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

honkinunit

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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/prod...hainguard-nut/
 

JackWare

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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.
 

JackWare

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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.
ebike chainrings.jpg
 
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motocatfish

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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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