Diamonback Overdrive Sport 27.5 gets a BBSHD

[Alan B]

My latest project needs a bath, and is not quite finished, but they are rarely ever really done, now are they? I'm writing a full article about this one, but here we can get into the nitty gritty and answer questions that an article can't always answer.

So to start it off, inside the triangle pack is a 52V 20AH Samsung 26f pack, the BBSHD has the Eclipse chainring and 3mm spacer, all from Lunacycle. Brakes are Tektro Dorado hydraulic eBrake 203mm with Bafang plugs from EMPowered Cycles. Rack and trunk are Topeak, seat is Bell Recline from Amazon. Charger is Satiator from Ebikes.ca. Water is San Pablo Reservoir from recent rains. Most of the rest is stock equipment on this 2016 Diamondback Overdrive Sport 27.5 medium.

I made a conformal spacer of Loctite epoxy putty to spread forces between the motor and protect the downtube, in an effort to avoid the damage that some have experienced if the motor works loose.

Thumb throttle and BBSHD controls on left, trigger shifter on right.

Stock bike weighs 31 pounds, BBSHD added net 10, battery added 13. So without trunk/rack it is about 54 pounds. A shark pack battery would get it down under 50 pounds but reduce the range by almost half.

I'm about to add a Batt-man to the setup to get better range anxiety management. Range is 25-50 miles.

This machine climbs like a mountain goat. Without getting hubmotor hot. :)

Here's the full article I wrote on this bike, which was published after this thread was started: https://www.electricbike.com/a-diy-m...eet-and-trail/

Any Questions?

[Brent]

Nice job as always Alan.
Clean and useful, great job.

Couple of ?'s
1. Is this a 68mm BBSHD motor?

2. Do you think with an appropriate amount of spacers that I could use a 100mm BBSHD ON A 68/73mm BB?

I own a couple of bikes I'm considering converting. One a 68mm BB touring bike with a Nuvinci N171 the other a Mongoose Dolomite with 100mm BB.
Without having my hands on the unit(I'm a hands on guy) and trusting your technical abilities(followed you for some years on ES) just looking for your opinion.
I believe it will widen my pedal stance but can you foresee any other issues. Won't hold you to it, just looking for an educated guess/opinion.
I'd like to have the flexibility of the 100mm unit as I'm still bike shopping and finding 73mm here and 83mm there, but could stop now if I could swap motor between my two bikes, fatty in the winter, touring the rest of the year. Thoughts?

Thanks for your time.

[Alan B]

Hi Brent. Thanks for your comments and questions.

This is a 73mm motor and fits the 73mm bottom bracket of this bike. My frame did require a 3mm spacer under the chainring to avoid the teeth touching the chainstay. Each frame may require tuning. A wider BBSHD and spacers on the bottom bracket could also fix this, but there are some potential issues in this approach. Aside from the mechanical and body mechanics disadvantages of wider pedal spacing, using spacers on the bottom bracket makes keeping the drive solidly anchored problematic. These drives depend on clamping the bottom bracket to hold them in place. There are teeth in the plate on the non-chain side that are designed to grab the bottom bracket and hold the motor in position. The recoil torque is toward the downtube, so the drive should be firmly against the downtube, otherwise it will almost certainly work loose. Any spacer on the plate side is going to negate the value of those teeth and make it more difficult to keep the drive tight. If the drive moves it is going to pound the downtube, and we have seen threads on ES where damage was done to the downtube. This is not to say it cannot be done, clearly folks are doing this, but some are having difficulty.

I was concerned about this tendency to loosen and damage the downtube, so I made a rigid conformal spacer in between the motor and downtube using epoxy putty to spread out the force which is otherwise concentrated in a very small contact area. Even with careful attention to tightening and using blue Loctite I did find the drive came loose once and I had to re-torque it. I was talking to Matt of EMPowered Cycles and he has done a lot of BBS02 drives. He said it is normal for them to require re-torquing once.

For a touring bike I wonder if the BBS02 would be a better choice, with 3 pounds less weight. I know I would not be too happy moving the motor, wiring, displays and throttles between bikes. The battery can be shared easily by purchasing extra bases or triangle pack coverings. The BBS02 fits 68mm but I see that for 73mm folks leave the outer nut off which I don't care for. So I would be inclined to use a BBSHD for a 73mm bottom bracket for a good fit. But for a 68mm frame the BBS02 offers a lighter weight and lower cost option if the extra power and heat dissipation aren't necessary.

For the Dolomite (or any fatbike), I wonder if the chain and crank arm clearance issues are better solved with a 100mm drive or a 120mm. Getting the chain by the tire, the chainring by the chainstay, and the nondrive side crank arm to miss the chainstay can be a juggling job. Consulting with folks who have done this exact combination would be helpful.

I'm considering using a BBS02 on a 68mm bottom bracket folding bike. For that build the reduced weight is attractive, and from what I've read the BBS02 is a very capable unit, albeit with a bit less torque. But folding bikes tend to lift the front wheel easily and may need torque limiting anyway.

I hope I haven't discouraged you Brent, you can move the drive between bikes, even though I am reluctant to do it, I understand some folks have a need to. Make sure the drive stays tight and protect the downtube. One might think a steel frame would be better here, but to make them light the tubes are thinner so dent resistance can actually be inferior to an alloy frame. Look for folks who have done exactly what you are trying to do, there should be some good experience to draw on. My experience has been good and fairly straightforward, but each bike presents a slightly different set of challenges.

Ride Safe,

[Brent]

Thank you so much for all the valuable info Alan. I tried searching out this info on ES but the signal to noise is a little high on some of those BBSxx threads.
I didn't realize there where teeth on the plate on the non drive side. This is where I'd need most if not all the spacers. So it sounds like my idea is a no go.
I'm with you on the BBS02 on the city/touring bike, it's likely all I need. Then again for $150 more and 3 lbs I can have more continuous power and more torque. I'd also be able to future proof should I decide to move onto a mountain bike. Plus there is always that I want more power thing. Decisions, decisions!
Thanks for the help and contribution.

All the best.

[Rix Ryds]

Nice job Alan! I did mine on a 2015 overdrive sport, including a NuVinci N360. Everyone with an ebike should at least try a NuVinci, they are awesome for ebikes! Went with a shark pack so my battery would lock on my bike. Next addition will be a second battery, present range is about 20 miles. Had thought of going with the BBS02 but am really loving the HD, it is truly amazing, and can haul my 220lbs up a22% at the end of my street.

[Alan B]

Thanks for the comments Rix. I may use a little padlock to discourage fiddling with the zippers on the battery pack. A second battery is also on my list. 31 amp hours would be awesome. I have 18S 32AH on the Borg. Really nice range.

Your post timing is interesting, I am reading about IGHs again, and just read a few articles about the N360. And the Rohloff, among others. So many choices. The N360 sounds very interesting. I want to do a trike, perhaps it would be good there. Not a light choice. Or perhaps a HD/Fatbike setup.

I think the BBS02 is good for lightweight 68mm builds. I want to try one on a folder.

[Rix Ryds]

I agree the 750watt unit is perfect for light weight 68mm BB road and folders, anything heavier or used harder I would opt for the 1000w. The N360 is heavy, but you really don't notice it on a ebike. I understand the N380 has better range and is somewhat lighter. The Rohloff is the way to go, if you can afford it, but at $1500, you will likely never see one on my bikes! I'm giving some consideration to a Nexus 3peed on my next build. When using the N360, I noticed I tend to have it in one of three positions, max under drive, max over drive , and unity. Seems a 3 speed IGH hub might be all I need for an ebike, and they are inexpensive!

I guess you do have some impressive range on the Borg, 32Ah, wow! What kind of range do you get if you use only lower pedal assist?

[Alan B]

I haven't done enough low power pedal assist to have an answer, sorry. In a sense, any answer is not very interesting because, depending on the amount of assist the range can be anything.

The Borg is heavy and pedaling it is different. I pedal hard in sprints, to help it accelerate or climb steep hills. I can add 600 watts to it, that's enough to bounce the front wheel off the ground at low to medium speed, but it doesn't stay there long unless the gradient is very steep. I have the power dialed back on that bike to keep the front wheel down. It is a fun bike, a superior commuting machine, but don't run out of juice, it doesn't have enough gears to pedal its weight uphill. This lightweight bike is a lot more practical to pedal. I'll get more data on low PAS settings when I take it on some group rides and we go slower.

The Borg's normal range is about a mile per amp hour when riding hard and fast (like the old commute run with 1200 feet of climbing). Probably closer to a half amp hour per mile if I ever rode it slow and easy. I don't seem to do that much. And that's at 66 volts (18S lipo).

[Alan B]

The right 3 speeds would be great for motoring. The time the in between speeds are going to be most handy is when pedaling is required, either due to low battery or some other issue preventing motor use, or when real exercise is desired. Then the ability to match a desired cadence would be useful.

The Rohloff is interesting, though from what I read shifting with power on doesn't work. Being able to shift when not moving is good on all the IGH's, but they behave differently when power is on. The Rohloff has wider range than a rear cassette, whereas the other choices mostly don't have more range than the cassette they replace. It is pricey, but we were paying more than that for a good battery not long ago, and it will outlast a battery by a long shot. Actually the Rohloff may be a longer term investment than your bikes.

Keeping the project light is a priority than not everyone has. It depends partly on how often carrying the bike will be required. So far I've been able to self propel it when the trail got too steep for riding, so I wasn't bearing the weight of the bike. So maybe a few more pounds wouldn't be a big deal. Most of us could stand to lose more weight than these drives represent.

It would be interesting to try one. I have a three speed hub that came off the BikeE. They made 21 speeds with a 3 speed hub and a 7 speed cogset. Very strange. But that would work with the BBSHD if one wanted full gear combinations. I don't know if it would hold up though.

The one case where this Diamondback is not going to have low enough gears is the steep climbing case with no motor. I've lost about 2:1 on the low end which will make motorless pedaling difficult on steep stuff. The Rohloff could gain most of that lost ratio back if it was setup toward the low end. But there's a tradeoff between buying a Rohloff and building another bike. Priorities...

[Alan B]

Full article on this Diamondback is published: https://www.electricbike.com/a-diy-m...eet-and-trail/

[Rix Ryds]

Nice article Alan. Well Done

[Alan B]

Thanks. It has been a good project.

[Alan B]

I think I'll call this bike the Diamondback "Ridge Runner" after some of the trips I've used it for.

Still need to get the rear brake to stop howling (it's not too bad, but is annoying at some braking levels), and it could use a good washing after the rain stops. The Batt-man is working out fairly well, but I need to get a few more trips on it to gather more data.

[commuter ebikes]

I think I'll call this bike the Diamondback "Ridge Runner" after some of the trips I've used it for.

Still need to get the rear brake to stop howling (it's not too bad, but is annoying at some braking levels), and it could use a good washing after the rain stops. The Batt-man is working out fairly well, but I need to get a few more trips on it to gather more data.

I wonder if it would fix itself after you put a few more hundred miles on it. I was in this exact same situation, meaning to get to a bike shop, and one day the problem was gone. Call it a wearing in period for the rotors.

[Alan B]

It might, but I'll probably try a bit more to see if I can speed it up.

[JPLabs]

Couple thoughts on reducing the disc brake noises....I suspect Alan knows these things already, but may be good info for some:

I follow a 'bedding in' process, which is intended to transfer a layer of brake pad to the disc by getting them hot. Basically, just use the brakes harder and harder a few times when new. Mine have been quiet since new, after doing this. Various methods are used. Detailed info can be found at MTBR forums and similar places with bike knowledge.

For cars, I am in the habit of putting Disc Brake Quiet paste on the rear of pads. This is a damping material which absorbs some of the resonant energy from the pads. It is sticky and can hold dirt, so not ideal for a bike. But might be a useful method if used sparingly.

Next, hardware installation check: Make sure rotor bolt tightening is done in star sequence, and evenly at proper torque. Also make sure caliper bracket alignment is good, and tight. Loosen caliper bolts, apply brakes, tighten under load, check.

I've read that once pads get contaminated with oil, they are ruined and need to be replaced, or will forever be noisy. But others will clean with alcohol and sand off glaze to refresh both pads and rotors, successfully - I'd try that as a last resort.

[Alan B]

Good info, these are new brakes and so fare I've tried readjusting, cleaning and sanding as well as doing some bedding, at this point they're quiet at some braking force levels and not at others. I need to try a few more things including strapping the hoses down, sometimes a resonance can be a problem and loose cables amplify it.

[commuter ebikes]

Good info, these are new brakes and so fare I've tried readjusting, cleaning and sanding as well as doing some bedding, at this point they're quiet at some braking force levels and not at others. I need to try a few more things including strapping the hoses down, sometimes a resonance can be a problem and loose cables amplify it.

The LBS has always adjusted my brakes and made them perfect for about $20.