Tongxin motor bearing longevity

[greyhound_dog_1]

Have found that about 6 months after purchase of Cytronex, the motorised front wheel doesn't freewheel as well as it used to. Particularly sluggish when cold - now in the second winter and I rotate the wheel by hand and it spins maybe 3 revolutions before stopping.

I'm informed by the guys at Cytronex that the motor bearings do degrade with time, but that they are sealed bearings and good quality. I should point out in fairness that my motor has been abused a bit of late, with deep puddles and a falling off accident, but even before all that it was degrading gradually over the first year of use.

Fortunately the motor is relatively cheap to service or replace, and the Cytronex team can repair these and turn them around same day. But I am just surprised that the freewheeling ability would degrade like this. My standard back wheel still spins fine, and has obviously been used under the same conditions.

The drag is such that the bike no longer rides like an unmotorised bike at high speed, it is very noticible, and the max range at full assistance is down from 10 miles to 6 miles which I put down to that rotational drag.

Seems like an annual post-winter bearing replacement is needed on this motor to keep it in good working order.

Just curious if other Cytronex owners have found the same thing, or is it just me?
What about other hub motor bikes? What about crank drives?

 

[Mark/Cytronex]

Have found that about 6 months after purchase of Cytronex, the motorised front wheel doesn't freewheel as well as it used to. Particularly sluggish when cold - now in the second winter and I rotate the wheel by hand and it spins maybe 3 revolutions before stopping.

I'm informed by the guys at Cytronex that the motor bearings do degrade with time, but that they are sealed bearings and good quality. I should point out in fairness that my motor has been abused a bit of late, with deep puddles and a falling off accident, but even before all that it was degrading gradually over the first year of use.

Fortunately the motor is relatively cheap to service or replace, and the Cytronex team can repair these and turn them around same day. But I am just surprised that the freewheeling ability would degrade like this. My standard back wheel still spins fine, and has obviously been used under the same conditions.

The drag is such that the bike no longer rides like an unmotorised bike at high speed, it is very noticible, and the max range at full assistance is down from 10 miles to 6 miles which I put down to that rotational drag.

Seems like an annual post-winter bearing replacement is needed on this motor to keep it in good working order.

Just curious if other Cytronex owners have found the same thing, or is it just me?
What about other hub motor bikes? What about crank drives?

I am somewhat mystified by this post because I am only aware of one customer contacting me about such a problem and you have owned your bike for a year and four months not 6 months, and we repaired your motor in December after you fell off and damaged it, and since we found water ingress due to you having been through a “lake” I said at the time that I could not guarantee the motor would not fail due to corrosion of the parts we did not replace (e.g. bearings). We can replace all parts but at a certain point it is more cost effective to replace the motor.

We care very much about our product which is why whenever anyone has an issue (whether an accident or otherwise) we get them back on the road very quickly because many of customers depend on their Cytronex bikes every day for work. We have many very high mileage commuters who have had no problems with their bearings or otherwise in the nearly five years since we started. I personally did more than 8,000 miles on my first Cytronex and the motor and original bearings were still going strong when I upgraded to a new Cytronex model.

 

[Deleted member 4366]

If it were me, I'd get one of these kits because they're very cheap. It should fit straight in and it's a lot less work than dismantling a Tongxin. The motor is very light and free-running. It can also take more abuse than a Tongxin. If it does give any problems, you can buy a spare bare motor which is even cheaper and replace the whole core and clutch - about 20 minutes work.
Measure the distance between your fork drop-outs to see whether you need the Q85 or Q100 (80mm vs 100mm). Assuming 36v:

Q100 36V250W-350W Front Driving E-Bike Kit - BMSBATTERY
Q100 36V250W-350W Front Driving EBike Hub Motor - BMSBATTERY

 

[TobyAnscombe]

Other than a light 'graunch' noise when I spin it backwards, mine has been fine. Currently on about 400 miles with road and light trail riding.

Yes, there is a slight drag but nowhere near as bad as you seem to have

 

[Jeremy]

I've stripped two Tongxin motors and have to say that it isn't really a DIY proposition unless you have access to (or can make) the ring distortion tool that allows easy reassembly. The tool is pretty much essential to get the outer drive ring back on, unless you want to faff about freezing the rollers and warming up the ring (which works, apparently, but I found fitting the ring easy with a home made ring distortion tool).

I doubt very much that it's the bearings themselves that are causing the extra drag, it's almost certainly coming from the internal one way clutch. If the motor has had water inside then I wouldn't be at all surprised to find that this has developed some corrosion.

As d8veh suggests, repairing a motor like this doesn't really make economic sense given that similar small motors are available for less than the cost of repairing the one you have. Also, the newer Tongxin design (the motors are available from Outrider) is supposedly somewhat more robust than the original, I believe. The only word of caution if you do decide you want another roller drive motor, like the original Tongxin, is that only the smaller, lower power, motor that Outrider sell has the roller drive, the 128mm diameter one has gears and is very similar to the Q100 that d8veh listed, and makes a fair bit more noise than the roller drive motor.

 

[wurly]

The one way clutches in these things have a habit of snatching the ball rollers and breaking the surrounding metal, which is very thin. There is a problem with the clutch which could be broken bits jamming something or maybe corrosion.



It's not difficult to inspect it, if, you can get the cover off. If you want to have a go, i can give you more guidance and if you need another clutch, JohnP (who never posts here) has got a box of spare parts from 'our' repaired tongxin motors. Pretty sure we have a couple spare clutches.
Although you can get another motor , it's a shame to scrap one if it can be fixed.
Getting the ring off the rollers is certainly tricky but i don't think you have to go that far...yet.

 

[jerrysimon]

This thread may prove interesting for those who want to see how to strip down a Tongxin.

http://www.pedelecs.co.uk/forum/electric-bicycles/5847-taking-tongxin-motor-apart.html#post75431

I actually find my Tongxin motors spin more freely as they age with use. The only problem I have had with them is the little springs in the rings sometimes come loose and make a terrible scratching noise when you rotate the wheel unpowered. Easily dismantled and fixed.

[video=youtube_share;SjT2bdWOm9M]http://youtu.be/SjT2bdWOm9M[/video]

I have never take the ring off the rollers, though as stated, there use to be a tool you could get from the supplier as shown in the thread I linked to above.


Regards

Jerry

 

[jerrysimon]

PS Just found this on youtube. Never seen a Tongxin motor like this before ?

[video=youtube_share;ymQyvh0L6iE]http://youtu.be/ymQyvh0L6iE[/video]

It seems to be a larger rear wheeled one ?

Also looks like a roller brake on the other side. Would be interesting to see the bike that wheel looks massive!

Hmmm interesting site they have with some interesting bikes including a powerful dual powered affair for getting up San Francisco hills!

http://www.hightekbikes.com/index.html

This looks like the bike

Ha ha its so funny where web surfing takes you lol

Time to go do some painting/DIY

Jerry

 

[Geebee]

That's not a roller brake it is a band brake, both lack braking ability in my experience but the band brake is far worse.

 

[jackhandy]

This thread is a classic example of the value of the forum (IMHO, of course).

Bloke has a problem - wants advice from other owners - dealer responds with no advice, just picks up a typo in the post & gets defensive about his product/service - experienced forum members offer advice & assistance.

Job done, the thread then beetles off on a tangent

 

[Jeremy]

Jerry,

That motor in the hightek photo is the forerunner of the Tongxin, the Tarn. They were sold here in a bike a bit like the one pictured, with small wheels (16" I think) but with suspension, called the Bliss. There's a thread on ES where an acquaintance, Neil Paisnel, stripped one down. Internally it's near identical to the Tongxin and probably came from the same university project, I think.

BTW, the tool for taking the ring off is fairy easy to make. All it does is distort the ring so that the roughly triangular profile of the rollers will fit in easily The only thing to remember is that the screw that pushes against the ring need to be midway between two of the rollers. I'm pretty sure that you could get the same effect by squeezing the ring in a vice, perhaps with a curved support on the single roller side, but only realised this after I'd turned up a bit of alloy to make the tool..................

 

[wurly]

I just had another thought about the lack of freewheeling ability.
It might be the two threaded nuts tight on the inner part of the sealed bearings. When the wheel nuts are tighened to keep the wheel in place, those nuts can be forced inwards too much causing pressure on the sealed bearings. Worth checking and backing them off 1/4 of a turn if they're too tight.

 

[jerrysimon]

That motor in the hightek photo is the forerunner of the Tongxin, the Tarn.

Thanks for the info Jeremy

Nice to know you have the tool

Though, to date, I have never had a ring go and I don't have access to spare rings anyway.

Ps taking a break in the DIY whilst the ceiling dries so I can give it a second coat.

Jerry

 

[Jeremy]

Thanks for the info Jeremy

Nice to know you have the tool

Though, to date, I have never had a ring go and I don't have access to spare rings anyway.

Ps taking a break in the DIY whilst the ceiling dries so I can give it a second coat.

Jerry

I'm not sure that you can still get rings, which may be the real problem if trying to repair one of these motors now. I got hold of some from a company in the Netherlands, who were selling a range of Tongxin spares a few years ago, and used them to fix a couple of motors from the first lot that arrived here in the UK, that had a fairly high failure rate.

The newer roller drive motors from either Keyde or Outrider may well be different internally.

 

[greyhound_dog_1]

This thread is a classic example of the value of the forum (IMHO, of course).

Bloke has a problem - wants advice from other owners - dealer responds with no advice, just picks up a typo in the post & gets defensive about his product/service - experienced forum members offer advice & assistance.

Job done, the thread then beetles off on a tangent

;-)

Yes and thanks all for the ideas on the motor alternatives. Having said that, it seems this just afflicts my motor and not generally the case for these tongxins.

As for ownership timescales, my post was not a typo, but perhaps badly explained.
Bought Oct 2011. April 2012, freewheel ability was slightly degraded (6 months use). Bought second charger due to reduced range. Freewheeling deteriotared gradually with time since then, as did range. Queried it with Cytronex last year, was told slight loss of freewheeling is to be expected with use.

Yes I fell off and knackered the motor freewheel in December 2012, about a week after cycling through a deep puddles, both of which I'm told contributed to that particular failure.

Hoped having Cytronex team switch out the freewheel components to get it working would also improve the freewheeling issue, so I was surprised to find it unchanged! Since this freewheel degredation started after about 6 months of use, and continues to get worse since then, it was not due to the accident or 'sub aqua cycling'. Hence I was curious if they all do this. But seems it is just mine.

I'll probably put up with it, run it another winter and get them to fit new bearings next year, if that is indeed the issue. Which I can only assume it is, as the freewheel/clutch internals were just replaced.

If I could steer the discussion slightly - robustness and well-engineered systems. Do they exist? i.e. Something you can cycle on 2000 miles a year, rain and snow, weatherproof motors that do not degrade and don't need maintenance every years. I'd be curious if people think hub or chain drive is best in that regard.

 

[jerrysimon]

Queried it with Cytronex last year, was told slight loss of freewheeling is to be expected with use.

Well as I said I have found the complete opposite to be true with my freewheel getting BETTER with use.

If I could steer the discussion slightly - robustness and well-engineered systems. Do they exist? i.e. Something you can cycle on 2000 miles a year, rain and snow, weatherproof motors that do not degrade and don't need maintenance every years. I'd be curious if people think hub or chain drive is best in that regard.

My original Brompton is three years old with 4500 miles on the Tongxin which has been ridden pretty much every day of my work commute, I don't ride in snow and ice. I do ride in torrential rain but have never submersed the hub

By far the higher maintenance is with the bike itself, cleaning the muck off replacing chain, sprockets, brake blocks etc

Regards

Jerry

 

[greyhound_dog_1]

Well as I said I have found the complete opposite to be true with my freewheel getting BETTER with use.

Thanks for the info Jerry. In any case, your experience gives me confidence that I could have the motor replaced with another Tongxin at some point, it probably wouldn't happen again. Unless it is due to using it in rain, sub zero conditions and storing it in an unheated shed.

I do like the silent drive, I wouldn't have it any other way. I'll try and put up with it...it still gets me to work and back okay, until such time as it does not then I will get it fixed again.

 

[flecc]

;-)
If I could steer the discussion slightly - robustness and well-engineered systems. Do they exist? i.e. Something you can cycle on 2000 miles a year, rain and snow, weatherproof motors that do not degrade and don't need maintenance every years. I'd be curious if people think hub or chain drive is best in that regard.

The Panasonic crank drive units have a very good record in this respect. The original version introduced in 2001 mostly run trouble free with many still running in regular use to this day. Mechanically it was over-engineered but a very few units did have the odd electronic problem, mainly of one type. The current unit which replaced the original for 2007 dealt with the few known issues and of the many thousands of units produced I've only heard of one internal fault. There have however been a few transmission faults external to the unit, mainly in the form of chain jumping problems due to the chain idler arrangements, particularly with derailleur gears where the rear mechanism tensioner can conflict with the front chain path components.

At its best in applications like that on the Kalkhoff Agattu where the new standard Panasonic unit is coupled to a Shimano Nexus 8 or 11 speed gear hub, they tend to be unfailingly reliable long term. Added to that, the Panasonic made 10 Ah battery that most e-bike makes using this unit are supplied with has been running trouble free into a fourth year of life, unusual among lithium batteries.