10 kW Giant Glory 1

[flat tire]

Nice build. Everything looks well thought out. Additional benefit might be a triple crown downhill fork for a little more weight in the front.

What are you doing about brakes? I have Magura MT7 on a similar bike that weighs around 85 lbs. Stopping hard from 40 or 50+ MPH is not possible because the brakes will overheat.

 

[galp]

I bought the bike with boxer fork but had to replace it with current one to make room for batteries/enclosure. I now have a sick mountain bike with boxer front fork and no rear suspension. I bet you haven't seen that before. :lol: :lol:

I have the same Magura. I have 75 kg and bike another 40 kg. I don't have problems stopping from 60 km/h. Huge and heavy Hayes rotors help a bit I think. I'm also using ebrake.

Speaking of e-brake I was thinking to mount a magnet on rear brake handle and hall sensor somewhere on the handlebar. That way I could use ebrake with my existing brake handle before mechanical brakes start to grip. It would be a lot more convenient than using separate thumb throttle.

 

[HolgiB]

@galp: Haven't been following your build for some time but the battery box is a nice upgrade ! :thumb:

As for a brake sensor in regard to use recuperation you can use pretty much and combination of reed contact and permadyn magnet.

Also there ready solutions available like this:
https://de.aliexpress.com/item/Ebike-Hydraulic-or-Mechanical-Brake-Sensor-BAFANG-mid-crank-drive-motor-BBS01-BBS02-BBSHD-Cut-Off/32837756174.html

You would have to cut the cable end though and solder on a connector matching your controller.
But I guess this is not a big issue for you

Oh yes, there is one thing I forgot to add: A magnet switch used for recuperation / e-braking has a big advantage compared to using a thumb throttle as regen input. You have only on defined level of brake force which you can not change. A rather "digital" brake so to say.

 

[galp]

Yes I could use a simple switch but I like variable electric brake. I just have to integrate it so It'll work seamlessly with existing mechanical brake.

I gave the battery/electronics enclosure a paint job and some protective rubber edges. Looks like this now:

Air brush art would be nice. I have to find an artist first.

 

[HolgiB]

The enclosure looks much cleaner now. May be some nice decals would work as well ?

As for the brake sensor: There is also another (digital) solution called Tripwire:
https://www.ebikes.ca/product-info/tripwire.html

It might be a bit hard to come by in Europe unless you import from ebikes.ca yourself.

A analogue brake sensor would be cool so you have increase e-braking if you pull the brake lever more but I can hardly imagine how to build something like this unless you attach a linear potentiometer to the brake lever somehow.

 

[galp]

Linear hall sensor would work. Same type that is used in cheap twist and thumb throttles.

 

[larsb]

seriously, that snow riding!
How old are you
any sane person would've quit after the second crash.

 

[galp]

For the last few charges the battery started acting strange. It wouldn't charge to 84 V and would hold only 700 Wh instead of 850-900 Wh. At first I thought it was just cells getting old already but then I figured one cell probably went bad or lost connection.

Here's what happened: my battery is in 20S5P configuration. One cell lost contact so somewhere in the battery only 4 cells were working in parallel instead of 5. This segment in the battery was discharging and charging faster than others. When charging, the bad segment would rise above specified overvoltage threshold (4.3 V) and BMS would cut the charge. Other series segments weren't full so total battery voltage never reached 84V. When discharging the bad segment would discharge faster and reach undervoltage threshold (2.8 V) and BMS would once again cut power although other series segments still had some charge. This would happen at 65 V.

To confirm my theory I discharged my battery and measured cell voltages. I calculated mean cell voltage and then calculated difference to mean voltage to individual cell. Can you spot the bad series segment?

I then charged the pack and once again measured cell voltages. The bad segment now has higher voltage than other segments. Number 17 is probably measurement error since voltmeter resolution jumped from 10 mV to 100 mV.

All was done in excel. I attached the file if anyone wishes to use it. You can either measure absolute voltages from ground reference (ie. 3.3V, 6.5V, 9.9V, ...) and then calculate cell voltages or directly measure cell voltages (ie. 3.3V, 3.2V, 3.3V, ...). Make sure to measure twice, once fully discharged and once charged to about 80% of full capacity (before balancing starts). Bad segments will have lower voltage than others when discharged and higher voltage than others when charged.


Anyway, I took the pack apart and quickly found that one cell lost contact. Before I soldered it back I measured its voltage. It was discharged so I charged it first before soldering it back to the pack (pack was charged).

 

[galp]

I'm getting my bike ready for summer heat. I installed 60mm server fan to cool down the motor controller. I also developed custom electronics to read temperatures of motor controller and batteries to regulate fans accordingly. I still have to figure out how to cool the batteries since they reach about 55°C @20°C ambient.

 

[galp]

Pushing 8kW+ from battery going slightly uphill on a gravel road.

[youtube]PQX_hYMwkyo[/youtube]

I'll have to align rear brake rotor.

 

[galp]

A lot has happened since last time I posted.

I broke my rear rim and a spoke... It was mainly because I landed too short on a double and poor spoke/rim maintenance. Maybe also because the rim was chinesuim. Anyway the broken rim was replaced with Mavic EX729 and some heavy duty spokes by a professional. It cost 65€ for a rim and 90€ for spokes and lacing. I also had to replace front and rear brake pads. Looks like I'll have to replace them every 500-1000 km.

Bike is running again, but with weather warming up everyday I'll have to find a better solution for cooling the batteries and electronics. Compared to winter I'm at 20°C less thermal budget and it already shows. It'll double when summer heat hits. I don't know, maybe I'll just ride at night to avoid 40°C summer heat.

Here's some trail shredding at my local bike park. It's quite small and I'm used to all the jumps and trails with my regular bike. Things are a bit different if you're riding a 40 kg electric cow.

[youtube]B9t0q2X3rYU[/youtube]

 

[peters]

I speak for motorbike rim, spokes and tire at least on the rear wheel. I changed to them 3 years ago and since then I did not have any problem, did not even have to replace the tire, although I ride only 1500-2000km in a year. But before that any bicycle tire wore out under 1000km and also had to be careful on rocky trails because 2 times my almost new tires ripped, once on the tread, once on the sidewall. Bicycle tires are not made for torque and power. Spokes also broke and rim damaged.
Motorbike wheels don't have any of these issues, and furthermore the bike is more stable because the lateral stiffness of the wheel is much better. I changed only the rear wheel to 18" motorbike parts, but I think that changing the front one would also be a big improvement in stability.

 

[galp]

Yeah, I decided to go with motocross parts. I'll install 19" rim and tire on rear wheel. It's only about 5 cm smaller so I can keep the front 26" bike wheel. Front wheel seems to be holding fine.

Rim: https://www.smpro.co.uk/smpro-platinum-rim-19-x-1-85-36-matte-black-mx-drilling-honda.html
Spokes: https://www.e-spokes.eu/
Tire: https://www.bartog.si/en-us/showProduct.aspx?SEName=moto-gume-70100-19-42m-starcross-ms3-f-tt-michelin&ProductID=244850

Does anyone know if 70 mm wide motocross tire is actually 70 mm wide or is it a bit wider inflated like bike tires?


I'll also upgrade my battery system. I'll install 120 extra 18650 cells in 20S6P configuration. With 220 cells the battery system will yield 1980 Wh total capacity and 220 A peak current. So far the battery has proven to be the bottleneck. Expanding its current capacity by 220% will probably move the bottleneck role to motor as it will probably overheat easily.

I'll also upgrade the motor controller with BESC G2 which should be capable of 400A phase current.

 

[peters]

I guess the tire width depends on the manufacturer and the width of the rim. My Vee Rubber 2.75" (~70mm) is actually 73mm wide.

 

[mattthemuppet]

holy cow bells, what a build! Loved the videos too, especially the snow one. Riding on snow with standard mtb tires isn't trivial, doing so with several horsepower is even less so!

How do you find the bike on jumps - is it still balanced? Does the power help you get the take off speed right? I imagine it's quite the upper body work out with the extra weight!

 

[Helionn]

I'll also upgrade the motor controller with BESC G2 which should be capable of 400A phase current.

Hi Galp! I am following your work with great interest, I am developing a driver for a drone and your work is serving me a lot because I am still a newbie. did you change the controller for BESC G2? How does it work? Thanks for everything!

 

[galp]

I still haven't tested the new motor controller. I'm planning to do it soon.

 

[Merlin]

you would have so much more fun with a mid motor and not that fat cow in the rear wheel

 

[galp]

I decided to get rid of bike rim and tire. One of the main issues is that even the strongest bike rim is not strong enough and that bike tires are not build for this kind of torque. I had to replace tires every 300 km or so which was getting expensive. I did some research and found a way to get all the parts and assemble a proper rear hub wheel.

I first looked for a rim. I was deciding between 19" and 18" and went with the later. I did some calculations and found that fully infalted 18" motorcycle tyre is only 6cm smaller in diameter than 26" bike tire. A bit smaller wheel will also give a bit more torque (10% or so). I went with SM pro MX rim. They have "old stock" rims on ebay that you can get for around 100€.

Another problem was to find a tire to fit in my bike frame. I didn't want a MX tire because it sucks on tarmac. In the end I found Mitas H03 18-2.75 which fits in the frame perfectly with 1 cm of clearance on each side and is perfect for tarmac and gravel roads where I ride the most.

I then measured my hub and rim and put all data in few hub motor spoke length calculators online to get the length of spokes I needed. Rim had 8.5 mm holes for nipples and motor only 3.8 mm holes for spokes. I did a compromise and went with 3.4 mm spokes (9G) which have 6.5 mm nipples. They fit perfectly but I had to drill motor spoke holes from 3.8mm to 4.2mm.

I started assembling the wheel in one cross pattern. It was easier than I expected but took about an hour. I then mounted the wheel on my bike to true it. This took another hour to get it right. You need a few youtube tutorials and a lot of patience.

And here it is sturdier as ever. The only real downside is that the rear wheel is now even heavier for about 2 kg.

Shopping list (EU):
Spokes: https://www.e-spokes.eu/p13,stainless-spokes-sm-3-4mm-40pcs.html
Rim: https://www.ebay.co.uk/sch/i.html?_from=R40&_trksid=m570.l1313&_nkw=sm+pro+rim+18%22&_sacat=0
Tire: Mitas H03 2.75-18 just for price reference: https://www.bartog.si/moto-gume-275-18-48p-h-03-tt-mitas-p-171821.aspx
Rim strip thing to protect tube from nipples and sharp hole edges
18x2.75 tube

 

[galp]

I took a few thermal photos of my bike today after a ride in cold weather.

Motor, motor wire and air shock absorber generate the most heat as expected. Sadly you can't see electronics because it is enclosed.

Bike throttles itself after about 10 minutes of riding. I still have to install active air cooling on new motor driver (BESC G2) that will solve this issue.

 

[szramol23]

Hi . cam you send me how you make rear wheel supports .
some photos or measurements please .
my motor and all parts on order
Thanks

 

[galp]

Here are step files and 3D pdf. You need adobe acrobat reader to open it properly. Hope this helps.

 

[galp]

So today I was trying to run 370A through my poor motor and this happened. BESC-G2 is now tested up to 370A without issues. Well, except for the axle.

 

[Tommm]

So today I was trying to run 370A through my poor motor and this happened. BESC-G2 is now tested up to 370A without issues. Well, except for the axle.

What happened as you were riding? Did you crash?

 

[galp]

No, this happened when starting up from standstill.