Brompton with Tongxin 80mm reliablility

[Scoloplastic]

Hey guys,

First post for me after just viewing for about a month in this forum.

I started reading this forum shortly after buying an M3L Brompton and fitting it with a Tongxin 80mm (freedom).

So far the I am extremely happy with the setup, the bike is still light enough for me to get up 3 stories and move around with. The Engine is almost completely silent and has good torque and the final speed, though could be faster, fits exactly with the highest gear for pedaling.

I've started feeling concerned reading about the reliability of the motor in this forum though. From my understanding, the Tongxin motors do tend to last longer on smaller wheels, and I always make sure to pedal first and never pull the throttle from a stand still, and in general i always pedal on the highest gear when at full speed - combined with the fact that i am relatively light (73kg) i am hoping for a long lasting motor.

My daily commute is about 10miles round - the only issue is a 1-1.5 mile of cobbled road, that is uphill when on the way to work - so pedaling through it would defeat the purpose of getting to work sweat free.

Are there any people in this forum that have had the motor with small wheels under similar or rougher conditions for a long time an can report that the engine survived?

Or should I start planning ahead and think of a future Bafang conversion that from my understanding can last a lot longer?

Thanks!

 

[flecc]

The failures have been almost entirely on larger diameter wheels, especially the 700c (28") size and seem to be related more to torque strain from that lack of mechanical advantage than rough surfaces. They seem to be very suited to the 16" size, especially since the recommended 260 RPM version for that size in the UK leaves it assisting below the legal limit, more like 13/14 mph than 15 mph, giving a further mechanical advantage. I'm assuming you have that motor and not a higher RPM one of course.

 

[kitchenman]

I've got one in my CX700. THis is from the Cytronex web site:
"Currently, Cytronex is only suitable for surfaced routes, it is not suitable for bumpy off-road terrain. The precision roller drive has the advantage of being silent, smooth and very efficient, but it is not designed for the regular impacts experienced by off-road mountain bike use. Using the motor in these situations is not recommended and Cytronex may push you faster than would be comfortable in this terrain. We also recommend leaving the motor off on cobbled streets."

 

[Scoloplastic]

The failures have been almost entirely on larger diameter wheels, especially the 700c (28") size and seem to be related more to torque strain from that lack of mechanical advantage than rough surfaces. They seem to be very suited to the 16" size, especially since the recommended 260 RPM version for that size in the UK leaves it assisting below the legal limit, more like 13/14 mph than 15 mph, giving a further mechanical advantage. I'm assuming you have that motor and not a higher RPM one of course.

Thanks for the quick reply.

Yes it is the 260 RPM - so hopefully with the combination of always making sure I pedal first before using the throttle will give it an easier time so it will last a while according to what you're saying. I'll be sure to update the forum if otherwise.

 

[Scoloplastic]

I've got one in my CX700. THis is from the Cytronex web site:
"Currently, Cytronex is only suitable for surfaced routes, it is not suitable for bumpy off-road terrain. The precision roller drive has the advantage of being silent, smooth and very efficient, but it is not designed for the regular impacts experienced by off-road mountain bike use. Using the motor in these situations is not recommended and Cytronex may push you faster than would be comfortable in this terrain. We also recommend leaving the motor off on cobbled streets."

Yeah I read that about the Cytronex which is a part of why I worried, I am hoping this isn't the case for a 16" wheel with the 260 RPM motor though

 

[flecc]

I think the Cytronex fears are based on the Tongxin's unique spindle, it's in two parts so probably less strong than the usual one piece motor spindle.

It would probably be a good precaution to keep the tyre pressures at the lower end of recommended pressures.

I was going to recommend using a Schwalbe Big Apple tyre on the front since these are exceptionally shock absorbent, but sadly they only make them for the other 16" sizes, 305 and 355. Your Brompton uses 349 and they won't suit.

 

[Scoloplastic]

I think the Cytronex fears are based on the Tongxin's unique spindle, it's in two parts so probably less strong than the usual one piece motor spindle.

It would probably be a good precaution to keep the tyre pressures at the lower end of recommended pressures.

I was going to recommend using a Schwalbe Big Apple tyre on the front since these are exceptionally shock absorbent, but sadly they only make them for the other 16" sizes, 305 and 355. Your Brompton uses 349 and they won't suit.

Hmm.. that's too bad I guess. Thanks for the advice on the pressure though.

I have Schwalbe Marathon tyres - I lowered the front to 65PSI (60 is min) and the rear one to 75 - hope that will help.

 

[kitchenman]

I think the Cytronex fears are based on the Tongxin's unique spindle, it's in two parts so probably less strong than the usual one piece motor spindle.

It would probably be a good precaution to keep the tyre pressures at the lower end of recommended pressures.

I was going to recommend using a Schwalbe Big Apple tyre on the front since these are exceptionally shock absorbent, but sadly they only make them for the other 16" sizes, 305 and 355. Your Brompton uses 349 and they won't suit.

This is great Flecc. I actually know what your talking about! ..I hopefully will soon have a 12" 305 with a Big Apple tyre with a DAPUSH in the middle! which I understand is more robust than the Tongxin although a fair bit noisier .. Fortunately my wife likes milkmen so should find the noise soothing ...

 

[flecc]

I saw you were swapping to the 305, that's the nearest to a true 16" with tyre fitted. The 349 and 355 are nearer to 18" with tyres on.

 

[kitchenman]

I saw you were swapping to the 305, that's the nearest to a true 16" with tyre fitted. The 349 and 355 are nearer to 18" with tyres on.

Umm .. yeah .. would make a good pedelec quiz question ... when is a 16" wheel not a 16" wheel?

 

[flecc]

Umm .. yeah .. would make a good pedelec quiz question ... when is a 16" wheel not a 16" wheel?

Indeed, and the 700c rim is also a good one since it has two wheel sizes, To the sport crowd with their skinny slick tyres it's 27", but to utility and e-bikers with their fatter tyres it's a 28".

 

[jerrysimon]

We have been round this loop several times

I have a 1700 miles on my Tongxin and apart from an early scare when one of the springs was rubbing on the clutch all has been ok.

Regards

Jerry

 

[Scoloplastic]

I've got one in my CX700. THis is from the Cytronex web site:
"Currently, Cytronex is only suitable for surfaced routes, it is not suitable for bumpy off-road terrain. The precision roller drive has the advantage of being silent, smooth and very efficient, but it is not designed for the regular impacts experienced by off-road mountain bike use. Using the motor in these situations is not recommended and Cytronex may push you faster than would be comfortable in this terrain. We also recommend leaving the motor off on cobbled streets."

Sorry for bumping this thread - was just wondering though - does leaving the motor off on off roads\cobbled streets mean completely disconnecting it from the battery (I have no off switch) - or simply avoid using the motor in these parts?

Thanks,
Daniel.

 

[flecc]

It just means avoiding using it Daniel, no need to totally disconnect. It's drive force going through the rollers when on bumpy surfaces that has increased potential to damage.

 

[lemmy]

when is a 16" wheel not a 16" wheel?

I know that joke. When it's a jar?