After owning a Dengfu e22 for a few years, I have decided to build a new bike. I love the e22, but have become accustomed to the power and crave more. When I bought the e22, I wasnt really that concerned with geometry, and just wanted an affordable powerful bike. But after riding it, and listening to the likes of Brian Cahil, I began to realise the bike is actually a really good match for my riding style and feel, and the type of terrain i tend to ride. The e22 is an awesome platform, the long rear end, upright riding posistion and reliable horst link handle the power and ride great at speed, and really compliment the motor combo and make for a great fast trail bike. The frame has been bullet proof reliable, and I am very impressed with the quality of the brand.
Ofcourse the Dengfu e55 was a strong candidate as a replacement. It also has really long chainstays, and on paper looks to have similar charactaristics. With some slight improvements in the way of a larger battery compartment, more upright seatpost and slacker head tube. Which I think are all good improvements, and shouldnt detract from the e22s feel. But, it doesnt really offer much of a performance increase other than 52v instead of 48v.
The Bafang Ultra has been a solid and reliable workhorse, and I have no issues there. But its not exactly optimised for eMTB. More power was a key consideration, and I have had my eye on the CYC X1 progression. Then with the likes of Bonnell bringing the 775mx to market, it cemented it for me that I wanted something along those lines. So that is where the idea to convert a e55 to accept an X1 was born.
I was also very seriously considering a Commencal DH Supreme v5. Because everything I have seen and heard of that bike sounds amazing, and the front triangle has enormous real estate for batteries. Yes, I know the Supreme is not even in the same category as a Dengfu e55, but I feel it would have been a very good candidate for the type of bike I am envisioning. The longer travel would also be greatly appreciated, as I feel the e22/e55 could do with a little more in that departemnt. I dont particularily ride crazy terrain that demands it, but i feel that at decent speed, even small hits make for big compressions and can blow through the limited travel available on the Dengfu frames.
In the end I settled with the Dengfu e55. I like that the brand is not that well known, and I like the process of building a bike up from scratch as opposed to converting what is effectively an already complete bike. I also feel the integrated in-downtube battery is a cleaner look than a strap-on battery pack, even though capacity will be limited at approx 1kwh. I think having smaller shorter duration batteries that can be hot swapped would be better than a bigger longer lasting pack that is more difficult to swap. The choice was also partly to do with the maximum chain ring size. And lastly, by converting a mid drive back to a BSA bottom bracket, and then over to a X1 means i have control over adjusting things like BB drop, F/R balance, because the adapter is a custom component, and i could adjust geo quite easily by altering BB placement.
I purchased a red e55 frame from Dengfu directly, which arrived promptly and looking good. I do like a bit of bling on my bikes and quickly decided a black and gold theme would look great against the red frame. Its also where the bike got its nick name of the Golden Goose. So began a bit of a shopping spree collecting the parts needed. I wanted good quality gear, but also tried to take advantage of any deals / sales that was on offer.
With suspension, I opted for a Cane Creek Kitsuma Coil as one came up for discount. I have one of these on another bike and have always been very happy with the feel, once you figure out the complex setup ofcourse. A yellow 575lb Ohlins spring compliments the colourway I have in mind.
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As others have found out, the way Dengfu has implemented the shock mount is a bit of an afterthought on the e55. It appears they have cheaped out and used the same bolt as the e22 instead of manufacturing one specifically for the e55. But due to the frame mounting shape, they had to drill quite deeply into the carbon to make it all work. It looks like shi1t, and has very little material to bear the load. I actually bent the shock bolt on my e22, so when I saw the e55 arrangement, I knew right away that was never gonna fly.
I pondered the arrangement and designed a solution that involves using a grade 12.9 precision ground 8mm shoulder bolt, and then turn down 2 tapered aluminium adapters to interface directly with the carbon frame. My lathe skills are quite amaturish, and i wanted something a little better than I could make myself. I had always wanted to learn 3d modelling and this was a good oportunity. So I got On-shape and spent a few nights teaching myself how to use the software, and designed the parts. I sent the files to JLCCNC and had them manufactured from 7075 aluminium and then hardcoat anodized black. They turned out great. Perfect fitment, and installed depth. The shoulder bolt a snug fit and perfect length. I am confident it should handle the heavy spring loads fine.
They are designed to be a slight press fit into the frame. So that way they remain inplace when the bolt is removed for shock removal. I went with a snug fit, as i wanted it all to be very tight fitting into the frame, to prevent movement and reduce wear n tear, and wallowing out of the carbon frame during use. The outside diamter is just a whisker under 15mm at the outside edge of the frame, and it then tapers down to approx 14.8mm, at the inner edge where it then transitions to the 45° bottom taper. This worked out pretty good.
One of the adapters is basically just a fancy washer that sits under the head of the shoulder bolt. It is counterbored so the head sits flush, and profiled to fit into the bore in the carbon frame.
The other adapter is basically a fancy nut, that the shoulder bolt can screw into. It has a 8mm internal bore on the inside face, so the shoulder bolt can insert into it before the threads fully engage. The idea was to allow the shoulder bolt to transfer the loads into the adapter, and not rely entirely on the threads. The outside face of the nut has 2 small holes that i can use a pin wrench / circlip pliers to hold when tightening. Although the press fit into the frame is tight enough that this wasnt needed during instalation.
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Front fork I splurged for an Ohlins DH38 m1. I actually got a commencal V5 take-off directly from Commencal at a discounted rate, probably due to the release of the m2. It was still pricey but significantly cheaper than the ticket price elsewhere. A coil conversion was first up, because thats just the sort of guy I am. I ordered a few different grade coils to choose from. I just much prefer the feel of a coil, and Im stubborn and set in my ways. So i didnt even bother with air. Choosing a dual crown wasnt ideal, as the e55 is very wide on the top tube near the head set. That greatly impacts available steering angle. But too late now. Maybe if it gets to bad, ill swap to a single crown, and fit the DH038 onto the e22. I might swap to the biggest offset tripple clamps, that will get a bit more angle by moving the tubes forwards. Ideally id use the shortest offset clamps, as that makes the most stable steering.
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With the longer than intended fork, and the fact the e55 is already slacker than the e22, I was concerned the front would be ridiculously slack for my liking. Which it would have been. Plus the integrated headset cable routing on the e55 was a major turn-off. So I opted for a 1.5° steeper Works headset kit. And that is where I ran into the second headache. Dengfu headsets measure 56mm top and bottom, which on paper sounds like a common ZS56 arrangement. But the Dengfu cups and frame counter bore is quite shallow. Significantly shorter than the Works components angle headset i had orderd. Thankfully this was actually easily over come by turning down the new headset cups with a large 45° chamfer on the lathe, so they match the shallow counter bore in the frame.
With a bit of careful measurements and some back and forth with Works support, I came to the conclusion the Works cups have enough meat in them to machine, just. Its just a little bit finicky to chuck them up as they are so small, and the dont have concentric faces, IDs or ODs due to the nature of how angle sets work. I pressed the modified cups into the frame and the installed height seemed about right. I think it will hold up over time.
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In order to get away from the headset cable routing, I had to punch some holes into the frame. But where to do it. After much deliberation, i decided to put some small holes into the inside of the triangluar cut-away in the e55 frame. This allows for a relatively staight cable run, aswell as keeps the penetrations out of sight. I got my sharpest step drill and got to work. Then cemented in some rubber grommets. It aint my best work, hopefully hasnt weakened the frame too much.
For the drivetrain I opted for a CYC HD 5spd. I know the X1 Pro doesnt really need gearing. But the ghost pedalling feel sounds absolutely horrible, so I needed something. I blew up a couple of Kindernay IGHs on my e22 before recently swapping to the CYC 5spd, so I figured it would make sense to run both bikes like that. Time will tell how it holds up. Drivetrains is my achilles heel with these bikes. Nothing has been able to reliably handle my abuse yet.
For the wheels I decided to build them up my self. The CYC 5spd kit comes with a rear hub, so I laced that up to the new DT Swiss FR571 using Sapim Strongs and brass Squorx nips. I went 29", as the bike is gonna be fast trail use primarily. Up front another DT FR571, laced to a Spank Hex, again using Sapim Strongs. (Heavy for a front wheel, but strong as anyrhing). Tyres I went tanwall Schwalbe Magic Mary / Big Betty in super gravity orange stripe option. And lastly, swapped over to the gold rim decals.
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Brakes I choose to use Formula Cura 4s specifically because of how good they look in gold, and how that would match my colourway. A purely superficial aesthetic choice. I have always used Hope brakes, and i have never had any need to change. But these Formula Curas are sex. I went out on a bit of a limb, as they were unknown to me, and id seen mixed reviews. I did end up frankestein-ing in some Hope hoses, as i didnt like the look of the standard hoses, and i needed the 90° banjos aswell. I also went straight to some Galfer pads. I also choose Hope 220mm rotors too.
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Pedals are bronze Spank Oozy. All my bikes have Spank Oozy. I ONLY ever ride Spank Oozy. I did actually buy some Raceface kashmoney Atlas pedals. But my OCD kicked in and I changed my mind and went back to the tried and true Spank Oozy. I think im up to like 5 pairs now.
The rest of the componets i pick and choose primarily based on how they look / personal prefference / brand loyalty. Renthal Fatbars. Ritchy seat. Burgtec for stem, seat clamp, and UDH because of the really nice gold colourway. E13 cranks. PNW dropper. I bought about 3 or 4 sets of grips before i found the right combo of colour, width and feel. I eventually sertled on Raceface Gripplers in Gum colour. I threw in a few gold highlights aswell like valve stems, rotor bolts etc. Dropper remote is a Aliexpress unit. Things like gold cable sheaths etc also sourced on Aliexpress.
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The battery was the next big hurdle. The X1 Pros really sing with 72v. But jamming 72v into the Dengfu e55 battery case isnt exactly an easy feet. For me, maintaining the quick swap functionality of a removable in-downtube battery was a must. That way I can have a couple of batteries and swap when needed. The standard e55 battery case is a Reention Rhino case. These are typically made to 52v, 14s4p, but can hold a maximum of 60 x 21700 cells, but that doesnt leave any space for a BMS. In order to hit 20s / 72v and have enough instantaneous power and capaicty to be somewhat usefull, I need to use all 60 cells, arranged 20s3p, and use some high capacity / high instantaneous output cells like molicel p45 or Samsung 50s. And Id still need a decent BMS jammed in there aswell, around 80a capable to achieve a theoretical 5kw peak.
In order to achieve this 20s3p and still fit a BMS inside the Rhino case, I had to get really creative with the cell placement. The standard cell scaffold in the case is not optimised, the cell holes are quite large, and the cell pitch isnt that tight either. Plus there is alot of wasted space along the edges. I spent alot of nights re-designing a cell scaffold to fit the case, that would allow all 60 cells and an 80a slimline Jiabaida (JBD) BMS. I managed to do this by bunching the cells up, utilising all the vertical height at one end of the pack and stagering it, then at the other end of the pack, flattening the layout out, and using the full length available to squeeze a BMS ontop. I was splitting millimeters, and literally using every one available to me. It took me alot of time, many revisions and a crash course in On-Shape to get the design hammered out.
The cell scaffold is currently getting CNC cut from POM plastic by JLCCNC. I dont really know whats better between 3d printing and CNC machining, but in my mind, CNC seemed like the better option. They could achieve minimum wall thickness of 0.8mm, and i opted for a cell hole diameter of 21.2mm, resulting in a primary pitch of 22mm. Just enough to fit it all in.
The Rhino case is at minimum 73.7mm wide, which really doesnt leave much room for a 70mm+ cell and the cell interconnects and insulation. So I am sourcing some custom copper bussbars to be made. I couldnt use off the shelf bussbars as my cell pitch changes as ive massaged the placement in order to cram everything in.
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As for the motor mounting arrangement. I have began fabricating this myself. Basically 2 piece of 5mm steel, cut and drilled to match the m620 mounting bolt pattern, and then an off the shelf BSA bottom bracket shell. As much material removed from the plates to reduce excess weight. And then welded together with some spacer tubes between the bolt holes.
But the more i play around with 3d modelling, im pretty confident i could design something alot more professional, and have it sent off for CNC machining like the reat of the custom components. I will probably end up doing this.
Weight isnt really a concern for me. I just something i can beat up on over and over and not fail. So the heavy / meaty components are a must, at the expense of a little extra baggage.
Keep posted for more buid progress as it develops. The build is a slow burn, as with a 50hr work week, and 2 kids, I do not have much excess time for this project.
