DH Comp Rotomax Mid drive

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Feist92   1 mW

1 mW
Posts: 19
Joined: Sep 12 2017 5:27pm

Re: DH Comp Rotomax Mid drive

Post by Feist92 » Jul 13 2019 9:04pm

Ive made up a sprocket adapter and fitted it to the bike, I was in a bit of a rush so the machining is a bit rough in places but it turned out ok. Ive just mocked it up for now.
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Im starting to look into chucking the battery in a back pack as I cant fit it where I wanted to under the down tube. Im fairly sure the front wheel will hit it under full compression

I decided to take the shock off the frame so I could check the chain growth with my intended routing but ran into a significant problem. Almost every part of the suspension linkage has been munted by the guy I bought it off. Its been bodged together so I had no idea how bad it was till now. Safe to say its really killed my motivation
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DanGT86   10 kW

10 kW
Posts: 648
Joined: Sep 06 2012 9:18pm
Location: Saint Louis MO

Re: DH Comp Rotomax Mid drive

Post by DanGT86 » Jul 13 2019 9:53pm

Sorry to hear about the suspension. I'm always amazed they hold up as long as they do. Everything on bikes seems impossibly thin. Looks like you have the skills to repair or remake the suspension parts if you have to. You could probably bore and sleeve some of those parts and they'd be stronger than ever. It does suck having to go back and make stuff you thought was fine. Maybe take a break from it and go ride something else to get your motivation back.

The work looks awesome so far. Hurried rough machining looks cooler than smooth machining to most people anyway.

cheapcookie   100 W

100 W
Posts: 148
Joined: Aug 02 2014 10:34pm
Location: Earth

Re: DH Comp Rotomax Mid drive

Post by cheapcookie » Jul 14 2019 1:37am

Son of a gun! looks like a mean machine!

Is the motor output freewheeled ? or can take advantage of regen braking ?

xiteamxi   100 mW

100 mW
Posts: 43
Joined: Oct 29 2015 5:55pm

Re: DH Comp Rotomax Mid drive

Post by xiteamxi » Jul 14 2019 7:29pm

Old thread.. but looks like no freewheel so regen possible, would be nice to see if this project was ever finished some nice machine work going on there... with a good battery no doubt this thing would be an animal.

flat tire   1 MW

1 MW
Posts: 1592
Joined: Feb 26 2014 12:20am

Re: DH Comp Rotomax Mid drive

Post by flat tire » Jul 14 2019 7:43pm

Bike looks nice, battery backpacks suck hard and top tube battery mounts are an easy solution on any bike.

Feist92   1 mW

1 mW
Posts: 19
Joined: Sep 12 2017 5:27pm

Re: DH Comp Rotomax Mid drive

Post by Feist92 » Jul 21 2019 7:15pm

Ive done what should be enough of a fix for the mean time, it might even be stronger than before but it is a bit ugly.
The shock should be ok for some testing but it really is a bit naff
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j bjork   100 W

100 W
Posts: 255
Joined: Aug 31 2018 3:01pm
Location: Linköping, Sweden

Re: DH Comp Rotomax Mid drive

Post by j bjork » Jul 22 2019 6:25am

Nice build, keep it up :thumb:

Feist92   1 mW

1 mW
Posts: 19
Joined: Sep 12 2017 5:27pm

Re: DH Comp Rotomax Mid drive

Post by Feist92 » Aug 17 2019 11:45pm

So I just broke some of the wires in the motor trying to add internal hall sensors.
I guess I'm rewinding the stupid thing

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neptronix   100 GW

100 GW
Posts: 13944
Joined: Jun 15 2010 5:56pm
Location: California refugee living in Utah, USA
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Re: DH Comp Rotomax Mid drive

Post by neptronix » Aug 17 2019 11:53pm

That sucks to hear :lowbatt:
Efficiency is everything :bolt:

My first major build: 1.6kW 8T MAC motor on a Trek 4500.
The new all-arounder: Leafmotor 1500w @ 4kW on a Turner O2 full suspension.
The monster scooter: 20" eZee on a Cannondale Semi Recumbent.
Whipper-snapper: ? on a lightweight BikeE Semi Recumbent

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DanGT86   10 kW

10 kW
Posts: 648
Joined: Sep 06 2012 9:18pm
Location: Saint Louis MO

Re: DH Comp Rotomax Mid drive

Post by DanGT86 » Aug 18 2019 1:18pm

That does suck but at least you'll know its done well. My 80100 outrunner had strands of wire that were loose and just hanging out if the bunch. Some were long enough to scrape on the magnets or get wedged in the air gap. Quality control isnt exactly what these motors are known for.

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