Advice required on a brompton conversion
- Thread starter slippa
- Start date
Oh my god - this is awesome. I still have a huge grin on my face.
I just went out for a quick spin and it pulls me at 22/23.5mph (23.5 according to the CA and 22mph according to the speed camera/display we have down the road). I can easily get up to 27mph when pedalling fast and if I changed to the 54t chainset, I 'd have no problem hitting 30mph.
The hill I hit on my way back from work was no problem at all. I sailed up it in low with very little effort.
The motor and controller are barely warm. I have the controller limited to 10A and I think I'll leave it at that as the speed is more than adequate.
Thanks all for all your help and advice. I'll take some pictures today and post.
Cheers
Matt
I just went out for a quick spin and it pulls me at 22/23.5mph (23.5 according to the CA and 22mph according to the speed camera/display we have down the road). I can easily get up to 27mph when pedalling fast and if I changed to the 54t chainset, I 'd have no problem hitting 30mph.
The hill I hit on my way back from work was no problem at all. I sailed up it in low with very little effort.
The motor and controller are barely warm. I have the controller limited to 10A and I think I'll leave it at that as the speed is more than adequate.
Thanks all for all your help and advice. I'll take some pictures today and post.
Cheers
Matt
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Great, sounds awesome, glad to have been able to help someone else after all my dumb questions !
(Just got to build my own now)
Hello Slippa,
Nice work with your Brompton!!
So you have a 36V350W front motor with a 48V battery? (from Cellman?). And you can reach 22.5mph on it?
According to the simulator, the BPM 36V500W would be around 18.6 mph at this voltage:
So your bike is quite faster than what is expected from the simulator on a Brompton. Maybe the rear BPM 36V500W at 393 RPM is slower?
Nice work with your Brompton!!
So you have a 36V350W front motor with a 48V battery? (from Cellman?). And you can reach 22.5mph on it?
According to the simulator, the BPM 36V500W would be around 18.6 mph at this voltage:
So your bike is quite faster than what is expected from the simulator on a Brompton. Maybe the rear BPM 36V500W at 393 RPM is slower?
If it's a Q85 I think Slippa you're playing with the limit of the motor at 500W. I'd say 300-400W continuous would be a much safer place for this little motor.
A member had his Q85 melted after 250km at 420W continuous and 640W peak with this motor lol
A member had his Q85 melted after 250km at 420W continuous and 640W peak with this motor lol
Hi
Im looking into having a Nano motor fitted they open up the xtg forks a bit battery is in bottom of a new decent bag that fits on the front carrier and auto connects to the motor good article in a to b ive seen costs £900! fitted
Im looking into having a Nano motor fitted they open up the xtg forks a bit battery is in bottom of a new decent bag that fits on the front carrier and auto connects to the motor good article in a to b ive seen costs £900! fitted
Hi All
On another run yesterday, I managed 25mph according to the road speed camera and display - but that was with some pedalling on approach to it and then using the motor to maintain the speed as I passed it.
I've just re-measured the circumference of my tyre and I did have it set in my CA to 1345mm when it it actually 1300mm but that only accounts for 1-2mph (which explains why my CA was reading 23.5mph on my first run yesterday when the the road speed camera and display said 22mph). Under no load/freewheeling, the CA now says the wheel is running at 29.9mph.
My CA reports my 48V 9.5Ah battery as 51.3V and when the motor is under strain and at full throttle, it drops to 46/47V and it shows it's using around 480W. I don't sustain this hammering of the motor so I'm not too concerned right now. The motor doesn't seem to be getting hot at all (not like it did when i had the hall wires mixed up).
On another run yesterday, I managed 25mph according to the road speed camera and display - but that was with some pedalling on approach to it and then using the motor to maintain the speed as I passed it.
I've just re-measured the circumference of my tyre and I did have it set in my CA to 1345mm when it it actually 1300mm but that only accounts for 1-2mph (which explains why my CA was reading 23.5mph on my first run yesterday when the the road speed camera and display said 22mph). Under no load/freewheeling, the CA now says the wheel is running at 29.9mph.
My CA reports my 48V 9.5Ah battery as 51.3V and when the motor is under strain and at full throttle, it drops to 46/47V and it shows it's using around 480W. I don't sustain this hammering of the motor so I'm not too concerned right now. The motor doesn't seem to be getting hot at all (not like it did when i had the hall wires mixed up).
Some pics as promised
My controller and wiring is stashed in this nylon bag (its the bag to an old British Airways supplied Power Adapter for Laptops (before they switched to the U.S Power socket)
My Battery stored in the font bag. Note the B&Q quick release plug and socket similar to those on Electric power tools/lawnmowers.
The motor's spec on the sticker.
The motor in the wheel. I need to switch the tyre to my Marathon one.
The CA showing the top speed of the wheel under no load.
My controller and wiring is stashed in this nylon bag (its the bag to an old British Airways supplied Power Adapter for Laptops (before they switched to the U.S Power socket)
My Battery stored in the font bag. Note the B&Q quick release plug and socket similar to those on Electric power tools/lawnmowers.
The motor's spec on the sticker.
The motor in the wheel. I need to switch the tyre to my Marathon one.
The CA showing the top speed of the wheel under no load.
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Hey cwah - could it be that the 16" wheel the simulator is referring to is the 317mm version rather than the 349mm used on the brompton?
My 16 x 1 3/8 349mm tyre has a circumference of exactly 1300mm.
The Cycle Analyst manual has a table of circumferences for popular tyre sizes and suggests the following:
16 x 1.50 ~ 1185mm
16 x 1 3/8 ~ 1282mm (18mm less than my measured circumference!)
So that's 97mm (7.6%) difference which should have an effect on overall top speed.
Either way, all I can tell you is that it flies and if my CA is not configured correctly, neither is the speed camera down the road.
Cheers
Matt
My 16 x 1 3/8 349mm tyre has a circumference of exactly 1300mm.
The Cycle Analyst manual has a table of circumferences for popular tyre sizes and suggests the following:
16 x 1.50 ~ 1185mm
16 x 1 3/8 ~ 1282mm (18mm less than my measured circumference!)
So that's 97mm (7.6%) difference which should have an effect on overall top speed.
Either way, all I can tell you is that it flies and if my CA is not configured correctly, neither is the speed camera down the road.
Cheers
Matt
Hello Slippa,
Nice work with your Brompton!!
So you have a 36V350W front motor with a 48V battery? (from Cellman?). And you can reach 22.5mph on it?
According to the simulator, the BPM 36V500W would be around 18.6 mph at this voltage:
So your bike is quite faster than what is expected from the simulator on a Brompton. Maybe the rear BPM 36V500W at 393 RPM is slower?
Hello matt,
Sorry I thought it was a bpm. If it's a cute that's normal, it's another motor.
I hope this little Q85 is going to have a long live, otherwise, it would be an opportunity for you to upgrade it to a cute100 or 128
Sorry I thought it was a bpm. If it's a cute that's normal, it's another motor.
I hope this little Q85 is going to have a long live, otherwise, it would be an opportunity for you to upgrade it to a cute100 or 128
Another possible source for Brompton rims 16" x 1.375", made in Taiwan - they even look like standard rims!
Bicycle Wheel Traditional Spoke Rim - Buy Bicycle Wheel Traditional Spoke Rim Product on Alibaba.com
Bicycle Wheel Traditional Spoke Rim - Buy Bicycle Wheel Traditional Spoke Rim Product on Alibaba.com
A short update:
I've blown up my CA! I think I tore the speedometer cable and in an attempt to check the voltage across the pads it connects to, my multimeter probe slipped and there was a bang and a bit of burning
I contacted Justin who gave me some instructions to determine whether it is worth saving and what do you know - I made it bang and smoke some more! Justin was very understanding and offered me a good deal on a replacement which I've jumped at.
In the meantime, I've been having lots of fun keeping up and finally leaving behind several lycra-clad chaps who appear to be quite put out by my little Brompton ;-) I also upgraded my crank to the 54t version to ensure the cadence is more manageable and appears less comical. Tip for those considering it - you'll obviously need a longer chain (I needed the 102 link) but make sure you change the rear sprockets at the same time! I didn't do it initially and I couldn't figure out why the chain kept slipping. I then realised that the sprocket and chain had worn and stretched together such that the new chain no longer meshed with the old sprocket teeth.
Am considering adding the following:
Replacement for the crappy brompton gear shift. I'd prefer a left-hand version but they don't seem to do one and I'm unsure whether a shimano one would be compatible with the SA hub:
http://www.sjscycles.co.uk/sturmey-archer-dls30-trigger-for-3-speed-hsj951-prod19287/
Air horn to warn the many twits who blindly walk out in front of me. The annoying thing is they have been doing it when I'm not even using the motor but you can guarantee that if I did hit one of them they'd argue that I was using it and traveling too fast:
http://www.sjscycles.co.uk/delta-air-zound-3-rechargeable-air-horn-prod3/
I've blown up my CA! I think I tore the speedometer cable and in an attempt to check the voltage across the pads it connects to, my multimeter probe slipped and there was a bang and a bit of burning
I contacted Justin who gave me some instructions to determine whether it is worth saving and what do you know - I made it bang and smoke some more! Justin was very understanding and offered me a good deal on a replacement which I've jumped at.
In the meantime, I've been having lots of fun keeping up and finally leaving behind several lycra-clad chaps who appear to be quite put out by my little Brompton ;-) I also upgraded my crank to the 54t version to ensure the cadence is more manageable and appears less comical. Tip for those considering it - you'll obviously need a longer chain (I needed the 102 link) but make sure you change the rear sprockets at the same time! I didn't do it initially and I couldn't figure out why the chain kept slipping. I then realised that the sprocket and chain had worn and stretched together such that the new chain no longer meshed with the old sprocket teeth.
Am considering adding the following:
Replacement for the crappy brompton gear shift. I'd prefer a left-hand version but they don't seem to do one and I'm unsure whether a shimano one would be compatible with the SA hub:
http://www.sjscycles.co.uk/sturmey-archer-dls30-trigger-for-3-speed-hsj951-prod19287/
Air horn to warn the many twits who blindly walk out in front of me. The annoying thing is they have been doing it when I'm not even using the motor but you can guarantee that if I did hit one of them they'd argue that I was using it and traveling too fast:
http://www.sjscycles.co.uk/delta-air-zound-3-rechargeable-air-horn-prod3/
Yep the old sprocket new chain caught me out recently too, even though I changed the chain after only 1000 miles/10 months use (makes a note to clean it down more often). The trick is to buy a change wear tool and test it and change the chain before it wears out the sprocket.
Mind you at only a few pounds/rear sprocket it won't break the bank. The main chain ring is a different matter though.
I now have 54T mains on both my Bromptons. One is an auto change two speed hub which gives me 56" and 77" gears and the other the standard Bronmpton two speed which gives 56" and 74" gears.
This keeps cadence comfortable up to around 20-23mph which I rarely exceed.
Regards
Jerry
Mind you at only a few pounds/rear sprocket it won't break the bank. The main chain ring is a different matter though.
I now have 54T mains on both my Bromptons. One is an auto change two speed hub which gives me 56" and 77" gears and the other the standard Bronmpton two speed which gives 56" and 74" gears.
This keeps cadence comfortable up to around 20-23mph which I rarely exceed.
Regards
Jerry
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Ordered, received and fitted both the 3-speed gear trigger and the Air Zound horn and can highly recommend both.
The Gear trigger is so much quicker and easier than the stock Brompron gear shift but it did require I move my thumb throttle to the Left-hand side of the handlebars.
The Air Zound is very loud and I'm looking forward to alerting both pedestrians and cars to my position. It can be adjusted to be slightly quieter which would be my preferred setting when alerting pedestrians (as it really does make you jump!) but the louder option could be useful for those in Noisy Diesels/Lorries with their radios blaring. I haven't settled on a position for the bottle yet and have just secured it to the stem with the supplied Velcro and cable ties.
The Gear trigger is so much quicker and easier than the stock Brompron gear shift but it did require I move my thumb throttle to the Left-hand side of the handlebars.
The Air Zound is very loud and I'm looking forward to alerting both pedestrians and cars to my position. It can be adjusted to be slightly quieter which would be my preferred setting when alerting pedestrians (as it really does make you jump!) but the louder option could be useful for those in Noisy Diesels/Lorries with their radios blaring. I haven't settled on a position for the bottle yet and have just secured it to the stem with the supplied Velcro and cable ties.
Attachments
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I am reviving the - very old indeed- thread hoping that slippa or someone else with experience with the motor can comment on the installation, especially on the length of the axle - from the photos it seems to be extremely long- and how does this affect the fold.
Spreading forks and dropout grinding is the same as with the tongxin apparently, they have the same axle diameter and case dimensions.
I 'll order the 201 rpm version, i need only assistance uphill, motor will not be used on flats.
Controller the S06S from BMS bat. i ' ll get the sensorless version too -S06P- to give it a try.
I am building the battery now, 2 5s 5ah lipos with 2 cellog 8s, a couple of relais and voltage regulators for low voltage and cell drift protection. Total weight 1,6 kg.
I' am waiting for the sun rim to arive to measure the exact erd and order spokes, i hope the lbs in the neighbourhood will built the weel for me.
Greetings,
Konstantinos
Spreading forks and dropout grinding is the same as with the tongxin apparently, they have the same axle diameter and case dimensions.
I 'll order the 201 rpm version, i need only assistance uphill, motor will not be used on flats.
Controller the S06S from BMS bat. i ' ll get the sensorless version too -S06P- to give it a try.
I am building the battery now, 2 5s 5ah lipos with 2 cellog 8s, a couple of relais and voltage regulators for low voltage and cell drift protection. Total weight 1,6 kg.
I' am waiting for the sun rim to arive to measure the exact erd and order spokes, i hope the lbs in the neighbourhood will built the weel for me.
Greetings,
Konstantinos
If the motor is the same width as the Tongxin narrow version (80mm), then it should be easy enough to fit.
The forks will easily spread to accomodate the motor though with the Tongxin you have to put some spacers on one side to centre it correctly.
The only other challenge is to enlarge the mudguard stay to fit over the larger motor shaft and fit rubber cover over the wire exit as it then won't clip over the rear stay. I tend to discard the rubber bung and just wrap it up in self emagulating waterproof tape.
I fitted a Tongxin to the Brompton Ti forks which took about four times as long both grinding the Ti dropouts wider and trying to spread the forks!
Ps can you get the motor with 28H drilling as that makes things much easier in that you can use the standard Brompton double walled rims. The Sun rims are a pig to get tyres on. Build wise have you consired using radial spoking (no crosses) which make it really easy ?
Regards
Jerry
The forks will easily spread to accomodate the motor though with the Tongxin you have to put some spacers on one side to centre it correctly.
The only other challenge is to enlarge the mudguard stay to fit over the larger motor shaft and fit rubber cover over the wire exit as it then won't clip over the rear stay. I tend to discard the rubber bung and just wrap it up in self emagulating waterproof tape.
I fitted a Tongxin to the Brompton Ti forks which took about four times as long both grinding the Ti dropouts wider and trying to spread the forks!
Ps can you get the motor with 28H drilling as that makes things much easier in that you can use the standard Brompton double walled rims. The Sun rims are a pig to get tyres on. Build wise have you consired using radial spoking (no crosses) which make it really easy ?
Regards
Jerry
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