRAM BB spacer guidelines for both road and wide cranks is incorrect, because SRAM BB’s have spacers built in. The bike brands don't have a full guide online, even for the parts they use, and the bb manufacturers don't either.

[MarioGoatse]

Bro you have a great way of sharing information. You explain and describe the issue perfectly. Not everyone is good at teaching or explaining concepts. I really enjoy this channel, and I appreciate you.

[pete]

Best explanation I have seen after watching dozens of 'chainline' videos - Thanks

[davidm]

Thanks for that explanation and drawing... It's something I've been thinking about but you explained everything like a professor!

[Tomzzzzzz]

This is the video that I’ve been needing! Thank you YouTube algorithm for serving it up and thank you for creating a great vid! I’m working on a brand bike build and figuring out the drivetrain has been a nightmare. My build is a 2022 V4 Santa Cruz Tallboy with Boost hub spacing. Santa Cruz doesn’t publish their chain line spec, but their support told me it’s 55mm for Shimano and 52mm for SRAM. Huh? I’m planning to run RaceFace Turbine cranks (1x 30T) with a Garbaruk 10-52 cassette (microspline) and Shimano XT chain & derailleur. I’m going to try a 52mm chain line using RF’s standard Shimano chainring. They also make a “wide” chain ring for Shimano. Hopefully it all works happily together! There’s a great article about the evolution (and controversy) around MTB chainlines on Radavist if you wanna deep dive into the hidden side of chain lines. Excellent read for bike nerds 🤓

[bobsaget]

Some bike manufacturers, like yeti tell you what their ideal chain line measurement for the specific bike model is. So when building a bike from the frame up see if you can find that measurement before buying the wrong crank set. When I was building my sb140 yeti recommended a 55mm chain line with a 148 boost spaced rear hub. So I referenced the crank set I wanted to use which was the race face era crankset and found it is offered in a 136mm spindle with a chain line of 52mm. So for my chainring I bought a 3mm offset wolf tooth chainring which enabled me to have that 55mm chain line. Had to add a couple 1mm spacers for the crank but it really was very straight forward getting the right chain line. Making sure you have the right spacers for your bikes bb spacing and the right spindle width is another thing that is easily messed up when building bikes from the frame up. Since shimano, raceface, and sram all have different width spindles for their cranks you need to take what bb you have into account before deciding what crankset to get. Or choose a crankset and then get a bb to accommodate it.

[dondeepiccio]

I'm new to mtb and currently building my own dream bike. With this video, it's clear that I have to settle for a non-boost crankset for my boost frame with a shimano slx boost hub rear. Thank you so much for this great explanation!

[dkubarek]

No questions here, sorry. I love these nerdy videos and how you keep the outtakes in. I learn some, laugh some each time. Keep it up!

[bennuendo]

Glad to see the illustrations showing up again. I love this format where you geek out on one thing. It reminds me of the one you did on brake temp.

[acruz]

Fantastic video because you explained to the audience what terms like 'boost' is. Great (the only suggestion I would make is, wash your bikes before you make a video, showing mud when you are supposed to be working on a bike on a stan it's just not acceptable and suggests the wrong practice to the viewer)

[marcellobittencourt]

Hey, man, first timer here. Your illustrations are awesome, so as your content. I did not even know there were boost cranksets to be honest, now I know! As feedback, your quality is impeccable, you clearly know what you're saying and make it easy to follow throughout the whole video. Just got subbed to learn more! Greetings from Brazil!

[baileydelelys]

Holy cow is this absolute best video on boost cranks. I could not find anything a month ago. It’s a way more simple concept that I thought. Thanks so much! Definitely a slept on topic by most.