Trek Fuel - Small block left drive first build

[the_nitro_addic]

Hello,

Starting to build my first ebike, with my trek fuel Mtn bike with a LTR small block setup to drive on the left side. Planning to use a FOC controller (40 -80 amp range) that I can program and drive it with rc lipo 18s pack. Looking for some recommends for good performing throttles and possible bluetooth interfaces for displays and programing if available within budgets. Hoping to set it up with a current throttle. Its my first build but I have a few years of ebike experience and have help from my gramps who has built a few so far and helped me narrow down some of the options and has a shop and can show me how to build some of the custom components needed. Any help welcome.

Thanks, Gabe

 

[Chalo]

That's a disc brake only bike, right? How you gonna reconcile that with left side drive?

 

[the_nitro_addic]

That's a disc brake only bike, right? How you gonna reconcile that with left side drive?

Yes, disc brakes front and rear. I am going to have to find a rear brake with a smaller caliper in order for the sprocket to fit. I have not sorted that part out yet.

 

[markz]

Go for some heavy duty regen braking if its a rear hub or braze on some v-brake mounts.

Heres a contraption, what the bicycle gas people do I guess
https://www.bicycledesigner.com/motorized-rear-wheel-disc-brake-kit.html

Though I was searching more for something like this
https://youtu.be/TOIefF80Lzs?t=379

This came up on search term via images.
I wonder how much space there is between the chain and the disc rotor. Chain oil flung onto the rotor will mess up brake pads quickly so not a good combo.
https://www.bikeforums.net/singlespeed-fixed-gear/494857-left-hand-drive-disc-brake-print.html

 

[Chalo]

Chain oil flung onto the rotor will mess up brake pads quickly so not a good combo.

Hey, you can always run the chain bone dry, right?

Seems like what most of the fixie riders in my neighborhood were doing ten years ago. You could hear them squeaking before you saw them.

 

[speedmd]

Wax! ? Certainly not a place for mobile oils.

I am designing a dual mount hub now for a 92 tooth 219 sprocket, and 160mm rotor. Need roughly .7 inch spacing to clear most calipers I have checked. Need to make sure spoke and tire clearances are suitable.

A few builds have done this so far and in use.

 

[speedmd]

Here is a LTR build that was on FB. Looks to clear well.

 

[Grantmac]

Could the smallest available brake rotor fit inside the mounting plane of the sprocket? You won't need a lot of braking force if you use regen to do most of the work then modulate with friction brakes.

 

[speedmd]

Could the smallest available brake rotor fit inside the mounting plane of the sprocket? You won't need a lot of braking force if you use regen to do most of the work then modulate with friction brakes.

I believe you can. You still need to pocket out the center of the sprocket hub to clear the caliper. There is enough room to have them sit side by side unless you go to wider tire on std mtn hub. Idea Reminds me of my old moto setup.

If you're not dedicated to regen or wanting a freewheeling motor, you could set up two single speed freewheels on the freehub and keep both chains on the opposite side of the wheel from the disc. One would allow motor to drive or not independent of rider effort On the second freewheel. They are available from the trials guys.

 

[Grantmac]

I'm not a huge fan of running two chains on the right but it is an option. Especially if you could mount the motor sprocket directly to the hub. It wouldn't let you build tep reduction stages for the motor very easily though which I think is important if any real climbing is the goal.

You could also look at the belt system that LMX is using on their dual drive bike. Its easier to offset a belt pulley and of course it doesn't need lube.

 

[speedmd]

LMX was running something very much like I am building. Mine will be both a floating type disc and sprocket mounted to a hub suitable to accept 5.25 BC kart sprockets and common Avid disc that has been removed from its hub. Belt does have a bit of latitude on chain line.
Agree that the solid mounted sprocket allows much more power and potential throttle control with slide braking and regen. More a issue if it dies and your miles from home.
from the LMX -64 thread showing a full size disc mounted to a kart adapter. Not found the dual belt

 

[the_nitro_addic]

I am building my first e bike on a trek fuel; small block left drive with sabvoton controller. I am looking for some good throttle recommendations, which is one of the components I have not chosen yet. If anybody knows some good throttles out there please respond

 

[speedmd]

There are many threads on throttle choices. Do a google search of the site to best find them. If your add a CA (Cycle analyst) you will have some control over throttle ramps which help greatly.

I have a sabvoton 72150 on my GNG 450. Much like the small block with surface mount magnets. It has never run or been setup fully. It runs, but I gave up trying to fix all the issues. Most likely just need to add the correct hall sensors in the motor to get it to see them reliably. The supplier tried to help, but I ran out of time and patience with it. Hope you have better luck. Once it self learns and runs a few minutes it does run incredibly strong. Much too much power for a bicycle chain. Kart chain will be a big benefit.

I also was not able to get the CA working with it. With the hall test fail I went no further. No issues setting up the CA on a standard 18fet controller. Be ready to dig in a bit on it. The Phaserunner IMO is a better size controller for something like the small block. I would check with Grin on their experience getting it setup for one. I remember some folks having issues early on with some mid drives. Would be a big benefit IMO for a first time builder to have that type of support getting it up and running. What ever you end up with, unless you have some help, get a controller with "self learn". Getting the hall -phase order correct is critical and not always easy to make sure is correct.

 

[speedmd]

Got a left side brake - sprocket hub prototype turned up and fit. Started with a 6" round 1" thick billet which was a bit wider than needed, but I needed to explore the envelope limits so it was a good starting point.

The 1 inch thick hub is doable, but, I am needing to minimize the sprocket mounting hardware protrusions and bend in a few high spokes, and possibly limit tire width to something more like a 1.95" to avoid some slight chain rub or move out the brake assembly slightly on a standard mtn bike rear. If you go 1 inch thick, IMO it would be good for a wider fat bike hub -rear spacing. It does look like it will work reliably and should handle motorcycle power if the hub brake mounts can handle it. I have a 3/4" thick x 6" round billet on the lathe now that I may try next if time avails to see if I can get it to clear with less interference on a standard Mtn bike rear and not fight too little caliper clearance. Should work if I minimize the centering shoulders for the sprocket and rotor going by some quick deciphering.

 

[thepronghorn]

My take on fitting a disc brake and sprocket on the left side:

https://endless-sphere.com/forums/viewtopic.php?f=28&t=110034#p1611856

 

[speedmd]

Thanks for sharing the link. Most definite, a great way to go on large spiders and sprockets. Heavier Brake rotors cut to share sprocket mount hardware would be trick. Higher kv motors need much larger sprockets than what can be commonly found in kart chain options. What chain are you running.

 

[speedmd]

I will need to move the caliper out a few MM and cut out a bunch of extra material and paint it, but it fits.

 

[Chalo]

Did you make a decision on dry chain vs. greasy rotor?

 

[speedmd]

Wax only! Greeeasseeey bike mechanics not allowed anywhere near it. LOL. Lots of moto chain o-ring type dry lubes avail. that will work also. The setup was used for years on them.

 

[Chalo]

Seems like wax particles would also do a great job lubricating your rotor and pads. Please keep us posted with results.

 

[thepronghorn]

Thanks for sharing the link. Most definite, a great way to go on large spiders and sprockets. Heavier Brake rotors cut to share sprocket mount hardware would be trick. Higher kv motors need much larger sprockets than what can be commonly found in kart chain options. What chain are you running.

I'm running #25 chain which fits onto 1/8" aluminum pretty well. I beveled the tips of the teeth a bit by spinning the sprocket against a file. No problems with greasing my rotor or pads so far. It might help that my sprocket is larger diameter than my rotor so oil gets flung away from the rotor.

 

[speedmd]

Not at all worried about rotor getting soiled. Certainly a good point to use caution on chain lube choices. The dry film-forming foaming moto chain lubes should be perfect for the 219 chain. Care certainly to make sure overspray aims away from the rotor as one has to do now with them not getting all over clean painted surfaces in the sprays wake. Worst case, a chain guard could be added to the sprocket as another barrier. Belt is also a option long term.

I'm running #25 chain

Was thinking of 25H for my small block size setup with a left side direct drive. Using 25 on the primary side of the old GNG and you can pack a bunch of teeth on a small size sprocket with it allowing much higher reduction ratios. Nice and compact also. How far apart did your sprocket and rotor end up. Mine is around 22mm, leaving a few extra mm to clear caliper. Still may be possible to set the rotor a bit deeper (into slight C-bores) and not move the caliper at all. Looking like 3/4 thick hub may just work with calipers that are compact on the back side as are some of the shimano ones I noticed were.

 

[thepronghorn]

....

Was thinking of 25H for my small block size setup with a left side direct drive. Using 25 on the primary side of the old GNG and you can pack a bunch of teeth on a small size sprocket with it allowing much higher reduction ratios. Nice and compact also. How far apart did your sprocket and rotor end up. Mine is around 22mm, leaving a few extra mm to clear caliper. Still may be possible to set the rotor a bit deeper (into slight C-bores) and not move the caliper at all. Looking like 3/4 thick hub may just work with calipers that are compact on the back side as are some of the shimano ones I noticed were.

I have about 12mm between the sprocket and rotor. Since the sprocket fits around the caliper, I have it spaced away from the hub centerline for tire clearance, so there is 18mm of clearance for the caliper.

 

[speedmd]

18mm will not clear one of my calipers. 3/4 stock should work for most with a bit of caliper move. Still looking for stock 2pc rotors with rivet circle diameters to match or be made to match stock sprocket BC.

Nice spacing the tooth ring of the large sprocket outboard. Clever solution to the tire clearance issue. The Kart sprockets I have been playing with are thick (close to 5mm) and can be thinned a few mm in the caliper area allowing a bit more tire clearance and less offset. The added benefits from regen, improved throttle control, and having a super strong chain are worth doing some more study.