Carbon single speed commuter

Richardab

Pedelecer
Apr 17, 2018
59
19
56
UK
OK i have finally got going with this build, following arrival of BMS batteries q100c 36v 201rpm plus 11.6 ah 48v battery with integrated 20a controller and lcd3 controls.

I have ordered rim and spokes to match the existing front one.

Wheel is laced with 2 cross using dt swiss alpine 3 spokes which are butted 2.3/1.8/2mm thicker at the hub j bend as i was nervous about the diameter of the spoke hole and thickness of flange. Wheel built up ok, i’m not a pro but have built a dozen or so wheels, these laced up at around 120newtons, the rim i used was a dt swiss asymettric with the spoke bed offset by 3mm so the dishing is a bit less than a regular rear cassette wheel. One thing i did notice in building the wheel was my usual technique of spinning wheel back and forth to locate wobble points was hampered by the wheel only really wanting to spin in the forward direction because of the clutch i assume.

Dropouts needed a little filing, but i wanted to keep this to minimum required. But have opted for a custom torque arm on both sides...overkill for a q100 but the tabbed washer wouldnt fit so the two torque arms are doing all the work. The arms are made from a piece of stainless angle massively ground down with just a flat plate arm running down the inside of the chainstay (instead of a washer) with a flat sided hole to lock the axle filed in one end and a small section of the steel angle remaining along the bottom that sits below the chainstay and resists the upward motion. Due to the inaccuracy of my hole filing the tab on the bottom is a few mm below the chainstay somi will pack out with thin nylon pad so it can directly bear on chainstay. I dont see why i need to bolt or clamp or clip the arm to anything, it will just push up against it....or have i misunderstood how torque arm works, i have to admit the kits available seem to take a simple rotational force and convert it into a pushing motion along the chainstay. Whith my version its just a simple rotational force....i think! I had to spring the carbon stays about 5mm to get all this in, it seemed very happy to spring that much without getting too forceful.

I really did not want to mess up the simple look of the bike, so i wanted cables hidden where possible, and battery hidden, my plan was to sit battery in the base of the saddlebag that i use for commuting to work and run cables out under saddle and down seat tube out of the bottom bracket to the pas and along the chainstay to the motor. The controller would be in the bag as would the lcd3, controversially my intention is to feed the up/down switch just outside the bag so i just have to reach back next to my thigh to operate it, but i am hoping that i will generally be able to find a happyish power level that deals with most terrain, if you recall my earlier enquiry threads i am a fit cyclist that commutes daily, i just want to double my mileage without wiping myself out, so very happy to input a fair amount when required. But we will see if this is acceptable in practice not being an experienced ebiker.

The crank is a carbon sram gxp style, i wanted the magnetic ring hidden and it looked neater on the back of the spider, i have cut out the centre and glued it on with hot glue gun, it seems to be stuck pretty well but if required i could do it with something more serious. I removed the pas sensor and after figuring directions glued it adjacent to the bottom bracket....which is eccentric to deal with the bike being single speed on a modern frame, there was a neat flat on the side of the bb so i stuck it there, it got knocked off the other day so i need another go maybe with something more stickiy, but my first attemp was a bit bodgy. Cable enters at bottom of bb where there is entry point for internal routing cables. Also ran the cable from the motor up around the bb too. They both emerge at the top of the seatpost, i drilled two holes in the top and threaded....with great difficulty, the wire up and out the top.

So how do i connect the battery in a removable bag. Although it will mostly remain on the bike as i will charge in place and my ‘work stuff’ will be in a light bag inside the saddlebag to remove when i get to work plus there is secure storage there so no need to remove saddlebag daily but when required i need a connector that could deal with the 9 wires from motor and 3 from pas. The best i could come up with was a 13 pin towbar socket! A bit big and crude but designed to be readily disconnected/connected so i wired it in with the socket end in the bag, the connection will be made in the bag and the bulky connector can slip uner the battery.

Inside the bag i didnt want the battery flopping about so i bolted the bottle-09 mount to the saddle bag frame with small stainless u bolts, whenthe battery is mounted it holds it neatly in the base of then bag. The connector, lcd3 and controller (it was a bit to long for the bag so is remote from the mounting frame) all sit below the battery leaving some space above for my stuff.

So almost there, mocked up a test and crank turning spins motor so i assume i have done everything right, stumped by not having rim tape for new wheel so i cant fit rear tyre plus a few other bits to do, but i think you get the idea from pics attached.

93990E48-951E-441F-A92A-D9EB4B7CB6FF.jpeg A6C1F48A-3256-46E3-AC87-6FCA7502EE0C.jpeg A0937BC4-94EF-4B09-9CEF-725C8911723C.jpeg 471ECEC9-919A-4988-B0E3-240F13B86367.jpeg A85CC042-2316-4EF6-A7E3-A53F03BBB0C7.jpeg D6E56417-1AE0-456F-BC02-403396CAB9B2.jpeg F4152810-A702-43EC-AE92-3BEE6A8F1FA3.jpeg
CC167F6F-715E-4A91-A862-9165C391457E.jpeg 90EC3C8A-53FE-4C0D-841A-443442EE4FFA.jpeg
 

Vagos

Pedelecer
Dec 18, 2017
37
5
42
Greece
Really cool looking and clean installation. great idea to hide the cables ( maybe i will try that to my steel single speed), but i noticed a small crack on the tube next to your crankset. Is it from something else or that happened when you drilled the frame? Or isn't a crack at all?
 

Richardab

Pedelecer
Apr 17, 2018
59
19
56
UK
Really cool looking and clean installation. great idea to hide the cables ( maybe i will try that to my steel single speed), but i noticed a small crack on the tube next to your crankset. Is it from something else or that happened when you drilled the frame? Or isn't a crack at all?
I noticed that on the photo too!, nothing to do with my modifications, but I will have a close look tonight. I didn't drill the frame at all, there are entry points at the base of the BB which I fed the cables up and around the BB up the seat tube. Only holes are in the top of the seat tube. I don't see them weakening anything.
 

Vagos

Pedelecer
Dec 18, 2017
37
5
42
Greece
I noticed that on the photo too!, nothing to do with my modifications, but I will have a close look tonight. I didn't drill the frame at all, there are entry points at the base of the BB which I fed the cables up and around the BB up the seat tube. Only holes are in the top of the seat tube. I don't see them weakening anything.
Yeah, those holes on the seat tube are to small to cause problems. You just gave me the "hide the cables" bug and i think i'll try it.
 

Richardab

Pedelecer
Apr 17, 2018
59
19
56
UK
First test ride today. Wow, ok, lots of punch from pas3 and above, even 2 had enough to wizz along at 20mph with me only helping a little. Hill climbing was very impressive, my nemisis hill just down the road from me, which kills me every day on the singlespeed grinding up it at 5-6mph by the top was 15mph in pas 2 with me helping a fair bit or 18-20mph in pas 5 without much help from me.

All seems to have held together ok, i am understandably going to keep my eye on the torque arms and drop outs, but it looks ok.

The weight is obviously drastically increased, the bike weighed 8.6kg originally and the empty saddlebag i was using before added over 1kg. Its at 16kg now and is all at the back so noticable when picked up, but not really while riding.

Questions:
Is there any lubing i need to do to the q100, now or at intervals? This bike gets used for regular commuting 5 days a week rain or shine and i will be doubling its mileage to 32miles a day.
Are there any specific settings i need to change in the lcd3, i found the p1 setting and changed to 202 as instructed somewhere on this forum, any others i can tweak that make things better.

I think i might need a bigger chainring on the singlespeed though, i was spinning out over 22-23mph and i could still feel the motor engaged at that point but was barely able to help it out.

Right now on to build two, i bought 2 motors a q100 and a q128 because i wasnt sure which to use and the motor was the cheap bit of the package so my plan is to build a hardtail 29er with the q128c and use the same battery. I don’t think it will be able to be quite as stealthy as this build, but i will try. I will put a build thread up when i get the plan formulated.

C35C9630-19CD-4028-95C7-962C77A9D738.jpeg 65CDD059-B0A7-4FC9-ABB3-FFF5ED41C2E1.jpeg D0B72D53-1ADA-45CE-8AB7-31C5F79C4881.jpeg 5760BED6-E2B7-4BDA-AE02-68D738C469F0.jpeg
 
  • Like
Reactions: Julie

Richardab

Pedelecer
Apr 17, 2018
59
19
56
UK
Been commuting on this bike a bit (I tend to ride offroad commute during the summer) so I can test it out and shake out the bugs before full time duties this autumn/winter.

My average speed has massively increased, It was around 15mph peddling, now I average 20mph, with cruising speed around 22-23mph. Battery life has been disappointing at first, I think this is due to the top speed in the low 20's and my gearing on the singlespeed being more suitable for 18mph so I felt like I was spinning out and barely able to help the motor at the top end which meant I was probably using alot of battery juice whilst spinning my legs frantically. I have just changed the front chainring for a bigger one and this morning it was so much better at 90-100rpm and 22mph. It did make hills considerably harder so I was more reliant on the motor. Overall it looks like it should make a saving on the battery as I was in PAS1 most of the time. I suspect that proper gears would actually help more, but I am reluctant at the moment to fit them, but it is a fall back if I need to make the most efficient use of the battery.

I am not happy with the weight balance all being at the back, it makes the bike unwieldy to carry when I get to the train station and although I cannot feel it when riding, if I stand up on the pedals its really noticeable and with the bigger gearing I feel the need to stand up on hills.

So I am developing a Mk2 version of the bike with the battery mounted forwards, It should be just as stealthy and hopefully better balanced.
 
  • Informative
  • Like
Reactions: Julie and Woosh

Richardab

Pedelecer
Apr 17, 2018
59
19
56
UK
Mark 2 version competed. I have the battery bolted, upside, to the underside of the handlebar, then a bikepacking drybag is sleeved over the lot, wires run up from the BB inside the downtube and out one of the derailleur cable ports and straight into the bag. For the moment I have mounted the LCD on the bars, its ugly and not very stealthy, but its useful for a bit to get a better understanding of wattage and voltage use, I am already getting a feel for what PAS 1,2 and 3 feel like so don't need the LCD so I will put it inside the bag soon. The thumb control is super neat just under the brake lever, much nicer than reaching round onto the old saddlebag.

The major change is the weight...it 'feels' several kilos lighter. The bag is around 1kg lighter than the previous saddlebag but I think its mostly down to balance, I can pick the bike up by the top tube in a normal manner and it just feels like a normal heavy bike rather than this unwieldy beast with all the weight at the back.

Handling wise, the steering is heavier, but I have run bar bags before and the feel is the same. It does mean I can get out of the saddle without the bike going all over the place now..

There is a zipped pouch on the front of the bag which is just big enough for my tools and pump and work stuff. Any more than that and I will clip the now redundant saddlebag back on, but I tend to travel light.

With the single speed gearing sorted and riding on PAS1, with occasional 2 and 3 for hills I am doing my 32mile round trip at 19-20mph average speed using 60% of the battery. Most importantly the overall door to door time is less than it was with the previous 16 mile round trip plus longer train journey and I feel about the same level of workout.

The Q128c emtb is now underway.

IMG_4396.JPG IMG_4399.JPG
 
Last edited: