Where to get bosch cx chainring ?

Russelliow

Pedelecer
Apr 14, 2017
95
15
33
iom
So my original £40 boost sprocket arrived and is now fitted. However whilst awaiting delivery i got impatient and ordered one from here
https://r2-bike.com/BBB-chainring-E-Bike-Sprocket-for-Bosch-engines-BCR-70E
It costs half as much as the first one and comes with a new but. I thought it would just be a flat chainring with a spacer but it's all one piece like the original.
I haven't fitted it yet so no feed back on reliability.
 

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Michael Thain

Just Joined
Jun 17, 2018
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0
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how does the cheaper sprocket compare with the £40 one ? looking at your photo the teeth look shallow compared to the one on my bike(Trek Powerfly) ? £40 for a tiny sprocket, I can get a full chain and sprocket set for my motorbike for £25 more!
 

anotherkiwi

Esteemed Pedelecer
Jan 26, 2015
7,845
5,784
The European Union
9 speed cassette 11-36 = 13€
10 speed cassette 11-36 = 40€

Expensive extra cog! Same make (Sunrace)

SRAM will sell you an 11-36 10 speed cassette for 241€ and Shimano for 200€

All prices bike-discount.de, why pay more? :D
 

Russelliow

Pedelecer
Apr 14, 2017
95
15
33
iom
I have not used the cheaper one yet as I'm still on my first chain on the new cassette. 400 miles and still good. The cheaper one is offset exactly like the genuine one, it does not have a spacer. The only difference is it comes with a smaller nut.
 

Chris vicious

Finding my (electric) wheels
Feb 6, 2022
18
0
Hey guys and girls, im new to the site and have a similar problem as i purchased a KMC super narrow 20 tooth chainring for bosch performance line cx gen 2, it fits snug in the splines but can slide laterally as the lock ring does not press against it. I will send a few photos, any advice would be much appreciated
 

soundwave

Esteemed Pedelecer
May 23, 2015
12,789
5,248
was the sprocket you took off of set? ie spaced out from the motor so there was a gap?
 

Chris vicious

Finding my (electric) wheels
Feb 6, 2022
18
0
was the sprocket you took off of set? ie spaced out from the motor so there was a gap?
Thanks for you're quick reply, Yes it was a 16 tooth offset as the wheels are boost, i was thinking i might grind the original cog down and use it as a spacer.
 

Chris vicious

Finding my (electric) wheels
Feb 6, 2022
18
0
Also is there any app for this website or a way to get notifications when receiving a reply?
 

soundwave

Esteemed Pedelecer
May 23, 2015
12,789
5,248

this has a 2.5mm off set so if you can find a 20t one you can run a normal 18t behind it and then the lock ring you have will work.

you could also grind of the thread of one lock ring and the use that as a spacer with another lock ring.

the sprocket is off set for a reason so using one with no off set could wear the cassette down faster as the chain line wont be right.

 

Chris vicious

Finding my (electric) wheels
Feb 6, 2022
18
0

this has a 2.5mm off set so if you can find a 20t one you can run a normal 18t behind it and then the lock ring you have will work.

you could also grind of the thread of one lock ring and the use that as a spacer with another lock ring.

the sprocket is off set for a reason so using one with no off set could wear the cassette down faster as the chain line wont be right.


this has a 2.5mm off set so if you can find a 20t one you can run a normal 18t behind it and then the lock ring you have will work.

you could also grind of the thread of one lock ring and the use that as a spacer with another lock ring.

the sprocket is off set for a reason so using one with no off set could wear the cassette down faster as the chain line wont be right.

i dont have a spare lockring as the bike came with a miranda chainguard nut and the 20t i bought had no lockring with it, not that i expected one as it was just under 13 pounds.

I will try grinding the original cog first, if it does not work for whatever reason i will defo look at buying another cog from the site you mentioned above, thank you so much for taking the time to help me out, also is that your bike in video?
 

soundwave

Esteemed Pedelecer
May 23, 2015
12,789
5,248
yes it is my bike but when i had it from new it had a haibike sprocket fitted so the lock ring is 2 times the thickness of a normal one and i cant find one for sale anywhere atm.



might be a long shot but try peter and see if he has one or can get hold of one as fixes alot of bosch motors.


DSC_0160_02.JPG

as you can see if i used that blue lock ring it is to short but will work with 2 sprockets on the front like in the vid above.
 
Last edited:

soundwave

Esteemed Pedelecer
May 23, 2015
12,789
5,248
DSC_0148.JPG
18t normal and 20t with 2.5mm off set so i doubt grinding down 1 sprocket might not be enough.
 

soundwave

Esteemed Pedelecer
May 23, 2015
12,789
5,248

Chris vicious

Finding my (electric) wheels
Feb 6, 2022
18
0

it still does not look as thick as the one i have tho.
so many options to choose from and thanks for the photos they really help, i may invest in a decent digital caliper so when i grind the original sprocket i can make both exactly the same thickness as the original. i will also send a few photos soon so you can have a gander, also i think you have the same sprocket as me
 

soundwave

Esteemed Pedelecer
May 23, 2015
12,789
5,248
i have 3 options for front sprockets.

1 20t
dual 20t and 18t with the blue lock ring
18t xsync as use 12spd eagle

DSC_0110_02.JPG

you can not pull that chain off as locked on to it but only go up to 18t, haibike make a 20t one with xsync and its £100, and that one cost 20 quid :rolleyes:

20t is about as far as you can go any more and it out gears the motor with 25t it is pretty much useless even on the flat.
DSC_0673_01_01.JPG
 

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