CYC Stealth Downhill Build - Need Ideas/Advice for Battery

[mikethebikeguy]

Here's the situation:

• I bought a 2019 Intense M16 Aluminum Downhill Bike
• I rode it for awhile as-is; nice bike, but I don't have lift access parks near me
• I recently ordered a CYC Stealth Gen 3 Motor Kit for it (should come in a few weeks from posting)
  • SW102 display (will likely upgrade to 750C Bluetooth)
  • 83mm BB version
  • I got the controller extension wire and mount but not sure where the controller will go yet either.
  • Brake sensors
  • 32T chainring with 53T motor cog
  • Thumb throttle
  • 175mm cranks
• I need a plan for how to power it this beast!

Pictures of donor bike/frame:

Things to keep in mind:

• I ride really hard. I need a battery solution ready for jumps, drops, rock gardens, and general shredding.
• I am shooting for between 15-20ah at 52V. I'm pretty firm on this. It's all I would ever need.
• The bike is mainly for getting to trails and chair-lifting up the mountain for downhills.
• I am focused on maximizing performance for off-road use, I don't care about street performance or local legislation.
• I am open to adding rivets to my frame but not bending, bashing, welding, or cutting my frame in any way.

I am torn between these four options:

1. Using my existing battery backpack
2. Making a new and improved battery backpack
3. Buying some sort of battery pack to fit/mount under the frame
4. Learning how to make my own 18650 or 21700 battery packs from scratch and then making a mount from scratch (sort of like THIS build)

My personal thoughts on the four options:

1. If you look at my last post, I have a jerry rigged Giant Glory 2 with a backpack battery... So I have a backpack battery (52V 15ah) but it's losing a lot of life after four years of shredding (used to output 30A now about 24.4A max [it has Chinese unbranded cells]). I would kind of hate to start with a clapped-out battery on a sweeeet new motor kit. I want to get the most out of my CYC Stealth Gen 3 and I want a more long term solution. It will most certainly be used to test the motor kit before I make a final decision though.
2. It's been four years since my last battery backpack build and I now have a lot more research and knowledge (and some more budget) under my belt so I can make a much nicer one with brand name cells. I would do a hard-shell backpack that hugs my spine and have a 52V battery between 15-20ah. This would also be with an off-the-shelf battery. If I'm making one, it's going on the frame.
3. I am open to this option, and I am open to doing some fabrication to get it on the bike securely. The most I will do to my frame is add some more rivets for mounting my own battery cage. I do not want to bend or bash or cut my frame in any capacity. I deflated the fork and there's just over 3 inches of clearance under the tightest spot near the fork on the downtube to the tire at full compression. I have fully compressed once before riding the bike so I need it to clear at all costs. I will attach some pictures for this option. I cardboard-modeled one battery pack I found and put it on the bike with a cardboard model of the motor.
4. GAHHH WHY IS THE BEST OPTION THE HARDEST! I would really have to weigh the pros and cons to go this route, but it's still on the table if there's no good way to make option 3 work. I am pretty nifty with learning new skills so I'm sure I could fab a battery eventually, but that's a long term goal if it becomes a goal. I would also have to fab a case and mount it to the bike which I would likely do with aluminum so it's stronger and more crash proof than some 3D printed plastic solution.

Have you made it this far? Thanks for reading my post! I am currently leaning towards option 3: fitting a pre-made battery pack under the downtube and most likely fabbing some kind of aluminum cage and aluminum strap or rivets in the frame to keep it really sturdy on the frame for downhill riding.

Here's some pictures of a little modelling I did with an existing Hailong battery pack and the CYC Stealth Gen 3. I used the dimensions provided for the two components and added a little extra distance everywhere for the worst-case scenario. You can find it HERE on Amazon, it's 52V 20ah and triangular.

It's a really cool frame, even though it's heavy as hell, that allows for a lot going on under the downtube. As is, the bike weighs 41.0 lbs with my Stamp 2's mounted. That battery pack is 12.6 lbs, the motor kit installed is 10.0 lbs, and I'm assuming 5 lbs extra for securing the battery pack further. So maybe about 68.5 lbs if I do this exact setup. There's about 0.5" between the tire and battery at full compression which should even allow for some fork flex taking heavy hits. There's room to move the battery a little further down the downtube too (maybe another inch).

More (maybe) helpful pictures:

Some kind of battery that would fit in the striped blue area... but what?

I really am torn between backpack, pre-made under downtube, or custom under downtube. I have enjoyed my backpack battery ebike but I really like riding others where they're part of or on the frame.

I NEED YOUR HELP! Any and all ideas and advice are appreciated. Thanks to everyone that read my post and a special thank you to those who choose to respond. I'll be here to answer any questions and discuss options!

 

[Hardtail]

Your mad, don't change! Have you tested full compression with the rear shock also!? looks like you might have clearance issues when the back has bottomed out also...
I guess you have seen this build? Intense Superbike Definitely one of the best DIY integrations I have seen.
I think you need to spread the battery load out, low is good but not when it is all in one place, make it low and long.
Builds like this are great when you are rubber side down but imagine what will happen during a crash with all of that battery exposed like that.

 

[B1rdie]

I would go for a small sized battery, one that fits inside the triangle, and build two or three modules to carry on a backpack.

 

[Mabman]

That link to that other Intense was my immediate thought. If you can come up with a surround like that for your bike you can send the specs of what will fit in there to herbert@dtbattery and he will hook you up with a good 21700 cell, highly recommended, shrink wrap battery too fit inside.

 

[mikethebikeguy]

So assuming I do go custom (option 4), I have started rendering up some idea of what that would look like on my bike. This may not be the most advanced way to build and attach a battery to my bike, but it is shaped so that I can easily make an aluminum box for it and rivet it to the frame.

Everything is superimposed to scale with a few added millimeters everywhere. I only counted dimensions of the cells and 4mm of aluminum walls so far.
I used the dimensions and weight of the 21700 cells found for sale HERE; 56 of these cells are 8.48 lbs. For the thickness of the case, I assumed I'd use 4mm aluminum sheet metal. I should probably bump the dimensions out everywhere for some shock absorbing foam material and complications wiring/making angles with aluminum, but at least this gives us an idea...
I should add--I plan to relocate the controller to the tiny interior of my frame so it's not hanging down low!

What do y'all think? Any thoughts/ideas? Thanks!

 

[mikethebikeguy]

Your mad, don't change! Have you tested full compression with the rear shock also!? looks like you might have clearance issues when the back has bottomed out also...
I guess you have seen this build? Intense Superbike Definitely one of the best DIY integrations I have seen.
I think you need to spread the battery load out, low is good but not when it is all in one place, make it low and long.
Builds like this are great when you are rubber side down but imagine what will happen during a crash with all of that battery exposed like that.

I don't think there should be any clearance issues with the back slammed? Let me know if I missed the point here xD

Yes I dream about that build every night... It's awesome. He did a lot of things for on-road riding that I wouldn't do though.
(michael.kozera if you're reading this please help--I need your god-tier ebike building skills)

Check out my above post and renders. It will spread out the weight more and I'll build the case out of aluminum. I'd love to hear your thoughts and thanks for the response.

 

[mikethebikeguy]

I would go for a small sized battery, one that fits inside the triangle, and build two or three modules to carry on a backpack.

I would really consider building inside the frame if the triangle wasn't super tiny! I also should've specified that if I don't do a straight up battery packpack, I want all weight off my back (so no extra modules for me). Thanks for your response! I'd love to hear your thoughts on my above post with a rendered plan for another battery.

 

[mikethebikeguy]

That link to that other Intense was my immediate thought. If you can come up with a surround like that for your bike you can send the specs of what will fit in there to herbert@dtbattery and he will hook you up with a good 21700 cell, highly recommended, shrink wrap battery too fit inside.

Check out my above post with a new plan for a custom battery pack. I linked a Samsung battery I've been eyeing too. Let me know what you think. I will definitely shrink wrap if I go custom, I'll do the whole thing by the books. Thanks for the reference, does it get any better than Samsung 50E's? I don't need anymore amps than those put out. Thanks for your response.

 

[Mabman]

I have the 50E's in my 15AH 52v DT battery with a 40A controller and they work really well. I can squeeze 30+ miles out of it riding easy and 25 without limiting my speed and use of the power modes with decent elevation. Problem with heavy bikes is that they are not noted for their long range prowess. But they are fun until the battery takes the v's away.

 

[mikethebikeguy]

More realistic case/spacing...? What color should I paint the case... or camo like the decals?

 

[Bengy22]

What you want to do reminds me of this build in a ebike group on FB (photo is from Seb Dean not me). I think if you have the skills to make sure to properly protect the battery from impacts and you don't mind building your own battery go for it!

 

[mikethebikeguy]

What you want to do reminds me of this build in a ebike group on FB

Thanks for that photo! It reassures me--someone has done practically this exact battery shape and mounting location.

 

[Bengy22]

Thanks for that photo! It reassures me--someone has done practically this exact battery shape and mounting location.

No problem, I've seen it done fairly often with the traditional "shark" batteries and a few times now in a fully custom setup. I would make sure to find a good way to secure it to the bike though, a few rivnuts and straps would be a good setup!

 

[Slowroller]

I bikepack and can tell you that a 70lb bike rides like poo. A reasonable compromise since bikepacking is like backpacking, it's about the experience of traveling and camping in cool places, and it's definitely not about optimizing the riding experience. Your bike, however, is ALL about the riding experience, I'd suggest sticking with a backpack battery and keeping a fun and flickable bike.

 

[mikethebikeguy]

Your bike, however, is ALL about the riding experience, I'd suggest sticking with a backpack battery and keeping a fun and flickable bike.

Thanks for your reply!
I've been thinking about it quite a bit the past few days and talking to people about it/showing my plans and the consensus is starting to lean towards a battery backpack again.

You said "70lb bike rides like poo" and I think about trying to mountain bike with this 90 pound colossal ebike we have and it really does ride like poo on the trail. Then I take my clapped Glory 2 build with the battery backpack and I can shred like I'm on my acoustic enduro bike with a whole horsepower under me...

My opinion on the build today (I know I'm fickle) is to put a lot of effort into a well-done battery backpack.

My battery backpack that I've been using for the past four years was a knock-off camelback I had laying around that the battery I ordered just happened to fit in. It is in no way ideal and there was really no planning done at the time.

This time I want to:

1. Find a durable hard-shell backpack that hugs the spine and does not move while riding hard
2. Make sure it's comfortable while riding hard and does not feel too present on my back
3. Use the the dimensions of the cavity of such a backpack to then seek out and purchase a battery
4. Purchase a snug-fitting 52v 20ah battery with at least a 40A BMS (preferably a 14s4p 21700 cell pack)
5. Make a well-protected cable with a better cable retraction system (my current one breaks often)
6. Shred

I need your help again: recommendations for a hard-shell backpack?

 

[mikethebikeguy]

 

[Dax]

Funnily enough, I bought an intense Uzzi to do a build like this (straight down tube meant I could rotate a bbs-hd quite high) but never figured out the battery. I didn’t want to add that much weight to a back pack and was worried about the risk of injury if I landed on it.

I decided on a custom box on the top tube, then bought a Kenevo before I got around to it

 

[mikethebikeguy]

I didn’t want to add that much weight to a back pack and was worried about the risk of injury if I landed on it.

My current backpack is an 18650 pack 52v 15ah 30A BMS and the pack with battery weighs about 12 lbs.

I have absolutely eaten s*** with my backpack battery multiple times.

First time I slid out on wet grass on a turn and landed on my side and just kind of slid--was completely fine and backpack was fine. Second time I got the front tire caught in a rut between the grass and pavement going ~20mph and smacked down on my right side on the pavement and rolled about 3 full rotations (ow)--I was bruised and cut up but the battery backpack was completely fine. Third time (few months ago) I was at a dirt jump park and I hit a double with about an 8-10 foot gap at probably ~15mph; I cleared it but landed diagonally to the right... smacked down on my right side again on dirt/gravel mix and rolled 3 full rotations again. I was bruised up and down my body--backpack battery was unharmed.

The backpack and battery went unharmed every time.

All three wipe-outs never really hurt my back either, which is great. The backpack has a lot of padding to my back. I am always more worried about the thin layer of fabric between the battery and the open air. My battery is in a plastic case inside the backpack and never has had problems and the fabric has never torn open.

The only scenario I see causing a problem is being thrown off my bike and landing battery-down on a sharp rock.

 

[Blitzkrieg3002]

Good luck getting one in 3 weeks. I was told 3-5 weeks and am just passing the 5 week mark now. Thinking 1-3 months seems more likely the way these guys operate.

Super excited for this build. I'm building an older non boost giant trance up with one. Gonna take my first stab at building my own wheels as well. Good luck on the build!

 

[Marjoriefinnegan]

Brother and I run cyc's. He runs a backpack battery very successfully, but I tried and always felt like it was doing the steering.
The cyc gen3's are brilliant though, you'll really enjoy it

 

[B1rdie]

My diy second battery bag:

 

[mikethebikeguy]

Look what came! Still up in the air about battery solutions… Also not going to mount the motor for about three weeks due to a back injury. Doc says I can’t ride for three weeks and if I mount it I know I won’t be able to resist!!!

 

[mastakilla]

i want to do something like this with an enduro bike. i am not at all interested in a backpack solution and just want to turn a nice enduro bike in to cyc motor ebike. i just want more power than all these low power stock systems deliver that are handicapped by legislation.

 

[Zimmerframe]

i want to do something like this with an enduro bike. i am not at all interested in a backpack solution and just want to turn a nice enduro bike in to cyc motor ebike. i just want more power than all these low power stock systems deliver that are handicapped by legislation.

Rob did quite a funky CYC build - the threads further down in that forum.

DIY CYC Kit Crushes Trek Rail!

And I call it the Black Hawk 😂

www.emtbforums.com

 

[Marjoriefinnegan]

Commencal meta makes a nice donor, can fit cyc and battery in frame.
Eta, found it

 

[mikethebikeguy]

View attachment 117376

Wow that is a clean conversion and very practical. I would have gone for something like that but I have been dead set on getting a downhill bike build going! 200+mm travel front and rear WITH 1500watts?! Maximum send.

 

[Marjoriefinnegan]

Sadly the 200mm bikes are a complete arse to fit motor and battery in
You can over stroke a geometron g1 and get 200mm travel. The x1 will fit in frame but stealth won't unless you modify the mounting arms. Battery however has to fit underneath downtube

 

[mikethebikeguy]

Sadly the 200mm bikes are a complete arse to fit motor and battery in

Hence this thread’s existence! Hahaha

 

[mastakilla]

Commencal meta makes a nice donor, can fit cyc and battery in frame.
Eta, found it
View attachment 117376

that is the cleanest cyc motor setup i have seen on the net. any wobbles of the battery or is secured well enough for hard rocky descents? what is the total weight of the bike? have u had a conventional ebike before that you can compare this build with?

 

[Bengy22]

that is the cleanest cyc motor setup i have seen on the net. any wobbles of the battery or is secured well enough for hard rocky descents? what is the total weight of the bike? have u had a conventional ebike before that you can compare this build with?

Another build I found with the meta, really looks to be a nice frame for a conversion