TSDZ2 120mm Axle Broke for the 2nd time on my Fatbike

[casainho]

I installed at least 6 TSDZ2 motors bought on PSWPower and I never had any issue of that (100mm ones). I weight 105kgs and I always put my full weight on the pedals, I even calibrate the torque sensor for my full weight on each pedal.

Are you sure you got 100mm TSDZ2 spindles from pswpower.com? Their website is a mess. I've picked through it and every TSDZ2 listing (like this) states: "The Mid Drive Kits are designed to fit bikes with a 68mm (2.68 in.) or 73mm (2.87 in.) wide bottom bracket shell and 35mm inside diameter. " with no option to go bigger. I only find their Bafang BBSHD for 100mm. Do you have a direct link?

Sorry, I wanted to say the regular motor size.

 

[HerskerHans]

I've been looking into a way to mount a TSDZ2 on a fat bike. I only learned about future-bike.it in this thread, but there are others as you mention HerskerHans. You may find this useful to sort out the supply chains:

vendors.png

It looks like all the vendors are actually the same company apart from future-bike.it. Notice how the email addresses are shared.

Is it strictly future-bike.it spindles that are breaking? The important thing is that we avoid buying more spindles that come from the same factory that's making defective ones. It's important to find out if future-bike.it has any connection to the others w.r.t supply chain - otherwise you're just getting the same defective part.

Would everyone with a TSDZ2 who had a fat bike spindle break please say where they bought it?

Was anyone hurt? Which side is failing, left or drive side?

This is a safety critical failure. The bottom bracket spindle is most likely to snap while you're standing up on the peddles - then imagine that happening going down hill or at a high speed (which is usually the case when you're standing up).

https://www.eco-ebike.com/products/tsdz2-upgrade-bottom-bracket-axle-extension-in-92mm-100mm-120mm?fbclid=IwAR2ouMc3EPvAM8nHe5-67Emn9YM7bu19fI0Em997WnVU438tlTg6u74apCo

The pics don't show whether that spindle is the same, but when you view this video of it, it looks like it has the same cotter pin groove that the future-bike.it one has, so it apparently has the same weak point.

If they're going to use grooves for cotter pins, shouldn't they be using titanium?

It broke on the left side for me two times

 

[HerskerHans]

You've been a great help. So we know that it's not just 120mm spindles that are breaking.. it's also the 100mm ones. You've also confirmed that the defect is not just in future-bike.it, but also in the other shop chain.. so all supply chains are likely shipping bad spindles.

I installed at least 6 TSDZ2 motors bought on PSWPower and I never had any issue of that (100mm ones). I weight 105kgs and I always put my full weight on the pedals, I even calibrate the torque sensor for my full weight on each pedal.

How do you calibrate youre torque sensor? I do some light trail riding and jump over a few Stones in the woods, but i think the axle should handle it

 

[john61ct]

Would it be strong enough for heavy but slow, torque only for utility wheels stay on the ground except for riding over the occasional goat's head?

 

[HerskerHans]

Would it be strong enough for heavy but slow, torque only for utility wheels stay on the ground except for riding over the occasional goat's head?

Yes, i think so, i broke both mine in a jump where i compressed my full suspension half way down.

 

[Malitsuikka]

I have not been jumping etc at all.... just driving at forest ski tracks and trails.... some heavy hills I agree. It took 550 km to break BB100 spindle shaft.
By the way.... any idea where to buy BB100mm shaft.... I have not found locally (for reasonable price) and eBird store has not been answering to my questions.

 

[noviceBuilder]

By the way.... any idea where to buy BB100mm shaft.... I have not found locally (for reasonable price) and eBird store has not been answering to my questions.

See this post. There are only 2 sources, the Italian shop and the Chinese one. The Chinese source sells it through 3 different vendors, only one of which sells the spindle separately (the US shop).

They're all defective. The only way to avoid the defective 100mm spindles is to make your own.

 

[Malitsuikka]

Hi,
I ordered the extension kit fron Italian store.... don’t have it yet. Also I have sent several mails to chinese stores... no answers.
Quote for locally made (using manual machinery.... no automated NC machines) is rather high....too high.
I could live with the fact (as I have to) that shaft are breaking every now and then IF spare part pricing would be reasonable so that I could have couple of spindles always on my own inventory. Over 100€ Sparepart pricing (with shipping) does not meet that plan.

 

[noviceBuilder]

For the record, another spindle broke on someone else, who had a TSDZ2 on a cargo bike. I thought it should be linked in the thread herein.

Hi,
I ordered the extension kit fron Italian store.... don’t have it yet....Over 100€ Sparepart pricing (with shipping) does not meet that plan.

Would you mind saying what you were charged by the Italian store for the part and for the shipping? Their website is quite rough. I found this page but don't see a price.

 

[Malitsuikka]

For the extension kit (includes shaft, bearing, bushing etc) price is 89€ .... I asked also price for shaft only... it was 70€. Shipping was 20 so totally 109€.

 

[Malitsuikka]

About this problem. I measured that wall thickness at the point of failure is 3.1mm..... that is because of seger ring groove and hole (7mm) inside is not exactly at the centerline of shaft. Propably tip of the drill has been bending slightly during drilling. So, solid shaft at that point may not fix that for good but would be better than 3.1mm wall.
I have found (almost) local shop who has rather modern machinery and could make shaft for me. Material would be e.g. Moc 410 (42CrMo4) and solid at seger ring area. Would there be any interest for BB100 shafts for price around 65...70€ + shipping?
I’m asking as machining one only is not possible due to high initial costs. Warranty would be just as good as with chinese supplier .... nothing

Alternatively.... has someone already tried ”self made” improved shafts ....

 

[HerskerHans]

About this problem. I measured that wall thickness at the point of failure is 3.1mm..... that is because of seger ring groove and hole (7mm) inside is not exactly at the centerline of shaft. Propably tip of the drill has been bending slightly during drilling. So, solid shaft at that point may not fix that for good but would be better than 3.1mm wall.
I have found (almost) local shop who has rather modern machinery and could make shaft for me. Material would be e.g. Moc 410 (42CrMo4) and solid at seger ring area. Would there be any interest for BB100 shafts for price around 65...70€ + shipping?
I’m asking as machining one only is not possible due to high initial costs. Warranty would be just as good as with chinese supplier .... nothing

Alternatively.... has someone already tried ”self made” improved shafts ....

That is interesting, i just received mine from eco cycles. im sure im gonna brake this also, the hole is drilled to deep on this also. so it is basically the same as the stock one. hopefully better steel though. But if you make some, dont drill the hole passed the seger groove, it is not necessary.

 

[Balmorhea]

That is interesting, i just received mine from eco cycles. im sure im gonna brake this also, the hole is drilled to deep on this also. so it is basically the same as the stock one. hopefully better steel though. But if you make some, dont drill the hole passed the seger groove, it is not necessary.

I think you misunderstand how the stresses are distributed in this part. The stresses near the centerline are negligible, and the bolt hole makes little difference. The groove, however, places a stress concentration in the part at the location of highest stress. It probably has 1000 times more effect on the shaft’s tendency to break than the bolt hole.

 

[HerskerHans]

That is interesting, i just received mine from eco cycles. im sure im gonna brake this also, the hole is drilled to deep on this also. so it is basically the same as the stock one. hopefully better steel though. But if you make some, dont drill the hole passed the seger groove, it is not necessary.

I think you misunderstand how the stresses are distributed in this part. The stresses near the centerline are negligible, and the bolt hole makes little difference. The groove, however, places a stress concentration in the part at the location of highest stress. It probably has 1000 times more effect on the shaft’s tendency to break than the bolt hole.

Ok, but would a shorter bolt hole make it weaker or stronger? I want every strength i can i have in this poorly designed part. it can easily be drilled 10-15mm shorter, the bolt going in is short. Im not sure if this model is correct in real life either, the part doesn break under torque, it breaks when i land heavily after a jump on a trail. so the forces are acting straight down and stretching the top of the axle and compressing the bottom of the axle and it shears at the grove which is located at the bearing, creating a perfect breaking point.

 

[amberwolf]

All grooves like that are stress risers, and are where most shafts that break do so.

Freeze a 5lb chub of hamburger. Use a knife and score it in a circle halfway down. Whack the end on the ground...it'll snap at the groove, after enough hits, even if the groove was very shallow, and most likely will be a relatively flat shear plane (sometimes it's concave or convex).

Doesn't matter if you've drilled an axial hole in the end of the chub or not, to any depth you like--it'll still shear at that groove. (unless the chub collapses/crushes due to the fact it's not a solid material like steel, at the edges of the hole).

If there's other defects in the structure that are greater stress concentrators, you might get a breakage somewhere other than the groove first, but it's more than a fair bet that it'll shear there.


If there is any way at all to avoid such grooves, and use a different system to constrain lateral movement of the shaft or parts on it, I would always choose some other way to do it, if there is ever going to be any kind of radial torque on the shaft that's expressed across such a groove.

 

[Balmorhea]

Ok, but would a shorter bolt hole make it weaker or stronger? I want every strength i can i have in this poorly designed part.

A hole all the way through would probably diffuse stresses the most. But stresses along the axis are not significant compared to stresses on the outer skin.

If there’s enough room in between the bearing and the crank arm, using clamp collars instead of snap rings to retain an ungrooved spindle would give you the best chance of preventing spindle breakage.

 

[eyebyesickle]

I've been looking into a way to mount a TSDZ2 on a fat bike. I only learned about future-bike.it in this thread, but there are others as you mention HerskerHans. You may find this useful to sort out the supply chains:

vendors.png

It looks like all the vendors are actually the same company apart from future-bike.it. Notice how the email addresses are shared.

Is it strictly future-bike.it spindles that are breaking? The important thing is that we avoid buying more spindles that come from the same factory that's making defective ones. It's important to find out if future-bike.it has any connection to the others w.r.t supply chain - otherwise you're just getting the same defective part.

Would everyone with a TSDZ2 who had a fat bike spindle break please say where they bought it?

Was anyone hurt? Which side is failing, left or drive side?

This is a safety critical failure. The bottom bracket spindle is most likely to snap while you're standing up on the peddles - then imagine that happening going down hill or at a high speed (which is usually the case when you're standing up).

https://www.eco-ebike.com/products/tsdz2-upgrade-bottom-bracket-axle-extension-in-92mm-100mm-120mm?fbclid=IwAR2ouMc3EPvAM8nHe5-67Emn9YM7bu19fI0Em997WnVU438tlTg6u74apCo

The pics don't show whether that spindle is the same, but when you view this video of it, it looks like it has the same cotter pin groove that the future-bike.it one has, so it apparently has the same weak point.

If they're going to use grooves for cotter pins, shouldn't they be using titanium?

Hmm... close, but your chart is not 100% accurate, just to mention since you are sharing it...that may not be the best thing to do.

Eco Cycles (eco-ebike.com) does provide support
and advises various international distributors, and many of the same players are involved in the ebike trade, and have various deals and agreements, even joint projects.

If you want accurate information it may be more productive to simply ask, especially if you are sharing the information with others

 

[eyebyesickle]

By the way.... any idea where to buy BB100mm shaft.... I have not found locally (for reasonable price) and eBird store has not been answering to my questions.

See this post. There are only 2 sources, the Italian shop and the Chinese one. The Chinese source sells it through 3 different vendors, only one of which sells the spindle separately (the US shop).

They're all defective. The only way to avoid the defective 100mm spindles is to make your own.

Hi, sorry but this information is not correct.. can I ask how you came to this conclusion?

Regarding the 100mm extensions that are NOT from futurebike (futurebike uses a different material) I have seen more stock 68-73mm axles break than 100 or 120mm axles. Hard to say % wise, but as far as the numbers, it is actually pretty rare.

I think many things affect this, one is definitely the milling of the recessed line to accept the circlip. If this is not done correctly is production, it makes the weak point we many have noticed...

but to be clear, you are not completely accurate about the source or distribution, so it may be best not to make a statement like this when you are not sure.

As far as all the 100 and 120mm being defective, I think I know 100 users that would disagree with you... definitely room for improvement, just as with the stock axle, but I think it is misleading and wrong to make such a statement like this

 

[eyebyesickle]

Anyway, not to be abrasive, I just want to make sure everyone has accurate info, and that a company/product is not misrepresented.

FYI, I am the one that arranged the production of 100mm and 120mm bottom bracket extensions, AFTER futurebike has been doing it for a while. First futurebike did it, and while usually they are good, there was a couple problems for us.

I used to order from futurebike, and never had any axle/spindle break at first, then all of a sudden we had multiple breaks, right at the circlip groove in the spindle, so we think they machined the groove too much on a batch, and it was weaker. The design tongsheng made in the first place is not very good, to be honest, so if the groove is cut/milled too deep, it's very easy to snap. We noticed the extensions being made of a different/not consistent material. I'm no expert but I was worried it was weaker metal.

I still think the breaks come *mostly* from bad batches, but anyway, due to the above, slower communication, and the wholesale price, I went on to have some made myself, to send to an international partner, as well as our shop in US of course.

Now, of these that I had made, there have been a couple hundred sold between 100mm and 120mm extensions. Only a couple have broken from US sales (that I was contacted about/know of), and it is in the air if this was due to a bad installation of the extension piece, not due to the axle. As far as international sales, I have not heard of any, but it sounds like there may have been some incidents? Confirmation would be great. Over the past couple years, I have heard of maybe 10 of the stock 68-73mm axles/spindles breaking, FYI. In my experience, EVERY axle/spindle that has broken, stock, or extensions, have all been trail riders encountering drops. So, if the extensions have the same strength as the stock axle/spindle, I would not call them faulty, but this is not to say they cannot be improved, either... That being said, the TSDZ2 is not quite built to be used for trail riding etc, in my opinion.

If ANYONE broke an axle that was NOT from futurebike, please speak up, and give the conditions which it broke under. It looks like one person here mentioned this, and says they are having trouble with communication from Ebird. You can PM me and I can make sure your situation is addressed, as I have a good relationship with that company.

If this is a real problem that happens under typical riding conditions, or if I need to just due to the rate it is happening, I will see what we can do about making some of stronger material, and also possibly modifying the design.

From my perspective, with the data I have, I would not consider them faulty, which explains my above reply when someone stated that they are all faulty..., but of course I want to make sure I have as much data as I can obtain, and look to remedy the situation if they are in fact breaking.

Again, if anyone has purchased an extension that broke, which was NOT from futurebike, please share the specific info here, and let's see what can be done.

Sorry for the long messages, but I see this in an issue for the community, and I would like to fix it, and also clear up any misconceptions at the same time!

 

[HerskerHans]

here i break my second axle, both mine is from two different 100mm motor bought on aliexpress

[youtube]https://www.youtube.com/watch?v=rdSjb88jAXs&t=0s [/youtube]

ive broken two while trailriding. Retired my tsdz2 bike from the woods to the streets after breaking the second one. I weigh 95 kg.

 

[Lakus]

Sorry for the long messages, but I see this in an issue for the community, and I would like to fix it, and also clear up any misconceptions at the same time!

I have been lining up the parts needed to make my fatbike electric, but didnt find this thread before now. Ordered two TSDZ2's only hours ago, was about to order em3ev batteries when I stumbled upon this thread - making me a bit uneasy. I can deal with tinkering and replacing bits and bobs on the motor, but an axle breaking mid ride could result in a pretty bad situation.

In your opinion, what is the safest course of action here and what sellers are the most trustworthy? Im not going to be jumping or doing any spectacularly rough riding, but with the bike as my primary transport besides the regular bus/trainrides - and the broken axles in this thread - Im suddenly a bit more worried. Its not an insignificant amount of money to spend on something that might keep breaking.

I noticed that Eco-Cycles' product page says this: "D.I.Y Installation requires Tapping/Threading your TSDZ2 Axle Housing with a 30*2mm Tap". Is this the same for all extensions? This I do not have the equipment for myself.

 

[Balmorhea]

This is not a mysterious failure, nor one that can be overcome by sourcing parts from a reputable seller. The design of the TSDZ2 uses a spindle that's smaller in diameter than those used on any other bicycles, and then places a groove at the point of maximum local stress. What did they think was going to happen?

There's no fix for it. If you think there's a workaround for an inherently flawed and unsafe design, go ahead and think that. But there isn't. If you are smaller and weaker than any other cyclist, then maybe this part is right for you. If not, well, now you know what you're buying.

 

[Lakus]

Sucks, because the BBS 120mm extension costs the same as a new TSDZ2 motor, while not having any torque sensor stuff. I see people have been saying that someone need to make a TSDZ2/BBS hybrid for over 5 years, and Id agree :lol:

 

[arthurw]

I've had my 100mm TSDZ2 for about 8 months and 1200km, bought from Ebird on Aliexpress. It broke when landing a small jump. The point of failure is right on the circlip groove on the drive side. The motor is fitted to my Giant Trance dual suspension MTB. I ride trails with lots of roots and rocks.

Contacted Ebird and he sold me two spindles for the price of one, took 30 minutes to replace and now I have a spare.

I am hoping this spindle will last longer than the last.

 

[amberwolf]

Given the design flaw, it's not that likely.