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

[honkinunit]

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]

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.

 

[motocatfish]

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-S...Performance-CX)

Good luck,

Catfish ...

 

[JackWare]

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.

 

[motocatfish]

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 ...