eBrompton Build
- Thread starter StuartsProjects
- Start date
If You had gone back to basics and thought about what you needed for your project at the start, i.e. a battery that you could charge to less than 42v, instead of buying a battery, then figuring out how you were going to charge it, you could have bought a battery welder, a charger, a smart BMS that gives you control of all aspects of the battery and at least two sets of 10 cells for less than the £250 you paid for one battery; however, when you can buy/make a replacement cell-pack for £60, you don't need to worry about extending its life too much unless your only concern is about the environment, so you could go back to using a cheaper BMS, or three of these and chuck them when they wear out:
41.16￡ 40% OFF|2020 New 36v Battery 10s1p 5ah 42v 5000mah 21700 Lithium Ion Battery Pack Ebike Electric Car Bicycle Scooter 20a Bms 500w +2a - Battery Packs - AliExpress
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Can you suggest where you might get a 10S1P of Samsung 21700 50S 5Ahr at a lower cost ?
batteries need to be as safe as possible, so lowest cost is probably not an option.
Still, I did not expect Stuart to pay that much for a 36V 5AH battery though.
Indeed so.
Safety was the main reason for the XH-M602 setup; at fairly low cost, it adds protection against the charger overcharging the battery.
I also chuck the batteries in a fireproof bag, £27, for charging, I am not keen on my workshop burning down.
I realise that a lot of people find this safety stuff weird.
I paid £125 for my Malectrics arduino welder though that was some 4 years or so ago, One suspects they are bordeirng £200 now but haven't looked.
Before that I bought the Boss mini arduino one from Korea fo $80 but it went tits up , I got a replacement board from the seller but it still wouldn't work so I bought the Malectrics which has been brilliant , one needs a battery power supply as well.
Before that I bought the Boss mini arduino one from Korea fo $80 but it went tits up , I got a replacement board from the seller but it still wouldn't work so I bought the Malectrics which has been brilliant , one needs a battery power supply as well.
Conversion to trolley mode
Bare bones eBrompton works just fine, but in its basic state whilst its light enough for lifting in and out of cars etc. For taking it into larger shops, rather than leaving it outside to make the thieves happy then you need to fold and push the Brompton in shopping trolley mode, you wont want to carry even eBrompton very far.
Shopping trolley mode requires that you have wheels on the bottom of the folded Brompton so you can push or pull it around, just like a shopping trolley. A standard Brompton will have small wheels around 6cm diameter fitted to the frame by the rear suspension block, just behind the seat post. Whilst the standard wheels are OK for pushing the Brompton around on the floor to store it in corners etc, the wheel base is fairly narrow at 14cm so the folded Brompton is not that stable. To make wheeling it around easier its common to fit an extendible wheel set that changes the wheel base up to 24cm or so. The wheel on the right side pulls out on an extension, if it were out all the time you would catch your foot on it.
The rest of the wheeling platform is provided by fitting a rear rack and then another set of wheels go in the mount points s at the end of the rack. The general arrangement of the rear rack is shown bellow.
There are two basic trolley modes, the first trolley mode is what I use and I leave the saddle up a bit and stand behind it and push and steer the Brompton with one hand on the saddle, see picture bellow.
In the saddle up mode be careful if you decide to lift the Brompton up by its handle (the saddle nose) as with the saddle up the Brompton is not locked in folded position. To prevent it unfolding when you do lift it with the saddle up fit a strap around the frame tube and rear wheel to keep it all together, see the red velcro strap in the picture above.
The second trolley mode is to leave the handlebars up and use the handgrips to push the Brompton it in front of you, or drag it behind. This mode can also be used if the Brompton does not have a rear rack with wheels but does have a rear mudguard fitted with a single wheel on it.
With the trolley mode added eBrompton is at a stage whereby its fully useable for local trips, going into shops and train stations etc. I have not fitted the carbon mudguards yet, waiting for some titanium button bolts to arrive.
Bare bones eBrompton works just fine, but in its basic state whilst its light enough for lifting in and out of cars etc. For taking it into larger shops, rather than leaving it outside to make the thieves happy then you need to fold and push the Brompton in shopping trolley mode, you wont want to carry even eBrompton very far.
Shopping trolley mode requires that you have wheels on the bottom of the folded Brompton so you can push or pull it around, just like a shopping trolley. A standard Brompton will have small wheels around 6cm diameter fitted to the frame by the rear suspension block, just behind the seat post. Whilst the standard wheels are OK for pushing the Brompton around on the floor to store it in corners etc, the wheel base is fairly narrow at 14cm so the folded Brompton is not that stable. To make wheeling it around easier its common to fit an extendible wheel set that changes the wheel base up to 24cm or so. The wheel on the right side pulls out on an extension, if it were out all the time you would catch your foot on it.
The rest of the wheeling platform is provided by fitting a rear rack and then another set of wheels go in the mount points s at the end of the rack. The general arrangement of the rear rack is shown bellow.
There are two basic trolley modes, the first trolley mode is what I use and I leave the saddle up a bit and stand behind it and push and steer the Brompton with one hand on the saddle, see picture bellow.
In the saddle up mode be careful if you decide to lift the Brompton up by its handle (the saddle nose) as with the saddle up the Brompton is not locked in folded position. To prevent it unfolding when you do lift it with the saddle up fit a strap around the frame tube and rear wheel to keep it all together, see the red velcro strap in the picture above.
The second trolley mode is to leave the handlebars up and use the handgrips to push the Brompton it in front of you, or drag it behind. This mode can also be used if the Brompton does not have a rear rack with wheels but does have a rear mudguard fitted with a single wheel on it.
With the trolley mode added eBrompton is at a stage whereby its fully useable for local trips, going into shops and train stations etc. I have not fitted the carbon mudguards yet, waiting for some titanium button bolts to arrive.
Improvements to trolley mode
With the two sets of straight sets of wheels fitted the eBrompton is easy to push, but not so easy to steer and keep in a straight line. A suggested solution is Omni wheels.
The Omni wheels have rollers arranged so that one is always in contact with the ground, this means the wheels can move in all directions.
There are plastic Omni wheels that are cheap and light but they have plastic hinges for the rollers and they break quite easily when used on a Brompton in trolley mode. There are aluminium Omni wheels but they are not light. I was searching around and found a modified set of plastic Omnis wheels with metal hinges for the rollers that are advertised for the Brompton, no surprise really lots of stuff is made or modified for the Brompton.
These modified Omni wheels are a revelation, the folded eBrompton is very easy to push and steer, you can even spin it around on the supermarket floor. They have a significant advantage over the normal straight wheels and are a fair bit heavier, 78.7g versus 27.1g (for each wheel and bolt) but very much worth it.
With the two sets of straight sets of wheels fitted the eBrompton is easy to push, but not so easy to steer and keep in a straight line. A suggested solution is Omni wheels.
The Omni wheels have rollers arranged so that one is always in contact with the ground, this means the wheels can move in all directions.
There are plastic Omni wheels that are cheap and light but they have plastic hinges for the rollers and they break quite easily when used on a Brompton in trolley mode. There are aluminium Omni wheels but they are not light. I was searching around and found a modified set of plastic Omnis wheels with metal hinges for the rollers that are advertised for the Brompton, no surprise really lots of stuff is made or modified for the Brompton.
These modified Omni wheels are a revelation, the folded eBrompton is very easy to push and steer, you can even spin it around on the supermarket floor. They have a significant advantage over the normal straight wheels and are a fair bit heavier, 78.7g versus 27.1g (for each wheel and bolt) but very much worth it.
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Tanus airless rear tyre
I swapped out the rear Tanus airless tyre for a Continental Contact Urban air tyre with a Tubolito tube. Weight is around the same. The ride on the Continental Contact Urban is better, not so harsh.
Its a shame really, on normal cycle paths and good roads the Tanus is OK. The ride is not as good as an air tyre, but acceptable. With the Tanus there are no more punctures, no removing wheels when out and about nor the need to carry spares.
Many years ago when roads were kept in reasonable condition then Tanus airless tyres would have been OK in my locality. But in these modern times and with an overall national policy to apparently discourage cycling, road maintenance in my area seems to have been consigned to history.
Better tyres for front motor wheel
I previously had a problem with Continental Contact Urban tyres on the front motor rim. The rim appeared to be slightly different to a standard Brompton wheel rim and the Continental Contact Urban tyres would not hook into the rim properly. So I had fitted a Schwalbe Marathon plus on the front with a Continental Contact Urban on the back.
The Continental Contact Urban seems to have become the go for tyre on a Brompton, its light, apparently hard wearing and highly puncture resistant, see this video;
“I tour a lot, not had a flat in two years on the Brompton, in the thousands of miles, commuted to work, gravel paths, off road”
I wanted to have a handy spare tyre and when I found that the Continental Contact Urban folding tyres (from Brilliant Bikes) were cheaper (£28) and lighter (-44g) than the wired version I bought one. The wired version is £30 and a Schwalbe Marathon would be £37.50.
I decided to test fit the folding version of the Continental Contact Urban to the front motor wheel of eBrompton to see if I had the same problem as the wired version where the tyre bead comes off the rim on inflation.
The folding tyre was easy peasy to fit by hand, no tyre levers needed. Easy to get off too without levers so minimal risk of pinching the tube.
I inflated it to 90psi and it fits very well, nice and clean and even. Looks secure. I marked the edge of the tyre where it met the rim with a black marker all the way round on both sides of the tyre and removed it from the rim. I could see from the markings that the bead was evenly under the rim hook all the way around the tyre, good job.
Its rides well, at least in the dry, a bit smoother than the Marathon plus.
The front tyre I had previously fitted to eBrompton was a Marathon plus weighing 480g. The Continental Contact Urban folding is a mere 213g, so if these tyres are really as puncture resistant as the Schwalbe Marathons, then there is an overall weight saving on a Brompton for two tyres of 534g, cheaper too. Lets see how they last.
Adding the mudguards
The titanium button bolts arrived so it was time to add the mudguards. Ever since I started using a cycle for commuting, local shopping and touring rides, I have used full mudguards. Back in the day, circa 1977 I was the weirdo riding around on a custom Reynolds 531 double butted road racing cycle, fitted with full mudguards. I never have understood why so many cyclists go around on bikes that make them dirty when it rains.
The eBrompton mudguards are carbon, they don’t save much weight versus standard Brompton guards but they do look cool. The front mudguard stay is a titanium version. The rear mudguard is held in place by the rear rack.
The added weight of the mudguards, including stays, flaps and bolts was 177g.
Next steps
I was hoping that by now I would have a 10S1P battery of 21700 cells to try, but delivery of the battery I ordered has been delayed, not sure when I might get it. I need the battery to see if it performs OK if it does then I can plan to use that, otherwise it will need to be a 10S2P of 18650. With the battery chosen I can select the best battery\controller bag and work out all that's needed to move the bag onto the Brompton front carrier block and shorten all the cables and tidy the conversion up.
The current weight of eBrompton, with added rear rack, extendible wheels, Omni wheels and front and rear mudguards is 12.9Kg. If the 10S1P battery works OK, and with the changes related to the battery\controller bag are carried out, the final weight should, hopefully, be in the region of 12.5Kg.
I swapped out the rear Tanus airless tyre for a Continental Contact Urban air tyre with a Tubolito tube. Weight is around the same. The ride on the Continental Contact Urban is better, not so harsh.
Its a shame really, on normal cycle paths and good roads the Tanus is OK. The ride is not as good as an air tyre, but acceptable. With the Tanus there are no more punctures, no removing wheels when out and about nor the need to carry spares.
Many years ago when roads were kept in reasonable condition then Tanus airless tyres would have been OK in my locality. But in these modern times and with an overall national policy to apparently discourage cycling, road maintenance in my area seems to have been consigned to history.
Better tyres for front motor wheel
I previously had a problem with Continental Contact Urban tyres on the front motor rim. The rim appeared to be slightly different to a standard Brompton wheel rim and the Continental Contact Urban tyres would not hook into the rim properly. So I had fitted a Schwalbe Marathon plus on the front with a Continental Contact Urban on the back.
The Continental Contact Urban seems to have become the go for tyre on a Brompton, its light, apparently hard wearing and highly puncture resistant, see this video;
“I tour a lot, not had a flat in two years on the Brompton, in the thousands of miles, commuted to work, gravel paths, off road”
I wanted to have a handy spare tyre and when I found that the Continental Contact Urban folding tyres (from Brilliant Bikes) were cheaper (£28) and lighter (-44g) than the wired version I bought one. The wired version is £30 and a Schwalbe Marathon would be £37.50.
I decided to test fit the folding version of the Continental Contact Urban to the front motor wheel of eBrompton to see if I had the same problem as the wired version where the tyre bead comes off the rim on inflation.
The folding tyre was easy peasy to fit by hand, no tyre levers needed. Easy to get off too without levers so minimal risk of pinching the tube.
I inflated it to 90psi and it fits very well, nice and clean and even. Looks secure. I marked the edge of the tyre where it met the rim with a black marker all the way round on both sides of the tyre and removed it from the rim. I could see from the markings that the bead was evenly under the rim hook all the way around the tyre, good job.
Its rides well, at least in the dry, a bit smoother than the Marathon plus.
The front tyre I had previously fitted to eBrompton was a Marathon plus weighing 480g. The Continental Contact Urban folding is a mere 213g, so if these tyres are really as puncture resistant as the Schwalbe Marathons, then there is an overall weight saving on a Brompton for two tyres of 534g, cheaper too. Lets see how they last.
Adding the mudguards
The titanium button bolts arrived so it was time to add the mudguards. Ever since I started using a cycle for commuting, local shopping and touring rides, I have used full mudguards. Back in the day, circa 1977 I was the weirdo riding around on a custom Reynolds 531 double butted road racing cycle, fitted with full mudguards. I never have understood why so many cyclists go around on bikes that make them dirty when it rains.
The eBrompton mudguards are carbon, they don’t save much weight versus standard Brompton guards but they do look cool. The front mudguard stay is a titanium version. The rear mudguard is held in place by the rear rack.
The added weight of the mudguards, including stays, flaps and bolts was 177g.
Next steps
I was hoping that by now I would have a 10S1P battery of 21700 cells to try, but delivery of the battery I ordered has been delayed, not sure when I might get it. I need the battery to see if it performs OK if it does then I can plan to use that, otherwise it will need to be a 10S2P of 18650. With the battery chosen I can select the best battery\controller bag and work out all that's needed to move the bag onto the Brompton front carrier block and shorten all the cables and tidy the conversion up.
The current weight of eBrompton, with added rear rack, extendible wheels, Omni wheels and front and rear mudguards is 12.9Kg. If the 10S1P battery works OK, and with the changes related to the battery\controller bag are carried out, the final weight should, hopefully, be in the region of 12.5Kg.
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I don't understand the technicalities of how ebike charging systems work etc. I am able to buy kits and fit them myself though. I recently had an issue where thieves ripped the battery and cradle from the frame of my bike while it was D-locked. I was left with bolts holding bits of plastic to the frame, so a locking battery was useless.
I've now got a new 10ah battery and controller from Woosh as a replacement. This will be clamped to the Brompton stem using large jubilee clips. I will JB weld up the screw mechanism so that even I will need to cut them off in the fututre. They won't be removable with a screwdriver, so are kind of permanent.
However I would love to revisit the idea of using the Brompton as a shopping trolley. This would mean no longer leaving the bike outside while I shop. I tried it before but I thought it was far too clunky to use.
Can you advise which rack and Omni wheels you went with please? Do you have any links? My Brompton is a B75 and I added mudguards to it. So I need a rack that will fit regardless of the original specification. I'm not too obsessed with the weight either. Many thanks for the interesting read.
EDIT: I did a bit of searching and found this available in the UK. Looks very simialr to the one you have fitted but not sure it's the same.
www.londoncraftwork.co.uk
I've now got a new 10ah battery and controller from Woosh as a replacement. This will be clamped to the Brompton stem using large jubilee clips. I will JB weld up the screw mechanism so that even I will need to cut them off in the fututre. They won't be removable with a screwdriver, so are kind of permanent.
However I would love to revisit the idea of using the Brompton as a shopping trolley. This would mean no longer leaving the bike outside while I shop. I tried it before but I thought it was far too clunky to use.
Can you advise which rack and Omni wheels you went with please? Do you have any links? My Brompton is a B75 and I added mudguards to it. So I need a rack that will fit regardless of the original specification. I'm not too obsessed with the weight either. Many thanks for the interesting read.
EDIT: I did a bit of searching and found this available in the UK. Looks very simialr to the one you have fitted but not sure it's the same.
Lightweight rear rack for BROMPTON
Stylish rear rack for a BROMPTON bike. Compatible with any Brompton bike, with or without mudguards. Unlike the original Brompton rack, you do not need to change a rear mudguard. OPTION 1: Rack only OPTION 2: Rack + 2 x Easy Wheels (2 spare tyres included) OPTION 3: Rack + 4 x Easy Wheels (4...
www.londoncraftwork.co.uk
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Who takes their wheel off to fix a puncture? Not only is it a waste of time and very difficult when you have hub gears or a motor wheel, but it's completely unnecessary. I've fixed loads of punctures when I'm out and about, mainly on other people's bikes since I fitted Marathon Plus tyres, and I've never had to take any wheels off.
Turn the bike upside down; pull the tyre off one side; fix the puncture; remove whatever caused it; pull the tyre back on and pump it up. That takes about 6 minutes and you're on your way.
I dont normally fix punctures when out and about on the Brompton, I replace the tube with a spare, and then fix the puncture at my leisure.
Removing the Brompton 2 speed rear wheel is easy enough and the front motor wheel is no problem either.
I was not making a comment about repairing punctures in general and I would take a different approach on non-Bromptons.
That's daft. By the time you've got somebody to come and get you, or carried your bike to the bus stop, you could have fixed it and gone back to enjoying your ride.
Do a search on Aliexpress for 'Brompton Omni Wheels' they are a about £20 and some offer an apparently quieter upgrade for £30. Check the description to be sure they use metal pins for the roller bearings;
I have been on a number of shopping trips so far and they do make a big difference, its just so easy to push the Brompton arround. How long they last, who knows.
The Titanium rear rack I found on Aliexpress;
https://www.aliexpress.com/item/4000677748308.html?spm=a2g0o.order_list.order_list_main.139.44ee18024lEx8G
The rack you linked to does look very similar, it should fit as is to a Brompton. However, there are two types of mudguard on the Brompton, the L type with a roller wheel and stays and the R type for use with a rack. The bracket for the rear of the R type mudguard is on the rack by the lights, it does need to be in the right place.
You can find the standard Brompton rack on its own for around £70.
Agreed that would be daft.
Thats why I carry a spare tube, quicker to replace the tube than repair the puncture.
It isn't, and you can't replace a tube without taking a wheel off, and no need to tell me about those stupid Gaadi tubes which are more trouble than they're worth. Your argument is going around in circles. A patch repair takes minutes. A tube replacement means taking the wheel off, which isn't easy on a Brompton, whichever wheel it is, and you'd have to carry heavy tools, which negates all the work you've done to save weight. You'd need a substantial spanner for the motor wheel, another one for the rear wheel and something for the gear chain plus the weight of the tube. It doesn't really make sense after all that expense to save weight, when all you need is a 20 gramme puncture kit.
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All I need to remove both wheels, which on eBrompton I find easy, is a single 23g spanner.
Carrying a spare tube at a massive 39g, makes sense to me.
One thing you just maybe have a point about is that removing a standard 3\6 speed hub rear Brompton wheel can be a bit of pain for the inexperienced and can thus take a while, one of the reasons I dont use that setup for eBrompton.
You can get 25NM with a 23g spanner? I wouldn't like to meet you on a dark night.
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