Pre-conversion help/research

[dan3572]

Please excuse the bullets, I typed it on my pc then pasted!

• I’m considering the Bafang 36V 250 W BBS01-ETM although I am wondering whether I should consider a road legal Tongsheng kit instead?
• I wish to keep it legal.
• Reliability is important. My wife would struggle if she got stranded.
• The bike is a Kona Hei Hei 29er from about 2009, which I think should be an excellent base if the kits would fit (see pics).
• It’s my wife’s bike and the idea is to see if she can get out on it with me as she’s become disabled. We would like to go on easy trails minimising on-road but probably not single track. The hope is that if she runs out of energy she can use it as fully electric or a lot of assistance without fear of getting stranded.
• First question I suppose should be how do I check the kits will fit?
• Could I order the kit from China or another UK supplier rather than Brighton Bikes and what are the likely savings? Which non-UK suppliers are reputable and cheap?
• I’ve built non-electric mountain bikes in the past but not for several years so I’m a bit rusty on some of the technicalities.
• What chain line issues do I need to be aware of?
• The bike currently has a 3x9 Shimano XTR setup but with an SRAM rear cassette and with Shimano XT hydraulic brakes.
• Would the 9-speed rear cassette be suitable with say a 42T or 44T sprocket or would it be better to convert it to 1x11 or 1x12?
• Is an upgraded sprocket recommended?
• What about cranks? I’ve seen the ones that are supposed to correct offset issues and have heard the standard ones are poor. Should I factor these in, and which are recommended?
• Which controller is recommended and are they all programmable?
• I was planning on fitting the gear change controller.
• Some suppliers say about adding grease to the drive gears. Is there a how to on this if it’s recommended?
• Does adding a thumb throttle result in it being illegal? A friend has on fitted which he described as to help get started when required.
• What battery and mount should I be considering? How do I determine frame fit before buying?

Any help with this would be really appreciated. I'll be happy to record the build to help others.

 

[matthewslack]

Please excuse the bullets, I typed it on my pc then pasted!

• I’m considering the Bafang 36V 250 W BBS01-ETM although I am wondering whether I should consider a road legal Tongsheng kit instead?
• I wish to keep it legal.
• Reliability is important. My wife would struggle if she got stranded.
• The bike is a Kona Hei Hei 29er from about 2009, which I think should be an excellent base if the kits would fit (see pics).
• It’s my wife’s bike and the idea is to see if she can get out on it with me as she’s become disabled. We would like to go on easy trails minimising on-road but probably not single track. The hope is that if she runs out of energy she can use it as fully electric or a lot of assistance without fear of getting stranded.
• First question I suppose should be how do I check the kits will fit?
• Could I order the kit from China or another UK supplier rather than Brighton Bikes and what are the likely savings? Which non-UK suppliers are reputable and cheap?
• I’ve built non-electric mountain bikes in the past but not for several years so I’m a bit rusty on some of the technicalities.
• What chain line issues do I need to be aware of?
• The bike currently has a 3x9 Shimano XTR setup but with an SRAM rear cassette and with Shimano XT hydraulic brakes.
• Would the 9-speed rear cassette be suitable with say a 42T or 44T sprocket or would it be better to convert it to 1x11 or 1x12?
• Is an upgraded sprocket recommended?
• What about cranks? I’ve seen the ones that are supposed to correct offset issues and have heard the standard ones are poor. Should I factor these in, and which are recommended?
• Which controller is recommended and are they all programmable?
• I was planning on fitting the gear change controller.
• Some suppliers say about adding grease to the drive gears. Is there a how to on this if it’s recommended?
• Does adding a thumb throttle result in it being illegal? A friend has on fitted which he described as to help get started when required.
• What battery and mount should I be considering? How do I determine frame fit before buying?

Any help with this would be really appreciated. I'll be happy to record the build to help others.

A couple of recent threads. The first covers Bafang and TSDZ2 in links.

Help! - MTB frame criteria for Tongsheng TSDZ2?

Hello All Just joined this forum and my first posting is a request for help with an ebike build based on the Tongsheng TSDZ2. After several years of debating I recently took the plunge and purchased a Tongsheng TSDZ2 conversion kit with the intention of fitting it to my existing road bike...

www.pedelecs.co.uk

Review - Tong Sheng TSDZ2 Owner Survey

Apologies to those who may have read this survey on the Cycling UK forum but as there's no response so far (03May22), I'm posting here as I'm sure there will be greater interest. Intro • A bit of a long-ish read, but bear with me if you will – this is all about dispelling urban myth in favour...

www.pedelecs.co.uk

 

[Az.]

Why mid drive? You will loose front gears. I don't think it is a good choice in your case.
NIce bike

Throttle is legal, but there is a speed restriction.

 

[peter.c]

The bbs01 is the better option in that it requires less effort to gain assist you can ghost pedal the tsdz2 requires some [more] pedal effort
The etm provides [needs] 25 amps the same as a bbs02 36 500watt except the etm has the legal 250watt markings have owned both versions
But a standard bbs01 36v is set at 15 or 18 amps depends on the supplier which is more than enough for most legal uses also less current = longer range
Keep 9 speed and a 42t on the front might need a bling ring to get the chain line
The biggest problem i can see is fitting a battery in the triangle a piece of cardboard cut as a template will tell
But as rule of thumb if the fs frame is under 19 in it can be a head ache
My cube is a 19 .5 and had to get a custom 20 ah pack it has the bbs01 250watt max 12 amps 48v fitted

 

[StuartsProjects]

For a small frame triangle definetly check the fit of the battery. Whilst the outline of the battery might fit in the frame triangle, to remove\fit they need to slide up\down the mount and lift up a bit.

As and example, this is my conversion and although there seems to be plenty (?) of room around the battery there is not a lot of spare room when removing and fitting the battery.

 

[AntonyC]

Why mid drive? You will loose front gears. I don't think it is a good choice in your case.

For easy trails a well-chosen hub drive system could tick all your bullets except for solving the battery fitment issue. If you're limited to a bottle battery and your trails are steep (say 8%+) the battery current rating might become an issue, more so with hub drive.

 

[dan3572]

Thanks all.

I think I'll stick with mid drive as she used to do some trails up to about red grade so she might manage the odd bit of single track, and if it doesn't work out I could make better use of the kit on another bike.

It's a 19" frame IIRC. I'll start by measuring the space within the triangle and go from there.

 

[StuartsProjects]

You might see 36v\10ahr bottle batteries which although they look small they need a fait bit of space above the battery to remove\fit. I could not get a bottle battery to fit in the frame triangle of my bike (see previous picture).

 

[Woosh]

Please excuse the bullets, I typed it on my pc then pasted!

• I’m considering the Bafang 36V 250 W BBS01-ETM although I am wondering whether I should consider a road legal Tongsheng kit instead?
• I wish to keep it legal.
• Reliability is important. My wife would struggle if she got stranded.
• The bike is a Kona Hei Hei 29er from about 2009, which I think should be an excellent base if the kits would fit (see pics).
• It’s my wife’s bike and the idea is to see if she can get out on it with me as she’s become disabled. We would like to go on easy trails minimising on-road but probably not single track. The hope is that if she runs out of energy she can use it as fully electric or a lot of assistance without fear of getting stranded.
• First question I suppose should be how do I check the kits will fit?
• Could I order the kit from China or another UK supplier rather than Brighton Bikes and what are the likely savings? Which non-UK suppliers are reputable and cheap?
• I’ve built non-electric mountain bikes in the past but not for several years so I’m a bit rusty on some of the technicalities.
• What chain line issues do I need to be aware of?
• The bike currently has a 3x9 Shimano XTR setup but with an SRAM rear cassette and with Shimano XT hydraulic brakes.
• Would the 9-speed rear cassette be suitable with say a 42T or 44T sprocket or would it be better to convert it to 1x11 or 1x12?
• Is an upgraded sprocket recommended?
• What about cranks? I’ve seen the ones that are supposed to correct offset issues and have heard the standard ones are poor. Should I factor these in, and which are recommended?
• Which controller is recommended and are they all programmable?
• I was planning on fitting the gear change controller.
• Some suppliers say about adding grease to the drive gears. Is there a how to on this if it’s recommended?
• Does adding a thumb throttle result in it being illegal? A friend has on fitted which he described as to help get started when required.
• What battery and mount should I be considering? How do I determine frame fit before buying?

Any help with this would be really appreciated. I'll be happy to record the build to help others.

your triangle is too small for your solution.
Cut a piece of cardboard, 36cm L x 10cm H to see if it fits inside the triangle. That's the space needed for a typical 36V or 48V downtube battery. The ETM version is a name given to the BBS to denote that it has 25A maximum current. For that, you need at least a 15AH battery to avoid too much stresses. You can't have that much capacity in smaller cases for another 6 years at least.

 

[dan3572]

Thanks. Based on what's been said I'd go for the standard motor. The attached potos are based on the Eclipse template. One with a bit of a gap underneath to allow for the suggested 8mm. It looks like something custom might be needed.

 

[dan3572]

Maybe something like this

https://custombuilt-ebikes.co.uk/product/36v-12-5ah-small-triangular-bag-ebike-battery/

Hopefully it wouldn't affect the shift cable but I could work something out to solve that if necessary.

I'd like to maximise capacity though to reduce the risk of getting stranded due to the fatigue with which she suffers.

 

[Woosh]

a bag battery may work in your context (fair weather riding, little mileage) but in general, bag batteries are not lockable. You have to keep an eye on the bike all the time. Also, bag batteries are not protected against humidity. Water is the main issue for cells and electronics.

 

[dan3572]

Ah, ok. The one in the link would fit and the larger one probably would just about but I can't be certain. Otherwise a custom box might be the only solution unless the battery could be properly protected from humidity and water by some kind of wrap.

 

[Woosh]

Ah, ok. The one in the link would fit and the larger one probably would just about but I can't be certain. Otherwise a custom box might be the only solution unless the battery could be properly protected from humidity and water by some kind of wrap.

plastic wrap does not help, it retains humidity and accelerates corrosion. You need dry air insulation and space for any water that seeps into the case to collect and disperse/drain. That's why a good battery case is difficult to design. The Bosch batteries are excellent on this respect. A good battery remains safe even after 8-10 years. Not bags.
However, for a battery for fair weather riding, the risk is minimised.

 

[dan3572]

Got you. The bottom of the downtube would be a possibility but very exposed to water and dirt. Otherwise a custom hard case but where to find one/have one built that I can be sure will fit...

I could buy a different frame but if it can be done reasonably easily, this bike would be great, plus she likes it and is used to it.

Edit: insufficient clearance between bottom of downtube and front tyre anyway.

 

[Woosh]

full suspension bikes are difficult to convert anyway.

 

[dan3572]

In that I'm likely to run into additional problems? It's only 80mm travel in case that makes a difference.

 

[AntonyC]

your triangle is too small for your solution.

If the fatigue can hit hard i.e. exhaustion, you'd need a high capacity battery to make this work, and your wife would need to be OK with piloting her EV when it happens.

You could get a small battery to fit the triangle (or a seatpost rack), she'd ride that until empty, and you would carry a second and third for her to ride/waft home. Something like 36V tool batteries or cheap li-on soft-packs with DIY waterproofing.

But small => low current => mild performance, and the BBS01B might need programming to reduce the current. A different bike would make things easier.

 

[StuartsProjects]

The attached potos are based on the Eclipse template. One with a bit of a gap underneath to allow for the suggested 8mm. It looks like something custom might be needed.

Looks like plenty of space on the mostly flat top tube.

 

[Woosh]

Looks like plenty of space on the mostly flat top tube.

although the nose of most downtube batteries are tapered, they need 2cm free space in front to slide out of the rails. Also, the bottom side needs to be positioned above the chainring so that the chain can pass between the battery and the ring. His frame can only take a (36V 10.4AH) bottle battery, not the bigger HL, Polly, DP, shark cases.