All Mountain trail Bike build and advice.

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geosped   100 W

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All Mountain trail Bike build and advice.

Post by geosped » Jun 10 2021 8:54am

I'm gonna post some pics for those that are interested in a "real trail" bike. I posted good useful info on the pic's captions to make this easier to understand. Below are pics of a good bike if your intention is trail riding. This is like a Rubicon for Jeeps. It's heavy and beefy designed to go trail riding. It's got a very good component spec which should hold up better with the hard abuse of a 1000w motor. It's NOT a down hill beast and not meant to do large drops but can jump and is very capable all mountain bike. Bikes intention is to be a weekend warrior trail rider for a heavier rider. I' mostly ride blues (intermediate) to expert trails (black) very little jumping :-( At least not yet. If your a lighter rider under 200lbs I'd go with the BFANG BBS02 if your heavier over 200lbs I'm 235 I'd go with a BBSHD although the BBSHD is way overkill. It's way to much power and so far I've had 0 issues with the motor.

A couple of things and misconceptions for trail bike. This is an education thread and help you make an informed decisions when your looking for a donor bike. A lot of people use a FS MTB bike to start but and the information for Trail Riding can be misleading and you will quickly find your self looking at the wrong type of bikes. If you want to trail ride make sure you do the following when seeking out a good donor bike. If you follow these simple steps you will be a happier trail rider.

1) FRAME:
Make sure you pick a bike with a straight down tube. This will allow you to maximize how high you can stick the BBSHD up on the frame. Tubes with bends ultimately wont allow you to mount the motor high enough on the frame there by lowering your clearance meaning you will with absolute certainty be nailing stumps and large rocks when you go over them NOT GOOD! So forget Giant Bikes like the Anthem or Trance for example. This is not ideal for trail riding even though it's a great mtb. It does not make a good candidate for a diy emtb.
2) Battery Sizing:
Size your battery based on your riding style. Do NOT make the mistake of getting a 10ah or LARGER battery. There is no need and the larger battery only weighs you down. You dont need it and dont want it. In my case I'm 235lbs I use an 8ah 52v 21700 T40 Samsung cells. This battery allows me to ride for 20miles on intermediate to expert trails in North Georgia about 2hrs of riding and I still have some juice left over. If you ride more than that then go up to a 10ah. If you ride less than that then use 6.5ah. The 21700 cells are larger than the 18650's and provide plenty of discharge rate. The pack does not even get warm after a long climb or stretch.
3) Suspension Travel:
If you plan on riding TRAILS then do NOT GET A Cross Country XC bike as a donar. You will be tempted and there are a BUNCH of used bikes that fit the profile. But do your self a favor and get a "Trail, All Mountain, Enduro, or Down Hill" style BIKE ONLY!!!! The sweet spot is an All Mountain or Enduro. 140-180mm of travel. If the bike has 100mm of travel KEEP LOOKING!!!!
4) Wheel size:
A lot of folks say a 26" wheel is fine but I would disagree. A 26" wheel although your powered you do not have the same rolling resistance to carry your self over large obstacles. A 27.5 or 29"er is the ideal wheel size. Sure you can power pretty much over everything but it's much easier to roll over something where your not really slowing down you find your self loosing a lot of momentum. Find a bike with a 27.5 or 29" wheel. It will allow you to climb easier and more efficiently over anything and typically provide a bit more clearance underneath. They are also faster on the top end but slower on the start. The downside is there more expensive.
5) Motor Type:
For trail riding you want a mid drive so you can take advantage of your gears. Mid Drives are also more efficient when going uphill as they don't get heat soaked like a rear hub drive will. You also want the weight in the middle of the bike and NOT over the rear wheel. You need a good balanced center of gravity (COG). Smaller Chain Ring in front means more TORQUE Large Chain Ring in front means higher top end more SPEED. So if your mountain biking you want more torque. BUT be careful with a smaller chainring and chain line. You might not have enough offset with a small chain ring. For motors right now the options are fairly limited and BFANG BBSHD and BBS02 are the best bang for your buck options. There are better and more expensive options though. I use the BBSHD but the BBS02 is also a great option that provides plenty of power and is lighter and smaller but less power. Buy either option and you will be happy. Be carful when selecting a BFANG kit. These KITS IMO ARE NOT COMPLETE!!!!. You will need an after market chainring (lekkie or Luna), a cheap chain guide (keep chain from popping off), and shift sensor (cut's power to the motor while you shift) with out this you will tear up your drive train.
6) BB Bottom Bracket Length:
Make sure you figure out what kind of BB your using. There are a few good guides out. Measure the length underneath. BBSHD kits come in 68-73mm 73-86mm and 92mm they may even have a 100mm . They also have extension kits. For example my bike is using a Lekkie 86-92mm extension kit.
7) Nuances of newer frames and considerations:
Newer frames and or heavier duty bikes like All Moutain / Trail, DH or Enduro's may have ISCG tabs on the bottom bracket. Meaning this will interfere when you go to install a kit like the BBSHD. You will have to cut at least one tab off. Not a big deal with a Dremel but then again your cutting into your nice expensive bike. It can be a bit scary. These types of bikes will typically come with Press Fit Bottom Brackets so you will need an additional adapter and make sure you get the right size. Lastly chain line issues are a real issue as these beefier bikes are wider and dont allways align properly with the motor. So make sure you pay close attention to the chain stay clearance and chain line. Look at the Luna Eclipse chain rings they have a good tutorial on chain ring offset. My first emtb had a Lekkie 42T but this did not provide enough offset on my new bike so I got a Lunna 42T which has about 25mm of offset. Still wont be enough but it's the best I can do and NO I'm not taking an angle grinder to my BB. :bigthumb:

A few drawbacks about the BFANG BBSHD. Throttle can be jerky. Reprograming of the FW will probably be required. What works for me is using the Start Current Sensor to 6 instead of 10 and make sure to set throttle Mode to Current (under throttle settings) One of the con's of the BBSHD is It comes with a crappy chain ring which will need to be replaced, Get a Luna Eclipse or a Lekkie, Another con is it typically does not come with a Shift Sensor make sure you get one. You also need to get a cheap chain guide. Make sure you get one. You really should consider all of these factors when pricing a kit as if you want the best possible experience you should do all of this stuff. Ask me how I know. I will say that the BBSHD is a BEAST. It's been very durable and reliable. It's extremely powerful. To give you an idea. I climbed a hill with a 2018 Specialized elevo in turbo mode and it's far far less powerful from a performance perspective that my BBSHD. Things that will help prevent your chain from popping off: Chain Guide, Narrow Wide chain ring and clutched derailleur. IMO the best bang for your buck here is the chain guide. But you really want all three. The lekkie and Luna chainrings are all Narrow / Wide teeth pattern so your good there and most newer higher end bikes have a clutched rear derailleur like Shimano XT.

Some additional considerations. Crank Arm's. Typical MTB crank arms are 170mm. This provides a lot of torque but with an emtb you don't really need such a long crank arm. Consider getting a 165mm crank arm. This will lower your chances of getting pedal strikes when riding.

On my particular build the only thing that I'm missing right now is what to do with battery. I will more than likely create a mount right above the motor and place it there on some sort of platform and secure it. I like the look under the sadel but this is not ideal especially when using a dropper post if your looking to bomb down some trails. You got to get your seat all the way down. In my case I still have plenty of clearance with the seat all the way down but it's still not ideal. I'm putting extra weight up high.

Let me know your thoughts and If I'm missed anything.

NOTEABLE PICS BELOW:
The pic with the chainline. This is a horrible chain line. This is one of the issues when selecting a bike like this. As you can see it's already using a Lekkie 42T which has an offset of 18.3. I'm going to swap this out to a Luna Eclipse 42T chain ring which has an offset of 24.8mm providing a bit more help. I dont think it's going to be enough. The reason you want a straight chain line is to prevent premature ware on your chain, rear cassette and chain ring. Chain is going to take the most abuse.

Chain Stay Pic. It's hard to see but I have plenty of clearance for a 42T chainring with more offset. You want to make sure that the teeth of the chainring will not touch the chainstay. If it does you will need to use bottom bracket spacers. On my last bike I had used three 1mm BB spacers.

Chain guide IMO great cheap insurance. Look at the inside of the chain guide. It's obvious the chain is getting slapped around and the chain guide is doing it's job. With out this if the chain pops off it may scratch and or do more damage to your frame.
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Totally stock bike. Notice the straight down tube, 160mm front and rear shock. This is considered an all mountain bike.
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The bike after it's been completed. Only thing left to do is mount the battery on the downtube although. I really like the discreet look of the battery in the sadel bag.
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The wires and ISCG Tabs also this is a 92mm PF BB.
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The ISCG tabs that need to be cut away. Scary!!
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Cheap IMO necessary insurance $11 chain guide bought off Ali Express same goes on Ebay or Amazon for a little more. Make sure you get one.
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The biggest problem I need to solve for this build is the chain line. This is awful. Look at the bend in the chain line? arrr. Also note the silicone to prevent water from getting into the BBSHD housing. Good idea to put some silicone calking and use some dialectic grease on all of the connectors. To solve this issue I'm going to use the Luna Eclipse 42T which will provide a bit over 6mm more offset from what I currently have. It's not going to solve the problem but make it better.
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Chain Stay clearance. From this pic it's hard to tell but I have at least another 10mm of clearance.
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Last edited by geosped on Jun 10 2021 10:12am, edited 7 times in total.
2017 Breezer Repack 27.5 Team 92PF BB, BBSHD Mid Drive, EggBeater v2, Lekkie 42T Chain Ring, 8ah 52v.
2005 Specialized FSR EPIC Comp Disc; 68mm BBSHD Mid Drive, EggBeater v2,Lekkie 42T Chain ring EM3ev 17ah 52v
2005 Giant Anthem FS, BMC V2 Rear Hub; 9 FET 72V Infineon Brushless Controller (LYEN's Edition); 10ah Zippy 50v Lipo Pack

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geosped   100 W

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Re: All Mountain trail Bike build and advice.

Post by geosped » Jun 10 2021 8:58am

On the pick where the lines are run directly under the motor. DO NOT do this as you will pinch the lines. Run them one on one side and the other on the other side. This was a bad idea one that I corrected.

I bundled the wires and put some heat shrink. This is a little bit of added protection overtime wires can chafe and or get caught up on a branch. The heat shrink does add a little protection.

See the one pic where the wires have been rerouted on the sides of the red bracket. you dont want to have the wires under the motor.
Attachments
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This is what needed to be removed. This is the ISCG tab found on most types of DH, Enduro, Trail, All Mountain bikes. I used a dremel and sanding disk. Very easy just take your time.
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This is what not to do. Dont leave the rear brake and rear derailleur lines under the motor. Re route them to the side.
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I used a Lekkie Extension Kit to extend my 68mm kit to fit a 92mm Press Fit Bottom Bracket
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Shift Sensor is a must. With out it you will be slamming the gears every time you shift under power. Pick up on aliexpress for $15
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The brake and derailleur lines have been re-routed to the side. This is a must.
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heat shrink to tidy up the rat's next of extra wire left over.
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Last edited by geosped on Jun 10 2021 9:51am, edited 1 time in total.
2017 Breezer Repack 27.5 Team 92PF BB, BBSHD Mid Drive, EggBeater v2, Lekkie 42T Chain Ring, 8ah 52v.
2005 Specialized FSR EPIC Comp Disc; 68mm BBSHD Mid Drive, EggBeater v2,Lekkie 42T Chain ring EM3ev 17ah 52v
2005 Giant Anthem FS, BMC V2 Rear Hub; 9 FET 72V Infineon Brushless Controller (LYEN's Edition); 10ah Zippy 50v Lipo Pack

Grantmac   10 kW

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Re: All Mountain trail Bike build and advice.

Post by Grantmac » Jun 10 2021 9:44am

Either of the Bafang motors are a poor choice due to weak bottom bracket, horrible chainline, bad ground clearance and way too big of a chainring.
Unless your trail riding is extremely mellow that is, any jumping other than the smoothest of tracks they won't hold up.

Unfortunately your options are limited with the best currently available being a low voltage build with the CYC X1 Pro and a Castle Creations ESC or VESC running throttle only. Unfortunately not the quietest.
The Lightest drive which is supposed to be released soon is another good option so long as they get the BAC855 programming figured out which nobody else seems to have accomplished.

TNC   100 W

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Re: All Mountain trail Bike build and advice.

Post by TNC » Jun 10 2021 11:21am

Grant, I think that might be a bit of an overstatement on the 02/HD. There is one real negative that can't be argued, and that is ground clearance. Now, I will say that I measured the ground clearance on the demo Trek Rail 7 we have at the shop, and my Nomad has a tiny bit more measured ground clearance...about a 1/4". The benefit of the Rail is that it has a rubberized bash guard. After riding my Nomad/BBSHD setup in some rocky areas, I do have to pay a little more attention to the clearance on ledges and such...and make some concessions on approach. However, in the few spots where this occurs, the throttle becomes a big aid instead of just slamming into a ledge under pedal power only. I've kissed the motor a time or two already, but it was hard to even find a contact point...the motor case is pretty darned robust. But the motor does extend further than what you normally have for clearance, just not the kiss of death IMO. I was concerned about the wiring coming out the lower back of the motor, but it seems to be in a spot that doesn't get the contact I thought it might. I did wrap the main bundle with braided rubber fuel line as pictured below.

On your weak BB comment, are you saying it's weak in terms of breakage, or that it's a square spindle design, or is it the capture system of the motor with the non-drive side nut system? On the square spindle crank interface, I do wish it was something like the Ultra uses just for peace of mind. However, even in my younger years of more aggressive riding with drops and radical terrain, I never broke or wallowed out one of my crank arms. Using quality crank arms and proper installation and torque goes a long way. On the method by which the motor is attached to the BB, I was not fond of that design. However, I rode the bike quite a bit before making an additional retention plate and never had the motor loosen...see retention plate below. Using a curved, heavy duty rubber pad at the downtube contact patch and making an additional retention plate is just good insurance.

On the chainline, this is only a problem depending on the bike design. Geosped had a decent challenge because his BB width is a little different and he had ISCG tabs to deal with. On my Nomad and an '03 Santa Cruz Bullit I have, this motor did yield a less than optimum chainline with that factory chainring which was easily fixed with a Luna Eclipse 42T. Yes, it required a purchase of an expensive chainring, but it is a fix for the problem. My chainline on both bikes was right in line with my factory chainline. You are correct, however, in that all bikes are not a guarantee for a perfect chainline, but I'd say most 68mm-73mm BB bikes will work...just do some measuring and checking first. Some full suspension designs may always be a wild card in fitment.

On the gearing issue with a 42T chainring...yes...normally that would be horrendous on a pedal-only bike. But with a 9-speed,11-50 steel cassette...Box 3 and others...that is not a problem. It's not a problem because a BBSHD in particular has more than enough torque to cleanly pull through fewer gears and without all the small incremental jumps between traditional pedal-only drivetrains...and that's without unduly loading the motor in too high a gear. Initially I watched my watt guage on my 500C display very carefully, and as long as I wasn't trying to be ridiculous in a high gear situation while accelerating or starting from a stop, the motor was never challenged. This is where the BBSHD apparently shines over the 02 version. That's not to say one should just hammer willy-nilly on the pedals or throttle in any gear or aggressive situation. You have gears...use them. It just doesn't take as many gears or being in a super low gear as it relates to the terrain you're in.

So Grant, I sound like a rep from Bafang, don't I?...LOL! Well, maybe a little, but it's based on experiencing something I really didn't expect would be as good as it turned out. To be honest, I would rather have something like a Luna X1 with the Ultra in-frame motor that is designed like our Trek Rails and Specialized bikes at the shop. I'd rather have the Ultra motor rather than the nice Bosch units that are in our bigger hit Trek emtbs. I'm also a dirt motor guy, so more power is always appreciated...LOL! I think my SC Nomad is a superior bike in terms of handling and suspension on the X1 as delivered, so for the moment I'll stay with the Nomad/BBSHD. And we can't forget to mention the programmable aspect of the Bafangs to suit the rider and conditions.

I'm not finding a lot of warts on this setup, and those I did find are pretty much all solvable or easy to live with. And this may be the point you're making in your opinion. I think the Bafang mid-drive application for actual off road challenges is probably a better fit to a bike person who has some decent mechanical skills and riding experience. I'm not an Erv Kanemoto level mechanic or a Hans Rey level rider, but I'm not bad...LOL! The mechanical skills definitely helped in setup and dealing with the niggling annoyances that cropped up. And let's be honest. Most mountain bikers are not "sending it" out at Bartlett Wash outside of Moab. Most mountain bikers will have no issue on most of the trails being ridden and how they're riding them. I still contend that the BBSHD will perhaps do a little better than you're giving credit with proper setup in the proper bike.

And Grant, while I am differing with you on some of your takes on the Bafang mid-drives, my long winded encyclopedia here is in discussion form and not meant as an attack. Differing opinions are good for discussion...not cussin'...LOL!
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COAR   100 W

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Re: All Mountain trail Bike build and advice.

Post by COAR » Jun 10 2021 1:55pm

An XC bike might be a totally workable option if you're not regularly smashing through rock gardens or hitting large drops. The plus is the lighter weight will offset some of the motor/battery, and the frame triangle may be large enough to hold the battery. Just don't go full weight weenie to the point you're severely compromising strength. As TNC alluded to, most riders don't need extreme equipment and would probably be fine with a short travel bike (I've see some folks ride ridiculous stuff on 120mm), but personally the geometry would be a deal breaker if the head angle is too steep (i.e. twitchier, and sketchier going downhill).

A fully kitted conversion will most likely weigh 50-60lbs. Mine is closer to 50. Before building I was concerned about the weight, but now I barely even notice it until I have to lift the bike over a fence or load it on my car.

As for frames, it's probably best to stick with either steel or aluminum. I would worry about cracking the BB shell on a carbon bike tightening it the way I did on my steel one.

The controllers definitely need to be reprogrammed to be more usable on the trail. I went with a config that basically allows 5 lower power levels, and 5 higher power ones. Anything above 30% dramatically reduces the pedaling effort required - to the point I'm pretty much spinning out with a 30x11 on flat.

Image

And I don't think it was mentioned, but it will take some playing around to get the cockpit comfortably setup. I went with a thumb throttle and the 500c display, both mounted on the left side. You probably want the display close enough to easily change levels without removing a hand, however with a dropper post and the throttle mount, it's a bit of a reach.

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TNC   100 W

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Re: All Mountain trail Bike build and advice.

Post by TNC » Jun 10 2021 2:37pm

COAR, the weight deal is surprising, but maybe it's a little like a dirt motor. When you have good power, the weight isn't nearly as onerous...LOL! My Nomad weighs a hair over 50 pounds...without the battery...I use a backpack. What the bike loses in flickability it gains in stability. Coming from a dirt motor, it doesn't "feel" heavy underway, but you're right about loading and unloading the bike.

On the throttle I was using the Bafang thumb throttle. It worked fine but wasn't intuitive to me like a motorcycle throttle feels. One of the Luna full grip throttles fixed that, but the throttle is a very preferential thing for most. And I really don't use a lot of throttle except when I start to get stalled or off line like in some rocks where a blip of the throttle gets me going again.

HrKlev   100 W

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Re: All Mountain trail Bike build and advice.

Post by HrKlev » Jun 10 2021 4:41pm

Great thread!

The reason why I never went with a Bafang is the lack of torque sensor. I had another cadence based system as my first ebike, but I just didnt get used to it in the technical bits if the trail. I guess its a personal thing what you get used to. If I didnt find my own solution I would probably have given the bbs2/bbshd a try after I got fed up with my tsdz2.

BTW, I find the 27.5 trend is quite rudiculus, the difference between 26 and 27.5 is almost non existant. I understand the 29 size, but the 27.5 are nowhere in the middle between 26 and 29. Feels like it was just a thing to force people to upgrade rims, wheels, etc. Biggest reason to go from 26 to 27.5 is just the availability of tires.
Hubdrive as middrive, with torque sensing EMTB build: viewtopic.php?f=6&t=107622

6x6 conversion: viewtopic.php?f=34&t=109567

Grantmac   10 kW

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Re: All Mountain trail Bike build and advice.

Post by Grantmac » Jun 10 2021 5:38pm

I think probably I ride much rougher trails then most DIY ebikers.
Anything hanging outside the frame is going to get destroyed here and 28t chainrings are common. Square taper is definitely not going to hold up and neither are the tiny bearings inside the BBSx bottom bracket.

I think they are a decent drive so long as people manage their expectations and pick the right frame.

For me personally the right DIY hasn't come along yet so I'm sticking with leg power until it does. I got bored with my 2400w cyclone build because 60# is just too heavy even on a full DH frame.

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