Thorium's Giant DH Comp Build

[Thorium]

Hello ES Forums, first time posting here, but I'll get straight into business

I've been a long time lurker of these forums and ebike enthusiast and after a lot of beating around the bush I've decided to build my own.
I'm the owner of this beat up old Giant DH Comp, its an earlier iteration of the bike with the 135mm rear swingarm rather than the much more suitable 150mm, but I'll just live with it for now. Prior to endeavouring into ebikes I didn't know a whole lot about bike mechanics in general but I've garnered enough information and knowledge from sifting through countless pages of text to be able to safely throw myself at this challenge, I have chosen to go the path of most resistance and rather than just installing a BBSHD and being "Okay" with it I wanted to build something fast, unique and cool (Yes I am aware DH Comps are a ubiquitous platform for rear hub builds but the average normie will still look at this thing with bewilderment and I'll want to explain to them the inner machinations of my electric turd with pride). That being said this is still going to be largely plug and play (Booooo) with most of the wiring work done by either Crystalyte or Hyena but I'm just a noob so you'll have to forgive me.



To the uninitiated this bike already does LOOK like an ebike, for example one of Paul's battery bags in the frame triangle, the cycle analyst up top and the asymmetric handlebars featuring a half twist grip throttle on the right hand side, and some people seem to turn their heads regardless of it missing a few crucial pieces such as a motor etc. But some kiddies at a shop did ask me if it was an ebike and I just said "Kind of, not yet." Anyway, I have sourced most of my parts from Hyena in Sydney, and the bike is just about ready for assembly, parts include;

[*]Crystalyte TC4065 laced to a 24" wheel, tyres are on the way. (Slow wind because going 100km/h on this thing is a no no)


[*]21S5P Battery pack of Samsung 25Rs with charger (80v, 12.5aH)



This pack was originally designed for use with an adaptto controller and BMS and therefore has the external wires for adaptto's BMS. It was also designed to conveniently fit into the frame of a FUTR Beta (which I will like to own one day). However in this build I will not be using the adpatto but rather the crystalyte controller and I'm led to believe that crown motors are not compatible with adaptto controllers (yet??). As you can see from the photo the cell is quite large and fitting it within the frame triangle of this bike is a no. I have tried a few different angles etc but to no avail so I will likely use a backpack arrangement for it. Paul's battery bag is still extremely useful for carrying my wallet, phone, keys etc. And at the moment it hosts the controller. Speaking thereof...

[*]Crystalyte 72V60A Controller. For use with CA3 (Should make a easy job of wiring).


These are the main cool things, other than the CA3-DP. The other things are less cool. I have some Magura single pot MT4e's for install on the rear but not on the front, looking into upgrading the front brake as well because the Hayes one is on its way out and leaks dot 4 when you press the brakes hard.
Before this thing can be finally assembled I need to obtain a set of Kiwi rear dropout adaptors from Scott. Which shouldn't be too far off. The bike itself is in need of a few upgrades as it still retains the trash tier rear shock (Manitou 6 way swinger) and a trash tier front shock (Manitou Stance Kingpin) which is still quite plush and okay to ride on but massively underspec for what this bike will later be capable of powerwise.

Due to my smaller dropouts and the width of this behemoth motor I will no doubt be forced to use a single speed gearset in conjunction with my 42T front chain ring. I have opted to get a single white industries ENO 18T for the rear but we'll see if that actually comes to be of any use whatsoever.

I also need to wire a BMS to the battery and figure out a charge/discharge solution. I have a suitable charger which you can see next to the battery pictured above. I've been looking at Best Tech Power boards as they are rated at 80A which would be V nice. As far as wiring goes seeing as this cell is made for adaptto it should just be a matter of skipping the -ve of each individual cellgroup OR bridging the -ve of each cellgroup (with the exception of cellgroup 1) to the first positive of the next cellgroup, which would total 21 individual balance leads rather than the 25 I have now. I still need to figure out where I can buy one of these things though. On top of this I need to put connectors on the battery and a whole host of other stuff first. Food for thought.

Thanks for reading & Stay tuned :--)

 

[Rube]

Nice rig Thorium and a solid write up. I hope you have a great time, keep an eye on controller temps if you plan to give it a hiding. How did you source the battery? I have a spare 20s BMS but unfortunately, AFAIK it won't suit your 21s pack. Good luck

 

[Thorium]

Thanks Rube.

The pack was commercially made for use with an adaptto controller (hence the 25 balance leads) and is designed to fit into the frame of a FUTR Beta (hence why it looks like a brick). I purchased it off of Hyena who wasn't using it (I think?) after I decided that a bunch of Turnigy Graphene LiPo's wasn't super convenient for charging say at work, where people would take a dim view if my bike accidentally turned into a LiPo barbecue. I don't plan to keep the controller confined to the bag as I'm aware it will likely get hot. Looking at mounting it externally behind a mudguard or something out of the way.

 

[Thorium]

Got my White industries freewheel in the mail today. Its an 18T ENO. Sticking to a single speed on this bike because its massive motor width paralleled with the 135mm dropouts. Ran into some... issues.


As you can see from the picture its covered in assembly lube (originally I used white lithium grease), same as the actual hub itself. But about 1-2 threads onto the hub it just binds. I've tried to tighten it with my chainwhip and everything but the thing will not thread on. I don't understand, both the hub and the wheel are ISO standard threads of 1.37x24 TPI. Tested it again with an ACS PAWS (Thread type of 1.375x24) I had lying around and it seems to thread on a bit more but still has the same issue of binding every time. The picture below shows the extent to which the freewheel will screw on before it binds. Still plenty of thread underneath it:


At this rate I'm going to see if I can take it to a local machine shop to have the thing looked at because I'm at a loss. In other news my dropout adaptors are crossing the pacific ocean right now so this project is getting pretty close to being driveable. Still looking for BMS hardware and a decent charging setup not to mention a way of rainproofing all my mounted hardware on the bike. Still not long to go.

 

[Rube]

Does the axle nut travel all the way down? Likely to be an issue with machining of the axle flats. Try working the nut up and down with plenty of lube (oh that's awkward). If not there is always room in the tool kit for a thread file or tap and die set. Edit: thinking out loud because I've never added a freewheel to a hub, you might need to pay close attention to to the machined transition on the axle. Preferably, the transition is square similar to a flanged nut.

 

[Thorium]

Perhaps my pictures were a little misleading, the axle itself doesn't come into contact with the freewheel.


You can see the threads for the freewheel under where the axle terminates. It should in theory be a very straightforward screw on process. Clyte states that all of their hubs have a 1.37x24 TPI spot for freewheels. Maybe the threads are a bit "how you going". Also I've been using no shortage of lube, you can see some residual on the threads. ;---)

 

[Rube]

Oh I see that makes sense, could be as simple as over spray from painting. If you don't need a thread file a small pick or similar might be enough to liberate wayward paint.

 

[Wolfeman]

I have chosen to go the path of most resistance and rather than just installing a BBSHD and being "Okay" with it I wanted to build something fast, unique and cool (Yes I am aware DH Comps are a ubiquitous platform for rear hub builds but the average normie will still look at this thing with bewilderment and I'll want to explain to them the inner machinations of my electric turd with pride).

Great writing and good looking build. Looking forward to hearing how that C-lyte motor does with that controller/battery. Thanks for posting.

 

[Thorium]

Thanks for interest Wolfeman.

Bit of an update, dropped the wheel into my local engineering shop to have them look at the threads for the freewheel and my rear dropout adaptors have arrived within Australia. My excitement was stifled when the guys at the machine shop told me it would be like a week before I could have my wheel back but hopefully that's a generous estimate on their part and I can have it back sooner. I wont be able to get the bike together until my tires for the rear hub also gets here. I'm going for some 2.6" wide holy rollers for now, say what you will about them but I got a two for the price of one deal from my bike shop, the only caveat is they had to order them in and its taking forever. More pictures to follow soon.

EDIT: Also looking at beefing up my suspension as well as just fixing the bike up in general. The frame could use a lick of paint and I was thinking I may get it powder-coated in white as I have a mate who does that sorta thing and actually wants to. But more importantly is the state of the rear shock and forks, The forks are okay but I doubt they will be up to the task of handling ebike power. Rear shock is horrid now, starting to feel like a hard-tail. If anyone is familiar with these bikes and can recommend some drop-in upgrades it will be much obliged.

 

[Rube]

Glad more bits are arriving, will it take a week to look at freewheel threads? Seems a while but most good places are busy. Is your problem with the motor thread or freewheel thread? Gl with the fix hopefully you get it back sooner.

 

[Thorium]

White industry freewheels are some of the best you can buy. It's likely an issue with the hubs threads. Like you say the paint over it may have caused the binding. Either that or it's a different thread pitch. Which I'm doubting that's the case. These guys are pretty good though and I sat down with them and explained what it was I was doing etc. They seemed pretty intrigued by it all so maybe that'll spur them into action quicker.

Things are kind of lonely without my hubby though.

EDIT: as soon as I posted this the guys rang me and told me that they finished. Knew they were good but damn. Estimations for a week. Only took 45 mins. Lol.

 

[Rube]

Good news, I'm new to ebikes and looking at a similar frame without shocks or forks. I'm also interested in suspension options, although I haven't searched for specs yet. Do you know the rear shock travel, eye to eye measurements, and fork specs? No need to check if you don't, I should do a bit of research myself.

 

[Thorium]

Sorry I haven't posted recently, life got in the way and my bike has been the last thing on my mind recently as my cars rear sub-frame has crapped its bushes so that's about a 1400 dollar fix, seems expensive but its a Ford Falcon thing.... Had to pull the entire rear subframe and replace the diff hat with one that's a lot more robust and fix all the other assorted junk like trailing arm bushes. Ugh. Writing about it makes me vexed.

Anyway I was going to reply to Rube in regard to my suspension but I'm actually not too sure on the specs of it without searching, I need to have a proper look at my options at some point and hoping I can go to the bike shop in town for that, my bike shop whom I have a bit of a bone to pick as they are yet to deliver my tires and its been over a month however I'm sure its just they've forgotten to ring me or something benign.

I would highly recommend these old DH Comps if you're looking to build one yourself, they are very average as just a pushy on their own because they weigh a lot and the 1x9 gearset makes this thing torturous to pedal on a flat road let alone on a hill, but the dual suspension and the location of the rear shock external to the main bike frame make it an ideal candidate for converting to electric. If you do get one make sure you get a 2003 model as they have the larger 150mm rear dropout swing-arm, making it somewhat easier to accomodate larger motors like a cromotor for example.

Something special arrived in the mail today;


Time to get this big old clyte mounted (I STILL NEED A TIRE THOUGH!!)

More to come soon so stay tuned

EDIT: Realised I should probably say something about Kiwi's Adaptors that I got from Scott in the USA. Special thanks to him if he ever reads this, he was super helpful and a joy to deal with and answered all of my questions. The build quality of the adaptors is awesome, I actually enjoy the raw metal look of them with the burn marks from the welder as it appeals to the "Junker" aesthetic the rest of my bike has at the moment but I'll likely paint them before finalising their installation, perhaps the same colour as the rest of my bike if I get round to pulling it apart and having it powdercoated.

 

[Thorium]

Hello everyone, hope your Easter turned out slightly better than mine. Bit of a thread necro so apologies in advance

Took the bike shop over 3 months to actually finally say that they haven't looked into ordering tyres for me so I decided to not use them anymore and instead bought some online from CRC. They are 2.5" wide Maxxis High Rollers. Probably a little bit undersized for this application but it is whatever. Ideally I wanted to find a set of 3" wide Halos but everyone was sold out of them, likely due to the end of their production run.


Tyre mounted up no problem, took about an hour to get the bugger to sit on there proper. It's not as easy when your wheel weights close to 8kg but sometimes you can use that weight to your advantage to get the bead to sit right (In my experience anyway).

Took today (Good Friday) as a good opportunity to get this thing all fitted up to the bike. In hindsight I should have taken more pictures as well but didn't, probably out of frustration.

Kiwi's dropouts mounted perfectly, absolutely no issue, the picture below only shows the brake side mounted, the chain side however required a bit of motiviation, had to file some paint off of the swingarm to get it to sit in correctly but no issues overall, again testament to the latest itteration of these dropout adaptors, their construction is a masterwork, so Kudos to Scott for that.



This picture shows only the brake side mount attached, didn't managed to snap any images after this so ill just have to explain what happened next....

So with both adaptors in place I go to drop the wheel in place, which at first didn't seem to fit at all due to the overall width of the motor + single speed gear and the brake disk, however after pulling the swingarm apart slightly the motor would sit inside the arm quite snuggly, or so I had thought. The wheel would not sit level and when I ascertained as to why this was the case I noticed that the wheel was offset due to the tyre fouling up against the swingarm. (Area with the red square below)



This prevented the axels from being pushed further down into the adaptors. And its only a 2.5" tyre. At this point I swore very loudly and threw my tools down to have a calming cup of tea and ponder what to do now. The big killer here is the sheer massive width of the crown motor, although it is ABLE to mount in a 135mm swingarm, I would never recommend it to anyone, particularly after this exercise in tedium. So I guess now I have to either get the thing widened or hunt down the uber rare 150mm version off of the DH Team.

Or sell the entire frame and just buy a FUTR Beta.........

Either way its been a pretty miserable Easter. Hope all those reading had a better one.

 

[Thorium]

Fitted up the rear wheel with relative success now, just had to deflate the tyre for it to slide into the dropouts, and a tiny bit of selective filing.

Still having the same issue where the rear tyre is rubbing up against the swing-arm due to its weird geometry. Led to believe dishing the wheel may be able to fix this issue but the offset is pretty massive that dishing alone probably wouldn't fix it, on top of this I'm not super keen on farting around with the spokes in case I accidentally strip the threads on them.

Open to peoples opinions on the matter as I'm not sure what to do from here.

As you can see below, I have almost an inch of space on the brake side of the drive train and no room whatsoever on the chain side.


Its a roller now at least but its been some time since I've been able to go for rides and I'm itching for a few before the winter sets in, might just be the case at this point I sell this and buy a Sur-ron Firefly. They're not so sleeper as what this is but its a better setup all round for offroad/trails etc. And I could probably still use it on a daily commute provided I stay out of peoples way. A Firefly will snap more necks than what I would conventionally like, potentially from the wrong crowd

 

[Simonshift]

Hey nice work overall! I'm looking to build an ebike with bbshd on a dh comp (bcz i prefer to be "okay" :wink: ) and im wandering if the kit fit fine on this bike? I found almost nothing on google about this bike with bbs so i was thiking that it is not compatible... :|
Thx