100mm or 120mm BBSHD?

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100mm or 120mm BBSHD?

Post by hbgb » Dec 06, 2017 12:27 pm

(Originally posted this to E-Bike Technical, but realized this is probably a better spot for it)

I'm trying my first build of a Gravity Deadeye Monster with a BBSHD and am having some trouble determining if a 100mm BBSHD will fit on the frame. I'm based in the US and buying from em3ev, so returns aren't really feasible, so I want to make sure I get this right the first time.

Despite bikesdirect stating that the 2018 Gravity Deadeye Monster has a 102.5mm BB, I measured it to be 100mm: pic (the caliper is upside-down- that's a 99, not a 66 :) ). My only worry is that the chainstay might get in the way of the motor. Recommended by this article, I measured 2.75in from the middle of the bottom bracket to get the width of the motor (side view, top-down view), and saw that I think I need about 5mm of space on the drive side to fit the motor next to the chainstay. From this article, Karl mentions that you can fit a bottom bracket that is 5mm smaller than the space needed, but that's right on the edge for my setup, so I'm a little nervous about pulling the trigger.

If nothing else, if I got the 100mm BBSHD and it was a little too short, I could probably grind away a little of the BB from the non-drive side and squeeze it on. I've never used one before though, so I'd really rather avoid that if possible. I've also read from spinningmagnets and elsewhere that a 120mm BBSHD works fine on a 100mm BB, so 120mm is probably the safer play if I wanted to be risk-averse. I just don't want to add BB spacers if I don't need to. Does anyone have any insight here?


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Re: 100mm or 120mm BBSHD?

Post by melodious » Dec 06, 2017 12:52 pm

https://electricbike-blog.com/2016/02/1 ... ing-guide/

The link will take you to the "go to" site specializing in all things fat & electricified. Several of his blogs deals specificity to BBS systems & Direct Bike's Deadeye Monster fatbike. Search around the site for an hour or two and your predicament should hopefully resolve itself. :wink:
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