120mm BBSHD build: Motobecane Sturgis Bullet & 20 Ah Triangle Pack

[SkOrPn]

JPLabs


Hey first post here. I been lurking for a while now here and there on many forums and researching ebike tech for at least a decade now. However, until now I just didn't think eMTB building was ready for me yet. Three years ago I almost picked up a bbso2 but backed out at the last second for a few reasons.

But your build and many other's have changed my mind lately (actually battery density has changed my mind mostly) and now that my last bike was stolen recently I think it's time for me to ask some questions. I'm starting here in your thread simply because of your bike model and size which happens to be exactly what I think I am wanting, but not entirely sure yet.

See I am only 5'7" with my bike shoes on, and ground to crotch roughly 26" or so and I weigh about 165lbs depending on the season. I can be as little as 150 lbs or as heavy as 170. This seems like my choice should be around a 15"-16" according to Direct bikes. But I want to be able to push in as big of a battery as I can build so I can actually use it to go ebike camping on a mtb trail that is over 400 miles long (grand enchantment trail) Here is another trail closest to my home, it clearly shows you the type of terrain I have to deal with mostly in my area https://www.mtbproject.com/trail/276...ail-trail-5619
So, I for sure believe I need at least a 17" medium, maybe even a 18 perhaps. 17.5" sounds like a winner, but I have no clue. With zero ebike experience and zero fat tire experience it's just overwhelming at this point. My last bike build was late 1999 and it was a hybrid build. It just disappeared out of my drive way too.

Anyway, will this Sturgis fit a rider my height with a 30-40 ah triangle pack? And do you consider it a good fat bike for sand, mud and Rocky terrain? I have seen so much data now on hundreds of bikes that I am seriously dead locked and confused on where to start. I am a DIY'er type and can build practically anything and routinely build my own tool batteries. I could build a bike from the ground up without any worry what so ever but with hundreds of frames and parts to select from I simply can't decide, lol. So instead of building a bike, I am thinking about just getting a complete Motobecane + BBSHD kit and upgrading bike parts as needed. Save my sanity from all the sourcing parts.

So do you really like the 17.5" Sturgis and will it be fine for a 165lb 5,7 guy? Thanks for your thoughts on this fat bike. I am really curious if I found a good fit for me in this model. Thank you

Best regards
Rod

Here is another long loop trail I have ridden before. I have many more, some completely undocumented.
Here is the 27 mile one that I can't do any more on a non-motor mtb.
Monzano Monster: https://www.mtbproject.com/trail/720...o-monster-loop (will directly connect to the GET, if you know how)
GET: http://www.simblissity.net/get-home.shtml (mostly unknown and undocumented and walking distance from my house)
GET Bikepacking: http://www.bikepacking.net/routes/gr...antment-trail (I would like to try this idea with a ebike someday)

[JPLabs]

HI Rod. Welcome! This is a good place for those questions, sure. My opinions related to your questions follow.

Size of rider:

My wife's bike is the same build, and she's 5'4". She can barely clear the top tube, but it works for frame size, by that measure. She needs to be careful off road, but you are taller so may have some margin. This is with Snowshoe tires, not the XL, the older 4.6 (? 4.7?) that came on it. With XL or any true 5" class tire, it's too tall for her.

The sag on her fork is more, also to help keep it low. It's that close! I don't know her inseam, unfortunately. Pretty short legs. I'll ask and update later.

EDIT: 27" inseam.

Seat height was easier. It was a little tall, stock. I just shortened the seat post a few inches so it goes further down all the way, now it has plenty of range for her. All good. I don't have room for a Thudbuster on her bike, but the seat is plenty low. It looks like there's even a little room to trim the frame, to lower it another 20mm maybe, if needed. With your height, you might fit a small Thudbuster, perhaps the full sized one?

Suitability:

I love the fork. It has suffered from the collapse in sub zero temperatures, but I added some shock oil to the air chamber, and that stopped. (oil isn't supposed to be in there).

I will say, my Bluto is finally in need of service. It works, but now has more friction than stock. It's not fluid and smooth like hers still is. That's something over 6k miles, not especially rough use, but plenty of bumps and trails. If I hadn't dumped shock oil where it didn't belong, maybe it would still be fine. I voided that warranty..... I'm real picky about fork stick-tion, though. I put Krytox oil on the foam oil keepers, to make them glassy smooth, and clean the tubes and seals a lot more than usual. Average owners might not notice what I think is 'worn out'. It's certainly still working, just not 'gliding up and down all the time' as I prefer. And as it is capable of doing.

There's a cold weather seal kit for the Bluto, too, if frigid temps are in your plans. I think I might even have one, but since the fluid fixed the collapse issue, I haven't installed it yet. Will, at rebuild.

The frames seem stable, the forks stiff enough, with that nice through axle to lock them parallel. Handles nicely on paved turns through braking and leaning, with no apparent twitchiness. I only weigh about 130 though. I think it's a good, stout frame design, in general. But a heavier guy may find it a bit more flexible.

Durability:

Her bike has far fewer miles, maybe 1200, but a crack has recently appeared at the LH rear rack mount lug. Cracked paint, only at the top weld, that I can see, anyway. Likely the lug has at least moved (yielded), if not started to crack the metal. The rack screws had loosened; that didn't help, I'm sure.

I carry 10 lbs or more in an Ibera Rack Pack, on bumps. The RACK broke on MY bike, but not the frame.

The frame is evidently asymmetrical for rear racks, so expect to have to bend one a bit to get it centered and level. The Iberas, anyway. And they don't bend easily! Seem heat treated.

Battery Capacity of 30-40 Ah:

If you filled the frame triangle with cells, you could exceed 20 Ah for sure, there is room for another couple rows of cells, probably, above the 98 cells I carry. 30 Ah with high capacity cells, maybe? But to get to 40 Ah, I think you'd need to double up rows someplace, I doubt you could pull that off in a single layer triangle.

Hope that helps your decisions!

[SkOrPn]

HI Rod. Welcome! This is a good place for those questions, sure. My opinions related to your questions follow.

Size of rider:

My wife's bike is the same build, and she's 5'4". She can barely clear the top tube, but it works for frame size, by that measure. She needs to be careful off road, but you are taller so may have some margin. This is with Snowshoe tires, not the XL, the older 4.6 (? 4.7?) that came on it. With XL or any true 5" class tire, it's too tall for her.

The sag on her fork is more, also to help keep it low. It's that close! I don't know her inseam, unfortunately. Pretty short legs. I'll ask and update later.

EDIT: 27" inseam.

Seat height was easier. It was a little tall, stock. I just shortened the seat post a few inches so it goes further down all the way, now it has plenty of range for her. All good. I don't have room for a Thudbuster on her bike, but the seat is plenty low. It looks like there's even a little room to trim the frame, to lower it another 20mm maybe, if needed. With your height, you might fit a small Thudbuster, perhaps the full sized one?

Suitability:

I love the fork. It has suffered from the collapse in sub zero temperatures, but I added some shock oil to the air chamber, and that stopped. (oil isn't supposed to be in there).

I will say, my Bluto is finally in need of service. It works, but now has more friction than stock. It's not fluid and smooth like hers still is. That's something over 6k miles, not especially rough use, but plenty of bumps and trails. If I hadn't dumped shock oil where it didn't belong, maybe it would still be fine. I voided that warranty..... I'm real picky about fork stick-tion, though. I put Krytox oil on the foam oil keepers, to make them glassy smooth, and clean the tubes and seals a lot more than usual. Average owners might not notice what I think is 'worn out'. It's certainly still working, just not 'gliding up and down all the time' as I prefer. And as it is capable of doing.

There's a cold weather seal kit for the Bluto, too, if frigid temps are in your plans. I think I might even have one, but since the fluid fixed the collapse issue, I haven't installed it yet. Will, at rebuild.

The frames seem stable, the forks stiff enough, with that nice through axle to lock them parallel. Handles nicely on paved turns through braking and leaning, with no apparent twitchiness. I only weigh about 130 though. I think it's a good, stout frame design, in general. But a heavier guy may find it a bit more flexible.

Durability:

Her bike has far fewer miles, maybe 1200, but a crack has recently appeared at the LH rear rack mount lug. Cracked paint, only at the top weld, that I can see, anyway. Likely the lug has at least moved (yielded), if not started to crack the metal. The rack screws had loosened; that didn't help, I'm sure.

I carry 10 lbs or more in an Ibera Rack Pack, on bumps. The RACK broke on MY bike, but not the frame.

The frame is evidently asymmetrical for rear racks, so expect to have to bend one a bit to get it centered and level. The Iberas, anyway. And they don't bend easily! Seem heat treated.

Battery Capacity of 30-40 Ah:

If you filled the frame triangle with cells, you could exceed 20 Ah for sure, there is room for another couple rows of cells, probably, above the 98 cells I carry. 30 Ah with high capacity cells, maybe? But to get to 40 Ah, I think you'd need to double up rows someplace, I doubt you could pull that off in a single layer triangle.

Hope that helps your decisions!

Hello and a big thanks for replying.

Well this model seems doable then. I never built a triangle battery before, so I am just guessing on needed capacities (looks like fun though). I wanted to build a cheap repurposed pack from say laptop, modem backup packs, etc as a starter pack. But then transition into the 3500 mAh Panny GA's eventually over time. I LOVE how that Luna bag completely fills in the triangle.

Wow, so you have only two years on this bike and are at 6K miles or so? I never calculated mileage before so I have no idea how many miles I would ride per year, but 3K does sound like a lot more than expected. I might use it everyday though. So the Bluto isn't holding up as much as you had hoped? Hmm, interesting. I am 35 lbs heavier and want something to last a bit longer out of the box, but that sounds reasonable. I never had a suspension bike so not sure what to expect. It's the tire quality I am more worried about. I hate flats, but who doesn't. lol

There is another suspension I see on the Gravity, RST Renegade and it's a 100 less, but with fairly OK reviews. I just do not know if that bike works with the BBSHD. So I am still in the research phase. For now I am wanting this Sturgis for the Bluto and straight top bar (I don't like those weird shaped tubes, they make me think they are less sturdy like a break point already built into the bike, haha).

My next step is to go test a Fat bike without any suspension, just to see what a solid fork feels like on Fat tires. Although I want suspension (Im 52 years old now), I might as well know what it is like without it before hand. Besides, I could always get that later, right?

Anyway, thanks for the bike report after two years. This is fantastic information and I thank you for sharing it. TIP: Oh, and hey if you ever need a good place to host images in the future, use imgur. I have been using these image sites for two decades and photobucket started going downhill (lol pun?) well over a decade ago. I use imgur exclusively now and have been for a long time without any failure at all. Thanks again for the Sturgis eBike report, it's much much appreciated.

[JPLabs]

I appreciate the Imagur tip, I'll check that out.

I'm riding 100 miles a week in nice weather, nowadays. I haven't had a flat, yet. punctures, several. Tubeless tire setup in my bike has prevented flats, so far. wife's bike still tubed, no punctures, yet. I ride road shoulders with glass and debris, but not thorns and cacti, like out west. those guys have it tough for flats.

[SkOrPn]

I appreciate the Imagur tip, I'll check that out.

I'm riding 100 miles a week in nice weather, nowadays. I haven't had a flat, yet. punctures, several. Tubeless tire setup in my bike has prevented flats, so far. wife's bike still tubed, no punctures, yet. I ride road shoulders with glass and debris, but not thorns and cacti, like out west. those guys have it tough for flats.

Haha, yeah we have goat heads and cacti here, and the other debris. Well, I think I have changed my mind for the thousandth time. I been trying to piece together a sub $2000 mtb ebike build that I could do from the ground up. After much calculations the Sturgis seems way out of my budget, if I want to mod it to my exact specs that is. And locking down the perfect frame seems to require test rides.

So, to be on the safe side I believe I am now leaning towards a 16" (since I can't test larger) and building from the ground up using either a naked Motobecane or the Gravity Monster frame. What I am after is almost exactly what you have but I want to completely redo the drivetrain to almost exactly like in the video below.

https://youtu.be/PzFzHrqsywU

Oh and haha, I made a mistake with the inseam. I should have used the book method but I believe I could stand flat on my feet so long the top tube is no higher than 28". That will be snug though. So that, and not testing any bike frames is why I am being on the safe side. I am not that worried about it, but I might as well put some effort into proper fit. I want a long lasting reliable end result. Thanks again