Bosch Gen 4 - How to change the chainring?

[GrahamPaul]

Can anyone point me towards a video/instruction manual for changing the chainring on the new CX Gen 4?

 

[Aleksiron]

Hey!

Im having same intentions.

Im guessing just to take crank off (allen key) and then the lockring which requires specific tool. Ive tried to search right tool but those are little under a bush. found somewhere bosch's original key that cost like 60e.. trying to find cheaper one.

In my Cube Stereo Hybrid 140 i have 34t chainring.
Going to try 38t ring.

 

[Jamy]

Hey!

Im having same intentions.

Im guessing just to take crank off (allen key) and then the lockring which requires specific tool. Ive tried to search right tool but those are little under a bush. found somewhere bosch's original key that cost like 60e.. trying to find cheaper one.

In my Cube Stereo Hybrid 140 i have 34t chainring.
Going to try 38t ring.

one of the main reasons I bought an hardtail instead of full sus. As the bike was gonna mainly be used for commuting I thought a 34t chainring was too small.

 

[Zimmerframe]

I think something like this would do it .. I have one for the Kenevo and think it's the same one on the Bosch ..

I believe, due to it's "rampart" shape .. it's called a castle nut tool.

www.amazon.fr/dp/B07NR26FY1/ref=pe_3044141_189395771_TE_dp_2

 

[Aleksiron]

I think something like this would do it .. I have one for the Kenevo and think it's the same one on the Bosch ..

I believe, due to it's "rampart" shape .. it's called a castle nut tool.

www.amazon.fr/dp/B07NR26FY1/ref=pe_3044141_189395771_TE_dp_2

Yep that thing have many names. Spider tool, lockring tool and castle nut tool. Different Bosch motors have different diameter in the nut. That one fits gen 3 motors. not sure about gen 4, maybe!

 

[GrahamPaul]

I think something like this would do it .. I have one for the Kenevo and think it's the same one on the Bosch ..

I believe, due to it's "rampart" shape .. it's called a castle nut tool.

www.amazon.fr/dp/B07NR26FY1/ref=pe_3044141_189395771_TE_dp_2

Yep that thing have many names. Spider tool, lockring tool and castle nut tool. Different Bosch motors have different diameter in the nut. That one fits gen 3 motors. not sure about gen 4, maybe!

Thank you both. I'll measure up the locking ring to get the right size tool. At least now I know what I'm looking for

Does the centre allen key bolt have a standard right-hand thread? (Is the one on the other side a left-hand thread?)

Oddly, at 1000km I found no visible chain stretch when I compared the Shimano 12sp chain to a new one. I really couldn't see any difference in length hanging them side by side. However, the chain ring is, I think, alloy and I am cutting my fingers on those teeth. Just looking at the shapes, I think they are kinda worn...

 

[GrahamPaul]

One other quick question. I found the Bosch Lock Ring Tool on a local website and it seems to indicate the lock ring has a left-hand thread if I read the "Open<->Close" description correctly. Do I read this correctly?

(I see that this is a Gen 2 tool, but I'll do a measure up to see if it is the same. And I'll drop a note to Bosch as well. Their helpline is very errr... helpful).

 

[Doomanic]

it seems to indicate the lock ring has a left-hand thread if I read the "Open<->Close" description correctly. Do I read this correctly?

Yes.

I see that this is a Gen 2 tool, but I'll do a measure up to see if it is the same.

It's not.

Does the centre allen key bolt have a standard right-hand thread?

The Gen 2 did, I haven't tried a Gen 4 yet.

 

[Aleksiron]

Bosch Active / Performance CX Gen 4 2020+ Spider Tool

Im going to order that.

 

[GrahamPaul]

Bosch Active / Performance CX Gen 4 2020+ Spider Tool

Im going to order that.

Thanks! So it is a different size to anything previous.

I see that a crank puller is needed as well. Any idea whether this is the same size as the Shimano one (which I already have)? Or yet another size?

 

[GrahamPaul]

I've heard back from Bosch, who have confirmed the following:

The tools for generation 2 and 4 are different.​

​

You can find all of the tools on Magura's website (just for dealers).​

​

In generation 4th Drive units is left hand thread.​

​

You can check for those tools on:​

​

www.magura-b2b.com​

So... the tools are different and the official ones are only available to dealers

 

[Like a Boss]

Go to Park Tools USA website and see the following:
BBT-18
-Shimano® Octalink® right side bottom bracket cup with external notches
-Bontrager® ISIS Drive™ bottom bracket cups
-Front chainring lockring for Bosch® Gen 3 and Gen 4 e-bike systems

I haven't used it myself, but Calvin at Park sent me that info.

 

[Like a Boss]

Go to Park Tools USA website and see the following:
BBT-18
-Shimano® Octalink® right side bottom bracket cup with external notches
-Bontrager® ISIS Drive™ bottom bracket cups
-Front chainring lockring for Bosch® Gen 3 and Gen 4 e-bike systems

I haven't used it myself, but Calvin at Park sent me that info.

Notice, however, that this Park BBT-18 seems to re

Go to Park Tools USA website and see the following:
BBT-18
-Shimano® Octalink® right side bottom bracket cup with external notches
-Bontrager® ISIS Drive™ bottom bracket cups
-Front chainring lockring for Bosch® Gen 3 and Gen 4 e-bike systems

I haven't used it myself, but Calvin at Park sent me that info.

I ended up buying the Unior 8 Tooth Cartridge Bottom Bracket Tool - 1671.2/4.
I emailed Unior and they say this one fits. The Union tool uses a standard 1/2" drive to attach to a breaker bar or torque wrench. The Park tool uses an eight point configuration which means you need a 12 point socket, or a 36mm crow's foot to torque it to spec.
So I'll see if the Union version works for me when it gets here.

 

[GrahamPaul]

Notice, however, that this Park BBT-18 seems to re

I ended up buying the Unior 8 Tooth Cartridge Bottom Bracket Tool - 1671.2/4.
I emailed Unior and they say this one fits. The Union tool uses a standard 1/2" drive to attach to a breaker bar or torque wrench. The Park tool uses an eight point configuration which means you need a 12 point socket, or a 36mm crow's foot to torque it to spec.
So I'll see if the Union version works for me when it gets here.

Thanks.

I already had misgivings about the Park Tool kit because of the need for a crows foot spanner.

I'll follow up on the Unior once our lockdown has ended and I can actually get to my garage again.

 

[Zimmerframe]

Thanks.

I already had misgivings about the Park Tool kit because of the need for a crows foot spanner.

I'll follow up on the Unior once our lockdown has ended and I can actually get to my garage again.

Does it have a tooth extractor ?

 

[GrahamPaul]

Does it have a tooth extractor ?

That, sir, is just plain evil and wicked of you! ?

When I've given the tooth fairy a good spanking, I send her your way!

 

[Like a Boss]

Notice, however, that this Park BBT-18 seems to re

I ended up buying the Unior 8 Tooth Cartridge Bottom Bracket Tool - 1671.2/4.
I emailed Unior and they say this one fits. The Union tool uses a standard 1/2" drive to attach to a breaker bar or torque wrench. The Park tool uses an eight point configuration which means you need a 12 point socket, or a 36mm crow's foot to torque it to spec.
So I'll see if the Union version works for me when it gets here.

The Union tool works perfectly. But I am frustrated with the Bosch aluminum locking ring. My Rail had a thin o ring between the chainring and the locking ring. The ring has a torque spec printed (25-30 nm). My torque wrench only reads a torque value clockwise, and this ring is tightened anti-clockwise. When tightening the chainring locking ring, the o ring bunches up and doesn't lay flat, even with a little grease. Also, the locking seems to shed aluminum bits when coming on and off. The chainring sort of wobbles on the Bosch spindle before it is tightened down. I am not impressed with how it works. The steel e13 chainring presents a 52mm chainline. I wanted more clearance between the chain stay and the chainring so I bought the e13 alloy chainring which specifies that it makes a 53mm chainline. However the chain guide rubs with the alloy chainring. The spacers for the chainline are plastic 4 or 4.5 mm spacers, but that isn't enough for a greater chainline. It's all sort of a hassle.

 

[Like a Boss]

The Union tool works perfectly. But I am frustrated with the Bosch aluminum locking ring. My Rail had a thin o ring between the chainring and the locking ring. The ring has a torque spec printed (25-20 nm). My torque wrench only reads a torque value clockwise, and this ring is tightened anti-clockwise. When tightening the chainring locking ring, the o ring bunches up and doesn't lay flat, even with a little grease. Also, the locking seems to shed aluminum bits when coming on and off. The chainring sort of wobbles on the Bosch spindle before it is tightened down. I am not impressed with how it works. The steel e13 chainring presents a 52mm chainline. I wanted more clearance between the chain stay and the chainring so I bought the e13 alloy chainring which specifies that it makes a 53mm chainline. However the chain guide rubs with the alloy chainring. The spacers for the chainline are plastic 4 or 4.5 mm spacers, but that isn't enough for a greater chainline. It's all sort of a hassle.

I haven't found a Bosch manual that has instructions for installing the chainring. Apparently it isn't a user level maintenance action. The Bosch Performance Line CX user's manual says that all these actions must be performed at the dealer.

 

[GrahamPaul]

I haven't found a Bosch manual that has instructions for installing the chainring. Apparently it isn't a user level maintenance action. The Bosch Performance Line CX user's manual says that all these actions must be performed at the dealer.

Oh! That is not good.

Have you tried getting the information directly from Bosch via their helpline?

 

[Aleksiron]

I ended up to order new 36t chainring and gave it to my local bike shop do change it when i took my cube to first maintenance, cost 25€.

 

[Aleksiron]

I ended up to order new 36t chainring and gave it to my local bike shop to change it when i took my cube to first maintenance, cost 25€.

 

[GrahamPaul]

I ended up to order new 36t chainring and gave it to my local bike shop do change it when i took my cube to first maintenance, cost 25€.

Thanks. I'm forewarned.

 

[Like a Boss]

The Union tool works perfectly. But I am frustrated with the Bosch aluminum locking ring. My Rail had a thin o ring between the chainring and the locking ring. The ring has a torque spec printed (25-20 nm). My torque wrench only reads a torque value clockwise, and this ring is tightened anti-clockwise. When tightening the chainring locking ring, the o ring bunches up and doesn't lay flat, even with a little grease. Also, the locking seems to shed aluminum bits when coming on and off. The chainring sort of wobbles on the Bosch spindle before it is tightened down. I am not impressed with how it works. The steel e13 chainring presents a 52mm chainline. I wanted more clearance between the chain stay and the chainring so I bought the e13 alloy chainring which specifies that it makes a 53mm chainline. However the chain guide rubs with the alloy chainring. The spacers for the chainline are plastic 4 or 4.5 mm spacers, but that isn't enough for a greater chainline. It's all sort of a hassle.

I haven't found a Bosch manual that has instructions for installing the chainring. Apparently it isn't a user level maintenance action. The Bosch Performance Line CX user's manual says that all these actions must be performed at the dealer.

Oh! That is not good.

Have you tried getting the information directly from Bosch via their helpline?

I have not done that. Are they responsive?

 

[Like a Boss]

I wrote a message on the Bosch contact page at bosch-ebike.com. I had a "thanks for the message" confirmation. They also list a telephone number for the USA at Tel: 1-833-BOSCH-EB (267-2432). I may call that later.

 

[GrahamPaul]

I haven't found a Bosch manual that has instructions for installing the chainring. Apparently it isn't a user level maintenance action. The Bosch Performance Line CX user's manual says that all these actions must be performed at the dealer.
I have not done that. Are they responsive?

They certainly are here in Europe. You should get an answer within 24 hours.

If you don't like the answer then try the phone line. I'm never keen on those 'cos I reckon it's students reading a script off a screen. I've not tried the phone line because they've always answered my question.

 

[Like a Boss]

I never did get an email reply. I called the USA support number and talked to a tech who seemed to be working from home. He said the o-ring is required. I did get a part number for the o-ring, but no other guidance except to go to a dealer. 1270016119 is the part number. I can't tighten the lockring to 25-30 Nm without the o-ring squirming out of place. Very frustrating, and I don't think it is a solid design. Why not just have a steel lockring, a higher torque value, and perhaps use a blue locktite? The alloy lockring generates alloy bits every time it comes on and off. This does not give me confidence that the lockring will stay tight, as many users have already experienced. There is no reason for this to occur during a ride on the trail.

 

[Like a Boss]

FYI the lockring must be torqued ccw (counter clockwise). Not all torque wrenches do this as I discovered. The Park TW-6.2, however, will read torque in CW or CCW direction. The Unior 8 Tooth Cartridge Bottom Bracket Tool - 1671.2/4 is 1/2" drive, so a 3/8 to 1/2" adapter is necessary when using the Park torque wrench. If anyone knows of another torque wrench that will read torque in both directions, please post. The Park is three times the cost of many torque wrenches that appear on amazon or eBay, for example.

 

[Aleksiron]

lockring needs to be tighten properly. Mine just came loose today. chainring was changed 3weeks ago. gotta get angry call to local workshop on monday that they need to re tighten lockring and maybe use loctite or something. Need to get tools to myself so there is no need to go always to workshop..

 

[GrahamPaul]

Well that's annoying... The crank puller for the Bosch motor is NOT a Park Tool CCP-22.

Anyone know what the correct crank puller reference number is?

(Should have checked... I now have two CCP-22 tools ?‍. I shouldn't have trusted a dumb sales website.)

 

[Like a Boss]

The Bosch Gen 4 spindle is ISIS/Octalink type.