Tsdz2 bottom bracket / crank spindle bearings

[I_Like_Pedalling]

Hi, sorry I've searched but failed to find anything.

I have a 36v 250w on stock firmware with UK legal low speed limiter. I've done 4500km never opened, used on road and gentle off-road all seasons for a year since fitting on a old FS MTB.

There is play/wobble developing in the bottom bracket/pedal spindle bearings.

There are two topics to my question.

1. Is there any real risk if I ignore it until the cranks hit the frame like I have traditionally done with manual bikes in the past.

2. What bearings do I need to order and is there a DIY guide to changing them somewhere. Will the spindle itself be ok to go again.

It's in daily pottering about use for both transport and liesure, so I would rather take it apart with the new bits ready to go back in straight away.

Many thanks

 

[I_Like_Pedalling]

Clearly I didn't search hard enough...

From the wiki:

Main pedal shaft: left side 6902RS (61902 2RS1) – right side on torque sensor HK 2212 (note: on left side it is beneficial to put two bearings instead of one)

Other than the above part numbers I think my original 2 part question would still be useful if people have insight and or DIY guide links.

 

[Chalo]

Note that both the spindle diameter and the crank bearings of TSDZ2 are smaller and weaker than any other commercial bottom bracket parts available anywhere.

If you depend on an e-bike for transportation, best have a hub motor bike available even if it's not your first resort. TSDZ2 is one of your least reliable options for an e-bike.

Having used a BBS02 for years, at this point I would only use a crank drive on a play bike, and not on a bike I actually need to get around. And BBS02 is much more reliable than TSDZ2.

 

[I_Like_Pedalling]

Haha I suspected that the tdsz2 wouldn't be the height of ruggedness! I do have a car as well so downtime doesn't stop me getting to work etc. Just I really like biking everywhere so try to keep 'frankenbike' in a working state as much as possible! :+)

 

[endlessolli]

Clearly I didn't search hard enough...

From the wiki:

Main pedal shaft: left side 6902RS (61902 2RS1) – right side on torque sensor HK 2212 (note: on left side it is beneficial to put two bearings instead of one)

Other than the above part numbers I think my original 2 part question would still be useful if people have insight and or DIY guide links.

Regarding some information on improving / repairing your system:

I would leave the bearings in there as they are, but add additional 6902RS's - one on each side of the shaft - as a replacement of the outermost shaftseals. This is a common cheap&easy improvement against wobble / play on the TSDZ2 and also helps the to support the shaft better.

I don't find the respective forum entries about this improvement - but this is described in this forum somewhere.
(Also user @Elinx has a perfect overview about all TSDZ2 topics in here... hopefully he reads this and can help with links..)
Good Luck!

 

[Elinx]

....
From the wiki:

Main pedal shaft: left side 6902RS (61902 2RS1) – ...... (note: on left side it is beneficial to put two bearings instead of one)

.... still be useful if people have insight and or DIY guide links.

Here is the "how to" from me.
It will give some improvement, because you support the shaft on more places.
But in your case with 4500km, the shaft and spragclutch will have problably already more wear. So I think all the play won't be gone
The wobble comes mostly from the spragclutch, but with a bearing inside the spider instead of that flexible rubber seal, you reduce the movement of it.
It is even possible to add three extra bearings for maximum support of the shaft, if you replace both rubber seals for a bearing.

 

[I_Like_Pedalling]

Excellent, thank you both!

I've read Elinx's guide and ordered an additional 3 support bearings

 

[Elinx]

... ordered an additional 3 support bearings

Don't forget the rubber O-rings against water ingress, sandwiched between the inner ring of these outer bearings and the cracks.
I have used 14.5mm because the shaft is a tiny bit smaller than 15mm.

 

[ornias]

Note that both the spindle diameter and the crank bearings of TSDZ2 are smaller and weaker than any other commercial bottom bracket parts available anywhere.

If you depend on an e-bike for transportation, best have a hub motor bike available even if it's not your first resort. TSDZ2 is one of your least reliable options for an e-bike.

Having used a BBS02 for years, at this point I would only use a crank drive on a play bike, and not on a bike I actually need to get around. And BBS02 is much more reliable than TSDZ2.

with the extra spindel support documented above and/or filling the grove, I don't see how it's less reliable in that state. It would be pretty-hard to distort the spindle enough to break things that way. As the lever and play get a lot smaller.

 

[Elinx]

....
with the extra spindel support documented above and/or filling the grove, I don't see how it's less reliable in that state. It would be pretty-hard to distort the spindle enough to break things that way. As the lever and play get a lot smaller.

Imho Chalo is right about the reliability differences between BBSxx and Tsdz2.
But you have to accept that if you want torque sensing for a reasonable price.

With relative easy additions to the Tsdz2, like OSF for better power handling, extra bearings on the shaft and thermoconductive materials between bare motor and housing to reduce overheating, you can improve that reliability, but it shouldn't be neccesary.

For MTB use, the spindle grooves are still a weak point if you do jumps standing on the pedals.
This was certainly the case with the extended 100-120mm shaft.
I don't know if extra bearings on the other side of that groove will be sufficient which such use.

 

[ornias]

you can improve that reliability, but it shouldn't be neccesary.

Agreed though

For MTB use, the spindle grooves are still a weak point if you do jumps standing on the pedals.

Also agreed, but I think with a good metal bonding epoxy (like Loctite Metal/Concrete, with a tensile shearing strength of 3000+psi) And extra bearings, I don't see how enough shear force would be applied to the grove to still shear.

In my opinion the addition of strong epoxy essentially provides somewhat of the same extra stability that rounded corners would've supplied and the additional bearing, would put put the lever point significantly cluster to the crankarm AND provide better load spreading as well.

*edit*
I'm currently enquiring how much it would cost to have a small-batch production done in europe...

 

[Chalo]

I think with a good metal bonding epoxy (like Loctite Metal/Concrete, with a tensile shearing strength of 3000+psi) And extra bearings, I don't see how enough shear force would be applied to the grove to still shear.

The spindle doesn't fail in shear; it fails in bending. Also, with any adhesive you use to fill the groove having at least ten times less strength and elastic modulus than the steel in the spindle, it would be about the same as leaving the groove empty. Like trying to repair a cracked sidewalk with pancake batter.

 

[ornias]

I think with a good metal bonding epoxy (like Loctite Metal/Concrete, with a tensile shearing strength of 3000+psi) And extra bearings, I don't see how enough shear force would be applied to the grove to still shear.

The spindle doesn't fail in shear; it fails in bending. Also, with any adhesive you use to fill the groove having at least ten times less strength and elastic modulus than the steel in the spindle, it would be about the same as leaving the groove empty. Like trying to repair a cracked sidewalk with pancake batter.

I already found that out by looking into the steel strength to get some fixed variants made. But thanks for the headsup anyway ^^

 

[I_Like_Pedalling]

My use case is well clear of the how strong is it discussion above! (disabled cyclist with weak ankles so no jumping!).

Anyway I can report the additional support bearings have reduced the amount of wobble, probably about half as wobbly now. 5minute job and I'm happy with the result. Hopefully it can keep going a little longer before any significant overhaul is needed.

Thanks folk

 

[Elinx]

... the additional support bearings have reduced the amount of wobble, probably about half as wobbly now. ...

That was expected, with that number of km's there must be some wear already.

The bearing is inside 15mm, but the Tsdz2 spindle is about 14.9mm and if there is some wear maybe less.
Loctite 641 (or brass shims) between spindle and inner bearing could help a bit too.

 

[I_Like_Pedalling]

I'm happy with it now tbh

If someone really cared about getting rid of the last bit of play one other method could be a pair of Speedi Sleeves. I found one for 14.96 to 15.06, but at £21 +20% VAT each I decided I could live with a little bit of residual wobble!

 

[I_Like_Pedalling]

These things:

https://www.skf.com/uk/products/ind...smission-seals/wear-sleeves/skf-speedi-sleeve

 

[Elinx]

... £21 +20% VAT each...

You are right not to invest in this, because you never be sure it will fit.
Retaining compound, epoxy glue or brass shim sheats are a lot cheaper.
You only have to cut what you need.

 

[astronaut]

I've done 4500km never opened

Cool! 4500 km is impressive because I’ve only done 40 km on z2b model and already see play in the axle. Now I’ve started reading more reviews, and I’m shocked at how unreliable this motor is.. need to add extra bearings, lubricate almost every 500 km (but even so, the torque sensor or clutch will break after 1000-2000 km) and so on.

 

[castor57]

5000km on my tzd2b in hilly norther Spain, eurovelo 3 (el Camino) and velosud in France from st jean de Luz to perpignon and it's still going. No mods or maintenance done, save straighter crank arms and a 38t chainring in a Rans recumbent, 120 kg rider. So I wouldn't say they are all unreliable or high-maintenence.

 

[Chalo]

5000km on my tzd2b in hilly norther Spain, eurovelo 3 (el Camino) and velosud in France from st jean de Luz to perpignon and it's still going. No mods or maintenance done, save straighter crank arms and a 38t chainring in a Rans recumbent, 120 kg rider.

Rider weight drops out of the reliability equation when it isn't riding on the bottom bracket. Recumbentists generally can't/don't pedal very hard (which is why they're so hungry for low gears), and neither do most e-bikers. So you may have found a decent application for an achy breaky mid drive, if you can tolerate its firmware quirks.