The Golden Goose. 72v Dengfu E55 CYC X1 Pro.

[bram.biesiekierski]

Got out for another ride today. Damn this bike is fast!! Did a section of single track that i know very well. Beat my e22 PBs with ease. Obviously power is a big factor here, but the bike still needs to get around the features/corners and it does this bloody well aswell.

The bike is surpisingly easy to manouver. Before completing this build i honestly wasnt expecting it to be as nimble / easy to throw around as it is. I was expecting more acceleration / speed, with a negative tradeoff being less agility / manouverability. But im not really experiencing any negatives. Im thinking its the high front end, it just gives great confidence, the high riding position gives a great platform to push the front through the bends. Leaning the bike is easy, and it pendulums side to side very well. I dont know what it is, but i reckon its better than the e22 was.

Managed to get the rear brakes less grabby by adjusting the lever ratio. Its now feeling pretty bloody good.

I got the suspension in the ball park. Still not perfect, but i reckon its better than yesterday.

I had a hard pedal strike with a tree or rock and bent the crap out of a crank. The X1 100mm has realy wide Q factor, and it just doesnt fit through tight gaps that well. Although ive bent 3 cranks on the e22 before, so i cant blame the X1 too much. I buy my cranks in bulk for this exact reason. I was just hoping it would last more than 1 ride. On the bright side. The crank bent before the 3d printed bracket gave up.

I also dropped the chain twice. And the second time it wedged in between the side plate of the X1 and the chainring spider. The chain basically chainsawed into metal and gouged it pretty bad. The metal shavings forced into the rivets on the chain, and bent a few chain side plates. The chain didnt snap though. But it is scrap now, some of the links ate so much metal, they wont bend anymore. So im going to have to figure out a chain guide system somehow.

It feels like 1 step forwards, 2 steps back.

 

[bram.biesiekierski]

Here is a close up of the damage from the chain drop. The side plate has some pretty bad gouging. I dont think its structural yet, just cosetic. The freehuab/torque sensor also has some minor cosmetic damage.

The 4 bolts that secure the chain ring group to the freehub also siezed up and were impossible to remove. I had to grind 2 of them off. So they are another issue.

The chain is also scrap. It has bent plates, and siezed up some links. I have a bunch of spare KMC E9 Turbo chains. But it is dissapointing to have to replace it so soon.

Even the steel chainring itself has some signs of wear. The leading edges of the teeth have some visible indentation / mushrooming already. I was hoping to fit a larger chainring, but there is no narrow wide steel 104BCD 1x chainrings on the market above 40t that i can find. They just dont exist. There is alloy versions, which will be too soft. There are steel 2x systems, but they dont have narrow wide tooth profile. The reason i want to fit a slightly larger chainring is to overcome the ghost pedalling feeling you get at high trail speeds.

The rear CYC cassette still looks brand new, so I suspect the metal they use there is higher grade than the metal used in the front chain ring. Like an actual heat treated cro-mo variant.

I have contacted CYC to see if there is anything theu can do. I also placed an order for some more spares. Things like a couple of additional chain ring groups. Spare front chain, spare chain tensioner, spare throttle, spare speed sensor, spare display. I want to basically have the parts on hand to fix and maintain this kit, rather than wait when i need them.

As for the chain dropping issue, i am considering trying to attach a chain guide to lead the chain into the chain ring. Aswell as possibly just sandwhiching additional chain guide discs onto the chainring assembly stack. This has worked perfectly for me on the E22, as once i did that, i have never dropped a chain.

 

[kaaskopf]

which derailleur are u using ? lots of power here

 

[TQFreak]

Innotrace X1 controller at 3000W mishrooms steel chainring too withing some time. Those widened chainring teeth can start damaging the chain and cause chain failure. I just grind the mishrooms sides down with Dremel to get more life out of the chainring when those mishrooms become too wide. The mishrooms on your chainring do not look bad yet though.

 

[bram.biesiekierski]

which derailleur are u using ? lots of power here

Im using the derailer that comes in the CYC 5spd HD kit. Its a MicroShift 9spd unit that you adjust the limit screws to make into a 5spd.

It is something Im already a little concerend with as far as chain tension. It shifts fine. But the spring / clutch system has a fair bit of backlash before it even begins acting on the chain, and the spring itself doesnt feel that strong.

The KMC e9 turbo chain is a chunky unit and has a bit of weight in it, which is probably more than the derailer was designed for.

 

[bram.biesiekierski]

Innotrace X1 controller at 3000W mishrooms steel chainring too withing some time. Those widened chainring teeth can start damaging the chain and cause chain failure. I just grind the mishrooms sides down with Dremel to get more life out of the chainring when those mishrooms become too wide. The mishrooms on your chainring do not look bad yet though.

OK. Yes i dont think they are that bad yet either, but thats after just 2 rides. Maybe 30km total. Good tip about deburring the edges as they mushroom out. On the e22 / bafang ultra, i never had that kind of wear even after alot of KMs.

Its weird though, because that is the chainring supplied by CYC on the X1. The CYC 5spd cassette doesnt have any wear yet, and the 3rd, 4th, 5th gears which is what you use the most are all smaller tooth count. So you would expect them to wear faster. Im certain the metal used in the 5spd casserte is far superior to the metal used in the chain ring. I wouldnt be surprised if the chain ring isnt actually made by CYC, rather just a generic item they sourced elsewhere.

 

[bram.biesiekierski]

I have ordered a few bits and pieces to get the driveline sorted once and for all. I ordered some Bafang M620 42t chain ring kits. The standard M620 spider is 5 bolt so wont work directly with the CYC 4 bolt system. But im pretty confident I can put them in the lathe and bore out the inside, and then weld onto a 4 bolt chainring with the teeth and outer edge turned down to match.

I also found a 44t m620 chainring kit that has the 4 bolt spider, i suspect not Bafang OEM parts. I dont know about the quality, but that may be a direct swap onto the CYC.

My plan is now to use additional chain guide discs on either side of the chain ring to direct the chain in. I have a few different sizes of these discs coming, and a few different sizes of spacers etc to make it work. Im pretty cetain there is enough space between the CYC spider and side plate to accommodate the additional guide discs. As i mentioned earlier, this has worked perfectly on the e22, never dropped a chain since doing it, and that bike has been through some rough stuff.

The challenge with the guide disc approach is that the entire stack becomes extremely thick. The CYC system is already very thick as standard with the reduction chain and the conventional chain etc. Adding a guide disc and spacer will add atleast 5-6mm minimum. And those special chainring bolts are already longer than any i have seen. Due to how bad they jammed upwhen I pulled it down, I want to have a hex head at either end of the bolt, instead of the standard slotted head. So my idea here is to cut the slotted end off right away, making the nut part a tube. Then screw a hex head bolt in from either end. By modifing the CYC bolts like that, i will be able to increase the stack up length, and avoid another nightmare next time i tear it down.

 

[bram.biesiekierski]

I was messing with the bike the other day and noticed my seat rails bent somehow. Maybe i need to go on a diet? I tried to re-clamp it to the seat post and pull it straight but it didnt make much difference.

 

[Tumid1]

If anybody's interested in a similar project I have a brand new e55 frame sitting in my garage. Which I have bought for a similar purpose but later dropped the idea. Will be willing to sell it cheap if anyone is interested.

If you still have it please PM me

 

[bram.biesiekierski]

I think I have a solution for the dropped chain / lack of chain guide issues with the CYC X1 system. My idea should also address the ability to fit decent quality, larger than 40t, steel, narrow wide chainrings to the system. As I also find the 40t too small when paired with the CYC 5spd driveline.

I have designed a 104 BCD to 130 BCD adapter. Which is getting manufactured as we speak. The adapter will allow standard Bafang Ultra 40t / 42t / 44t chainrings to fit onto the CYC X1 motor freehub. Aswell as sandwich on some standard Bafang Ultra chain guards to the assembly, to prevent the chain dropping. The design doesnt add any additional thickness to the 104 BCD mounting bolt sandwhich. So standard CYC bolts can be used. (I plan to modify the CYC bolts with hex heads at each end to aid in future removal.)

The part is currently getting CNC manufactured out of 7075, with blasting and gold anodizing. Not that I care about weight, but it weighs less than 50 grams.

The Bafang 130 BCD chainrings / chainguards should fit perfectly, except for having to slightly chamfer these 2 x corners down. Unfortuantly there was no other way to make it all fit due to how close 104 and 130 BCD patterns are. But that will take 20 seconds with a grinder/file and wont make any structural difference.

It sounds kind of ridiculous, but 42t or 44t should be a pretty good match for the CYC X1 / 5spd combo. Im not upsizing the chainrings for more top end speed. The standard CYC 40t / 5spd can do about 85-90 KmH. That is plenty fast. (Although with a larger chainring, the bike may be able to achieve 100kmh. )

The reason I want larger chain rings is because my legs cant keep up at fast trail speed. You get this ghost pedalling sensation, where the motor can go faster than your legs, and that feels horrible. By slightly up sizing the chainrings, it will allow my legs to still pedal at fast trail speed, without the ghost pedal sensation. I get a similar feeling on my e22 with the CYC 5spd drivetrain aswell.

THe CYC 5 spd cassettes fastest cog is 15t, which means that when coupled with a 44t chainring it is basically pretty similar ratio to a 32t or 34t chainring on a standard sram/shimano 12spd. That is because those 12spds have alot smaller fastest cog. Due to the CYC having a larger fastest cog, you need to increase the chainring in order to achieve similar ratios.

 

[bram.biesiekierski]

I have fitted up some chain guide discs to the bike. Still using the standard CYC, 40t, 104BCD chain ring. This is a temporary measure while i wait for the 104 to 130 adapter to arrive so I can try the Bafang 42t / 44t chainrings. Just a proof of concept to see if the chain rings can sufficiently retain the chain. And if there is sufficient clearance to fit the stack up. So far no dropped chains.

 

[bram.biesiekierski]

I had a silly crash aswell yesterday, which resulted in a trip to the ED and some stiches. I wasnt even going fast. Just climbing an uphill switchback, hung up on a rock and flopped over sideways. Just a dumb fall. My knee landed right on a rock and split open. A small gash, but alot of blood. But weirdly, a weird worm like piece of flesh was protuding from the wound. It literally looked like an earthworm about 20-30mm hanging out of me. I was comcerned this could be a ligiment or tendon type of flesh.

Unfortuantly, i was about 8kms from the car, and the rear wheel valve stem completely snapped off, leaving me stuck with a flat, and long slow hike out of the hills. I trekked back, loaded up and went home. A quick shower, dress the wound and into hospital.

They X-ray me, no fractures. Then they put some local numbing injections, flushed the wound with saline, cut off the worm like flesh, and stitched me up. The doctor confirmed the flesh piece was subcutaceous fat that had been torn and pulled out the wound.

The bike is fine apart from the valve stem.

 

[kaaskopf]

ouch! hope you feel better soon

 

[bram.biesiekierski]

ouch! hope you feel better soon

Weirdly, it doesnt actually hurt that much. A little tender but otherwise ok

 

[bram.biesiekierski]

My 104 to 130 adapter arrived from JLCCNC the other day. The chainrings fit into it perfectly, the fit clicks into place with just fingur pressure, and is snug enough to stay clicked together. The color is 'champaign', which sounded like the closest off the shelf color to gold. But it just doesnt match the rest of the bikes gold highlights.

Unfortuantly, i cannot get it into place on the CYC spider. Atleast not without removing the spider from the crankshaft. The adpater inside diameter will go over the lugs with some tetris. But the adapter is too thick at the area where the lugs meet the spider. It wont clear these bulges on the CYC part. I could probably make it fit with a grinder, but it would be nice to not have too.

I repaired the valve stem. Also had to true the rim, as the spoke closest to the valve also hit whatever it was that snapped the valve off. It wasnt broken, but it was quite loose. It will be one to keep an eye one. As these Sapim Strongs are pretty meaty spokes. Ive used them on quite a few rim builds now, and ive never had one stretch that much. I will have to get another gold cap. Might look around where i crashed and see if its still there.

This is how Ive modified the CYC bolts. Ive turned the flange off the "nut" part, and then used a bolt at eirther end of it. That way I can use a hex to undo and not worry about the crappy standard slots chewing out.

 

[bram.biesiekierski]

I have designed the V2 104 to 130 BCD adapter. This one incorporates a chain guide and spacers. Saving on assembly complexity. It has larger internal clearances to fit over the CYC 104 spider. I also tried to give it a futuristic organic look with alot of complex radius curves. I spent a bit of time trying to optomise the design and remove a lot of non critical material. I even got the theoretical CoG to within 0.5mm of the axis of rotation. Im going to do some final measurements to try and confirm fitment before sending for manufacture.

 

[bram.biesiekierski]

I got a PLA print from a friend to check fitment. You can see the gold part below which is the V1 adapter. A fair bit more internal clearance. The chain ring behind is a 42t Bafang for size comparison.

This picture shows with a Deckas 44t chainring behind. The chain guide is the exact same diameter as the CYC bash ring, so wont protude any further than that. And still sits above the 44t chain line, so should still guide the cahin in as intended.

The red circles highlight the area that caused the fitment issues with the V1. As you see these are now partially notched to slip past the bulges in the CYC torque sensor.

 

[kaaskopf]

how fast do u want to go ?
big chainrings!

 

[bram.biesiekierski]

how fast do u want to go ?
big chainrings!

Its not about top speed. Its about gear ratio / pedal cadence.

Remember, the CYC 5spd cassette smallest cog is 15t. A typical 1x MTB 12spd smallest cog is about 10t these days. (10t or 11t depending on which feeehub driver / cassette brand you use.)

A 30t chainring with a 10T rear cog is EQUAL to a 45t chainring with a 15t rear cog. They are both a 1:3 ratio. So that means a 44t chainring on a CYC 5spd actually has a lower gear rario (top speed) than a 30t chainring on a modern 12spd. A 30t chainring on a 12spd is very small, even on an anolouge MTB I like to use larger like atleast a 32t.

When you think about it like that, 44t isnt actually very big (physically big yes, but not a big gear ratio.). It just sounds big when your thinking about things on a more conventional MTB.

The CYC X1 motor can spin alot faster than my legs, (this is what allows the motor to use the high power output, without totoally shredding the gears instanrly. Remember, power = torque x RPM.) The human leg is the opposite, it can push with high force, but cannot pedal at a particularily high RPM. The downside to this mismatch on a hybrid system is you cannot satisfy both sides.

On a CYC system, this can result in a sensation called ghost pedalling. Where the motor is going so fast that your legs cannot add anything, and are just free spinning. All i want to do is extend the onset of this ghost pedalling a little higher. A little higher, and then i wont feel it on the trail at the speeds i typically ride.

The other effect is that the bike will have a higher absolute top speed. Currently its around 85/90kmh. With the larger chainring, it will probably achieve 100kph. But that isnt my motivation. I cannot ride anywhere near 100kph offroad, and this bike is built purely for offroad.

 

[bram.biesiekierski]

Bikes running good. Really getting the feel for this thing now. Its insanely fast, and really gets the adrenilin pumping. Great fun to ride. I feel it kind of falls somewhere between an eMTB and an eMoto. It has characteristics of both. Handling wise, it feels eMTB. Bike feel, cornering etc. Weight is a bit heavier than typical eMTB, but not by that much, as a big bloke, i dont really have trouble throwing the bike about. Its alot closer to eMTB than eMoto in that regard. Not really that much more than the e22.

But when that motor starts to spin up it really comes alive. The CYC X1 can spin up alot faster than you can pedal, and that is where it really starts to sing. Almost has a peaky 2t feel once it revs up. The motor sounds like a pissed off hornets nest, and it really starts to haul ass. Once you get up to that RPM, pedalling becomes redundant. You cannot pedal fast enough, and even if you could, the amount you could contribute VS the motor is insignificant.

Ive been playing around with the motor tune via the CYC app a bit. And i kind of want to emphasise that dual mode eMTB / eMoto characteristic. I want the pedal assist to work like a more conventional eMTB (except with more oomphf.) And i want the throttle to respond more like a moto. I have reduced the throttle torque to pretty close to the Bafang ultra level, but increased the peak power up to 4k. This means you can only access that hi power at higher RPMs. It kind of forces you to use the gears instead of rely on the huge torque dowm low. (Which is what tears up chains and cassettes.) And with the pedal assist, i have it kind of opposite, higher torque setting with a lower peak power assist. This gives it a strong pedal assist at lower cadence. Basically feels like a stronger version of the ultra.

Adjusting the motor tune like that does play into the dual mode feel. It rides like a eMTB when you need it to in the tighter terrain, but once you get some fast trail, you can really open it up and let it rip with the throttle.

 

[kaaskopf]

i like it, looks like great fun!

how much peak power?

 

[bram.biesiekierski]

i like it, looks like great fun!

how much peak power?

It certainly is great fun. A little bit of pure terror and plenty of adrenalin.

Ive been playing around with the motor control options in the app, trying to find a good match. Motor is currently set to 4000w peak, but with the torque slider reduced to about 2/3s. (About 2/3s of 280nm)

Because power = torque X RPM. Its not 4000w all at once, you dont get that power until the crank RPMs increase a bit. Hard to quantify but i feel this is a good way of ramping it in. That way you can kind of control how peaky the motor response is by what gear you chose. Intially it pulls down low like the bafang ultra, but as you ride the gear out, more and more of that power becomes available and it kind of switchs to "angry hornet" mode and it really comes alive.

 

[bram.biesiekierski]

I got the v2 104 to 130 bcd adapters today. I have installed them with a 42t bafang ultra chain ring. Initial impressiona are its an improvement.

 

[bram.biesiekierski]

I took the bike on a long ride yesterday. Rode until 60v (3v per cell), which is where the cut off is currently set. Got about 35kms of hard riding on the 4kw tune. Technically you could run the cells down a little further to say 2.8v / cell, but i dont really see the point.

Once the battery was gone, riding was very difficult. The motor has a lot of drag when its off. And the 42t chainring is optomised for going fast with the motor. Its terrible / almost impossible to ride without assistance.