A DB mountainbike, my 2nd build in progress

I have two light vehicles right now, an unmotorized Milan SL velomobile, and a custom-built electric velomobile on a KMX frame. There has been a small number of times where both were out of commission for brief periods, so I decided to add a third bike to my fleet.

I picked up a used Diamondback on craigslist, which will be receiving my old Phaserunner controller, 1.5kWh Li Ion pack, and Leafbike 1500W 4T motor that used to power my electric velomobile(which has since been upgraded to a 3T wind Leafbike, ASI BAC4000, and a 1.7kWh pack of Molicel P42A). I wanted dual suspension because the potholes around here suck. My expectations aren't high. I'm looking at running perhaps 2kW peak and will use 750W or so most of the time. This build will be much less ambitious than my first, and is going to serve as a back-up bike when all else fails.









I plan to make this able to cruise 25-30-ish mph, maybe top 40 mph(although it wouldn't be safe at speed), and it will probably only get a 40-50 mile range at cruising speed with a stock body.

However, I do intend to increase that range by making a mini bullet faring. See the following moped build for what I've got in mind:


This all said, it appears that my right-side front shock is missing a plastic boot. Does anyone know what they are called and where I can order a replacement? I'd like to keep the rain out.

They're basically just plastic caps; sometimes those for the ends of furniture tubing will fit, and since the tubes on all these cheap forks are typically the same diameter you can pop one off any similar "suspension" fork and try it. If you can find a big enough bottle cork you can use that if you don't mind the weird look.


I used a Diamondback very very much like that one for my Fusin 1000w test bike,
and while the bike itself was alright (as a frame), the suspension it came wiht on the rear sucked. It qualifies for suspension in the same way a pogo stick does.

The suntour fork is not much better; I've used two similar ones, one a little better than the ohter, and they were "ok" with the wavy roads and very small bumps, but actual potholes...not really. They were better than nothing.

I didn't have the suntours when I rode the DB, so I used an old Skareb Manitou with an air leak so it had to be pumped up every ride...but it was pretty good, much better than the Suntours I had later.

I didn't have the brakes that came with the bike, so I don't know how good they are--if they're like the other cheap stuff I've had off cheaper bikes than the DB they are unlikely to be useful at much more than medium pedal-bike speeds. (different pads might fix that, but I don't have experience with that).

The Toecutter said:

I picked up a used Diamondback on craigslist,

Click to expand...

I have a similar DB MTB. Mine is a DBR XR4. I assume the DBR means Diamond Back Race. Mine is identical to this one:




Haven't decided what to do with it yet. I primarily purchased it for the components as It looks in good to excellent condition, but may just clean & tune it for one of the G-kids. - Dunno yet

I had one of those many years ago; it was light weight and fantastic, so it should be enjoyable however you use it.

2old said:

I had one of those many years ago; it was light weight and fantastic, so it should be enjoyable however you use it.

Click to expand...

I rode it back home after purchase. I've never ridden a full suspension mountain bike before, and this was the smoothest upright bike I've ever ridden. I've ridden a lot of uncomfortable punishment devices called road bikes though.

This new(to me) mountain bike still isn't nearly as comfortable as either of my velos, but its smoothness on the roads falls somewhere between the Milan SL and my custom build, the latter soaking up potholes better than many cars I've ridden in.

My main concern with the mountainbike is the durability of its components, more than comfort. Comfort is more than adequate. Will the parts hold up to doing 25 mph on pothole-laden city streets? I will be finding out in the coming months, and hopefully not the hard way.

Today I got my old 4T wind Leafbike motor apart. I needed to make some wiring repairs. The regen use in the trike did damage some phase wire insulation early on when it rocked back and forth in the dropouts and I lost the original cassette-side axle nut. I rode it for nearly 2 years like that and decided to repair it before reusing it. I will be ordering some torque arms and possibly have everything installed before the year is over. Compared to the electric velomobile, this build is quick and simple.

I now have everything installed. I'm about to wire everything up and program the CA3. Maybe go for a ride sometime today.

I had to perform a headset adjustment(first time I ever did so on a bike).

The pedal crank bolts were seized into place. No grease was applied by the manufacturer. Getting them out took hours. I had to be careful not to strip the plastic hex key inserts.

The bottom bracket was seized into place and the non-drive side cup was made of plastic which was heavily degraded and broke upon my attempt to remove it. Getting the existing bottom bracket apart was an 8 hour ordeal, but it was necessary to put the torque sensor in.

The electric motor did not want to cooperate going into the dropouts. Part of the issue was the rear brake. It now rubs and I need to add washers to space it out a bit. The rear brake rotor did not want to leave the rear wheel it came off of, and getting it off was a massive ordeal that stripped a steel hex key insert.

I was only able to use one of my 46.8V 15.6 AH Greenway packs. The panniers I ordered did not fit. I went with a seat-post mount rack to mount a single battery pack instead of both in parallel.

In all, I'm going to start with 750W, and maybe bump that up to 1500W on this single battery pack.

I'll be lucky to get a 20 mile range at 30 mph.

The Toecutter said:

Getting the existing bottom bracket apart was an 8 hour ordeal, but it was necessary to put the torque sensor in.

Click to expand...

isn't consistent with

This build will be much less ambitious than my first, and is going to serve as a back-up bike when all else fails.

Click to expand...

Sounds like a serious case of mission creep. I'm not sure I'd even put a PAS sensor on a backup bike. Less is more in that case.

I have so many spare parts lying around that mission creep is inevitable. I expect this bike to get less than 5% of the total mileage of my fleet.

My first build also had a torque-sensing bottom bracket. The difference being, I installed the initial bottom bracket correctly on my KMX build, and didn't have anywhere near the same difficulty removing it when it came time to put the Sempu torque-sensing bottom bracket in its place.

I pedal my bikes to extend range, so I want some sort of PAS. I did order a Grin cadence sensor for this project, but it didn't fit the crankset the mountainbike came with, so I pulled out one of two torque sensing BBs I had laying around, and it fits.

I didn't think torque sensor installation was a complicated thing in the ebike world.

This mountainbike build literally will be ridable with less than 1/10th the time invested compared to the flimsy kayak of death(soon to be the 100+ mph AWD not-as-flimsy kayak of death). Including repairs/partial restoration/adjustments/component swaps, I have about 25 hours in the mountainbike thus far. Another 2 or 3 and it will be riding, hopefully.

I am going to order a twist grip throttle for it as well. I'd rather have a throttle and not need it, than need it and not have it. I could add that with less than an hour of work when it arrives. If the PAS ever craps out, it will be as simple as disconnecting it from the CA3 and using the throttle instead, and/or pedaling it.

Eventually, I'm going to relocate the controller out of that small triangle part of the frame and custom spot-weld together a 72V battery pack that will fit inside, and delete the rear rack. I also will eventually make a wheel disc cover for the rear wheel. Adding a front fairing will be necessary for better aero, while side fairings will hide all the wiring and batteries.

The Toecutter said:

The pedal crank bolts were seized into place. No grease was applied by the manufacturer. Getting them out took hours. I had to be careful not to strip the plastic hex key inserts...

The bottom bracket was seized into place and the non-drive side cup was made of plastic which was heavily degraded and broke upon my attempt to remove it. Getting the existing bottom bracket apart was an 8 hour ordeal, but it was necessary to put the torque sensor in...

The rear brake rotor did not want to leave the rear wheel it came off of, and getting it off was a massive ordeal that stripped a steel hex key insert.

Click to expand...

This certainly sounds suspiciously like the frustrations encountered with a BSO type bike. Thought the DB was supposed to be several levels above that?

99t4 said:

This certainly sounds suspiciously like the frustrations encountered with a BSO type bike. Thought the DB was supposed to be several levels above that?

Click to expand...

There's a sticker on the bottom of the downtube that the seat post slides into that proudly says "MADE IN CHINA".

This particular model had a frame recall and the frame on this bike is new as a result.

Looks like we are both building an upright backup bike soon

The Toecutter said:

However, I do intend to increase that range by making a mini bullet faring. See the following moped build for what I've got in mind:

Click to expand...

I'm pretty interested in hearing about this part.
I'm considering one of these units since i can't fabricate much at this time: Title
Curious how much of a difference something like this makes on an upright.

The Toecutter said:

My main concern with the mountainbike is the durability of its components, more than comfort. Comfort is more than adequate. Will the parts hold up to doing 25 mph on pothole-laden city streets? I will be finding out in the coming months, and hopefully not the hard way.

Click to expand...

You'd be surprised. That 6kw leafbike dual suspension i built just ate up the potholes like it was nothing at 40mph and beyond. I had some nice suspension components on it though ( oil/air fork, fox shock in the rear )

This particular model had a frame recall and the frame on this bike is new as a result.

Click to expand...

Ok, nevermind, keep it below 30

neptronix said:

You'd be surprised. That 6kw leafbike dual suspension i built just ate up the potholes like it was nothing at 40mph and beyond. I had some nice suspension components on it though ( oil/air fork, fox shock in the rear )



Ok, nevermind, keep it below 30

Click to expand...

I'm not confident this thing could handle 40 mph on bad roads. I have a cheap Suntour Sr. fork up front and a coil shock for the rear. On known roads that don't have bad potholes I think it could do it, but I have mechanical disc brakes and probably wouldn't want to on a regular basis.

Maximum planned cruising speed will be 25-30 mph. A properly designed set of fairings could increase range 30% or more at speed.

The frame mine has is the stronger replacement version without the defect. It IS aluminum though. I tried to find a used steel dual-suspension bike in my local area to no avail. Everything is either aluminum or carbon fiber now... including and especially so the high-end stuff. What sold me on this one was that it still used 7-speed components, which are nearly ubiquitous in the ebike world and which I had parts for.

neptronix said:

I'm pretty interested in hearing about this part.
I'm considering one of these units since i can't fabricate much at this time: Title
Curious how much of a difference something like this makes on an upright.

Click to expand...

Which model are you considering? I ran the AM-ZZIPPER on my Moulton for a few years, and something similar to the ZZ-THRILLER on my Bridgestone MB-3 (nonsuspended) MTB.

It now works.

I might have to delete the rear disc brake caliper though. The spare Avid BB7 I have does not fit with the mounting point on this bike, and the caliper it came with has a fixed location semimetallic pad on the left side which slightly rubs on the rotor. There isn't much I can do about this given the position of the Leafbike motor. I'm going to have light regen in the rear anyway.

Another possibility is I just lathe away part of the pad while riding the bike until the rotor clears.

In any event, I need to do some research to find brake calipers that will fit this frame and upgrade. The calipers that are on it are kind of crap.

I also need to find some kind of on/off switch. I'm using the battery plug for that at the moment.

I wouldn't trust your seat post with that battery(?) hanging off the back.

nicobie said:

I wouldn't trust your seat post with that battery(?) hanging off the back.

Click to expand...

I don't trust it either. It's a temporary measure. The cheap rack is rated for 20 lbs. I have a 9.5 lb battery on it at the moment.

I'm eventually going to spot weld a custom 72V/2kW/750Wh-ish battery to fit into the tiny triangle part of the frame and move the Phaserunner to the top tube up at the front.

The Toecutter said:

I don't trust it either. It's a temporary measure. The cheap rack is rated for 20 lbs. I have a 9.5 lb battery on it at the moment.

Click to expand...

Pretty sure they "rate" almost all racks only just sitting there with the weight on them.

I doubt anything that doesn't give testing specifications (whcih I have yet to see on any rack) regarding weight at specific impact and vibration g-forces and cycle rates would actually hold what it's "rated" for under much beyond smooth pavement...and many racks I've used or worked on for others can't handle the lateral wag caused by cycle pedalling, with much of a load on them near the rear end--their mounts fail or disassemble....

The Toecutter said:

I might have to delete the rear disc brake caliper though. The spare Avid BB7 I have does not fit with the mounting point on this bike, and the caliper it came with has a fixed location semimetallic pad on the left side which slightly rubs on the rotor. There isn't much I can do about this given the position of the Leafbike motor. I'm going to have light regen in the rear anyway.

Another possibility is I just lathe away part of the pad while riding the bike until the rotor clears.

In any event, I need to do some research to find brake calipers that will fit this frame and upgrade. The calipers that are on it are kind of crap.

Click to expand...

Sorry can't quite tell from the grainy photo but I solved my rear caliper interference by installing a 203mm rotor and appropriate caliper mount adapter.

I'm ordering some replacement bearings for this motor. Soon after I started riding it, the mechanical resistance in the motor went from un-noticable to unridable. I have bad bearings in my motor, which isn't exactly a surprise since it has over 20k miles on it from use in my velo and has ben ridden in all weather conditions found where I live(including snow/salt).

At some point in the future, I'd be tempted to order a front Leafbike motor as well to make this thing 2WD.

I'm also ordering racks appropriate for storing the battery, which mount to the rear swingarm and front post respectively. That $20 rear rack is junk and I could feel it trying to shake itself loose when I rode it, which isn't exactly desirable at 25+ mph...

The Toecutter said:

I'm ordering some replacement bearings for this motor.

Click to expand...

So, I assume you managed to ID the bearings?... hopefully. If the bearing seals are unreadable, you'll need to resort to a set of calipers to measure OD, ID, and width. Be advised, not unlike nearly everything else, there's a frightening array of cheap counterfeits.

Papa said:

So, I assume you managed to ID the bearings?... hopefully. If the bearing seals are unreadable, you'll need to resort to a set of calipers to measure OD, ID, and width. Be advised, not unlike nearly everything else, there's a frightening array of cheap counterfeits.

Click to expand...

I was able to clearly read them, fortunately.

They were labelled as 6902 RS on the drive side of the aluminum case plate. The bearings inside the cassette freehub are the smaller 6901 RS.

I have a new, never laced G62 from Grin, scattered across my bench. Four bearings... one that rotates like it has sand in it. All four bearings are being replaced.

Papa said:

I have a new, never laced G62 from Grin, scattered across my bench. Four bearings... one that rotates like it has sand in it. All four bearings are being replaced.

Click to expand...

Quality control on those things isn't very good it seems...

Hopefully the replacements are in good working order.