# US source for chainring for Bosch with 5mm offset for Plus/Boost



## honkinunit (Aug 6, 2004)

I have a Haibike with 27.5x3.0" tires and a Bosch Performance CX motor. To prevent the chain from hitting the tire when it is on the largest cog, Haibike made a custom chainring that spaces the front chainring out 5 mm or so, and has an integrated chainguard/chainguide. It works great, except that the chainring is an 18T and I need one that is smaller. I checked with a Haibike dealer and they want $140 for a 15T version. For one chainring. Nope.

I see that Trek is using Bosch motors with plus sized tires and they are using Miranda chainrings, at least it looks that way from the chainguard. I found the Miranda website and they don't appear to distribute to the US.

Does anyone know how to get a Miranda chainring? Will I have to go through Trek or is there another source?

https://mirandabikeparts.com/en/products/ebike-parts/sprocket-with-e-chainguard-nut/


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## JackWare (Aug 8, 2016)

Be careful when comparing the Miranda sprockets to your original Haibike piece as the inner toothed part that locks onto the CX drive flange can differ in thickness. If you take a close look at the difference images on the website or the image on my post below you'll see what I mean.


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## motocatfish (Mar 12, 2016)

I'd recommend you measure your chainring spacer thickness & have a local machine shop make you a blank spacer. Then you could order the cheap Bosch oem chainrings & bash ring from these folks. Ships to USA & takes paypal.
(https://www.e-bikeshop.co.uk/eBike-Spare-Parts/Bosch-eBike-Spares/Bosch-Performance-CX)

Good luck,

Catfish ...


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## JackWare (Aug 8, 2016)

It's not that simple as the driveshaft on the Bosch motor is a standard length and the Miranda drive gear makes up the difference, and I presume the Haibike version uses the same design but with an integrated outer guard.


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## motocatfish (Mar 12, 2016)

JackWare said:


> It's not that simple as the driveshaft on the Bosch motor is a standard length and the Miranda drive gear makes up the difference, and I presume the Haibike version uses the same design but with an integrated outer guard.
> View attachment 1225054


YIKES! I had no idea some bikes require that kind of huge offset for the Bosch. And with no splines under chainring at all?!? Whoooa!

What I suggested works for the Trek Powerfly. Sorry no help here.

Catfish ...


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