Joined this forum because I found an excellent older thread about e-bike motors and things. But it’s a bit old and maybe everything’s changed (one of the motor companies mentioned that looked promising has just recently gone into liquidation…)
I’ve made about 12 frames and 6 forks, all TIG, so I’m fairly confident with the basic process. But this is my first ebike.
I’m thinking mid-motors sound like the best, and I can get a “Bosch Gen 4 motor casing” from Ceeway, which is our framebuilding supplier here in the UK:
And then I guess I need to buy a motor, controller, and battery from Bosch? Do they sell them one at a time to custom builders? What about the crankset? Is there a special Bosch one, or does it present an axle on which I can attach regular parts? (Insofar as there is any such thing as a “regular” part these days). What kind of BB shell width and chainline do I end up with?
I’m assuming it doesn’t really care what I have at the back. Would something like a 7-speed Nexus hub gear be suitable? I’m thinking probably MTB style hydraulic disk brakes.
As for the frame itself, e-bikes tend to be quite heavily built. Would “single oversize” work well? (1 1/8" TT, 1 1/4" DT)?
My main comment is ‘I dunno’. From there I will add that some IGHs (shimano Alfine is the one I have experience with) will not handle a motor drive. Rohloff may. Alfine also has limits on the gearing that it will withstand (front/rear ratio has to be bigger than 2:1 or something like that).
Thanks! That’s useful to know about the hub gears. Since posting that I have been in contact with various bike shops and specialists, and also Bosch and Shimano.
It turns out that it’s all quite “Big Brother”. Under both systems you need to do some kind of setup involving connecting a laptop to things. This is basically to tell it the wheel size but, under the Bosch system at least, requires having an OEM frame-number registered with Bosch.
I guess in part this is so you can’t easily hack it to provide assistance above the legal limit of 25kph, which is reasonable.
So I contacted Bosch and it seems their policy is to discourage small framebuilders. They want everyone just to shut up and buy a Trekgiantspecializedcannondale or whatever from China. Not a vision I share.
One of the bike shops I had spoken to had also tipped me off about this and suggested this was why Cotic (a medium-sized outfit making very nice MTB frames here in the UK and probably also in Taiwan) were using Shimano on their e-bikes: Bosch didn’t want to work with even somebody of their size.
I then contacted the UK’s Shimano distributor and spoke to someone who was extremely positive and helpful and gave me some other contacts. So I will update this thread when I know more, But it’s looking much more hopeful.
As for why Ceeway have a Bosch motor cabinet available, I think that’s because they happen to have a customer for it (who has managed to solve the Bosch supply issue somehow). It’s not a problem for me to fabricate a cabinet for a Shimano motor. It’s just because they had a Bosch one that I mistakenly concluded that everyone was using Bosch.
I was told by Bosch Australia if I buy a second hand bike and use the hardware out of that they’d offer service support at least. Otherwise they are only interested in MOQ that are not possible for small builders. The only options really are Shimano, TQ and Intradrive. Intradrive combines teh gearbox and motor into a unit and uses the Shimano mounting pattern so you have some flexibility in drives.
Cotic are using Shimano because they buy a lot of other stuff from the UK importer on a monthly basis so they get around the 100k ISH min quantities.
Look at bafang
In the UK, there is a programme that will allow you to buy Shimano drive units in quantities as low as 5. I doubt they would extend this to ‘hobby’ builders or brands that don’t have a demonstrated level of experience/quality/commitment.
Mounting, I’d suggest copying what Cy at Cotic did and make your own cabinet. He’s noted that it saved considerable weight over the cast ones available.
To future proof mounting you could make your frame so that it’s agnostic to motor mount and use a set of adapter plates that interface between the frame and motor.
I second that hub motors are the way to go. Grin (ebikes.ca) has good framebuilder friendly options in NA.
I own a Bosch bike (my wife has another one) and have built many hub driven bikes and I can get a better riding bike using a hub motor and torque sensing BB. Mid-drive bikes have massive Q factors and often have reduction gears between the cranks and chainring that kill the riding experience. My hub drive bikes ride like a regular bike if the battery is removed.
Yes I think it would be quite easy to make a cabinet-- they aren’t very complicated. I just (completely incorrectly) inferred from the fact that you could get one from Ceeway that that was what everyone was doing
There are also plenty of e-bike “conversion kits” that attach to a regular BB shell rather than having a cabinet so I could just use one of those. It’s not clear that the cabinet adds much although I suppose it might mean using the motor itself as a stressed member.
Where are you based and what kind of bike are you building? Reynolds has teamed up with MAHLE to bring X20 and X30 to steel and titanium framebuilders. Many builders are already using and you can get real light bikes. On my shop we managed a 14kg complete bike with motor and battery in Reynolds steel…
I am based in UK and buy most of my tubes direct from Reynolds. They are very friendly and a pleasure to work with.
Have found this page and will have a read:
The bicycles are both kind of general purpose city/partypace-adventuring type builds. One will have a kid on the back (~20kg) and the other a small dog on the front (not very heavy, but I’m thinking of a rack attached to the HT rather than to the fork).
I would stay away from Bosch or Shimano. The bike you make will become a paper weight when Bosch or Shimano decide to discontinue and you can no longer find parts/support. There are great mid drive kits (I’ve used Bafang) that you can install on any bike that will serve you well. I know the bike store people will steer you away from the kits but they have their own reasons and it’s not because the kits are inferior. By the time you figure out your cabinet for a Bosch or Shimano system, they will have come out with a newer unit that doesn’t work with your cabinet leaving you out in the cold.
There is a very large and growing community of people using ebike kits. If you stick to the popular brands, you will have a lots of support online and an endless supply chain of cheap parts. I am a hobby builder and economy is usually the top of my priority list when planning a build. Bosch and Shimano are very pricey and will not deal with individuals.
Thank you to everyone for all the excellent answers! It looks like my options are: the Mahle system from Reynolds, which looks very nice, or a kit like the TongSheng TSDZ2B (250W, set up as pedal assist only).
So now I’m wondering if the Mahle will give me enough torque for a city bike in this place:
Assuming total system weight of 100kg, 55Nm will hold that on a 2% grade according to my math, and give you about half as much extra torque as a 60kg rider standing on the pedal in a 1:1 gear.
But the TongSheng is 80Nm, and that’s at the crank, so I’d get 105 at the wheel driving through a 38/50 bottom gear. Nearly twice as much.
Have also posted this on a more generic cycling forum to see what people’s experiences with these systems and ones like them are.
OK thank you to everyone for all your help, and a final update to this.
Shimano are much keener to help than Bosch but you will still need minimum order quantities of somewhere around 20 or so.
The Reynolds/Mahle “ReyDrive” system has no MOQ and is very nice, especially if you want a discreet and low-weight system. Pricing is extremely reasonable, you will get an official warranty and all that good stuff, and they are great people to work with.
Otherwise your options are aftermarket “conversion kits” such as those from Bafang and TongSheng.
Bosch, Shimano and Mahle systems are all somewhat “locked down” to the extent that only very privileged people have access to the software needed to set them up (set the wheel size basically). This is probably more due to complicated regulations around selling anything that counts as “electrical equipment” or something than nefarious motives on their part.
But in the case of Reynolds the way it works is they can set up your system for you. Mahle have given them access to the software.
None of these regulations seem to apply to after-market kits, and you can easily buy ones to make e-motos that will be completely illegal to use without licenses and motorbike helmets etc. However they also mostly seem to sell legal kits as well (like the one I’m getting).
In the end I decided to go with the TongSheng rather than the Mahle because I want to make sure these bikes, which are for use in a very hilly city and carrying extra weight, will have enough torque. With a mid-drive I will have more torque through typical gearing and it will be possible to adjust the gearing if necessary.
It’s quite possible the Mahle would have been fine. But I don’t know that. It’s certainly something I will keep in mind for future builds.
The TongSheng is designed to fit onto a regular frame with a BSA BB. It says it supports 68 or 73mm shells, so I will wait and see what it looks like when it arrives, and then probably use 73mm shells since I suspect they will just give you some spacers for if you have a 68.
I’m going to make my frames “single oversize”, with touring-grade seatstays.
