mid drive bosch motor exposed to elements

Brian Park

New Member
Hi again

Is this a problem or has it been for other users of the performance and active line motors? My Cube allroads is fitted with this motor and everyday it is being hit with mud, water and grit from the ground that is being thrown up by the front wheel. I'm sure Bosch has designed the casing so that it is weatherproof but on inspection there is a central seam that is not completely solid in terms of cover, i.e. there are a few gaps where the housing comes together. Is this going to be a problem long term? Should I cover the seam up with duck tape/gaffa tape or something similar?
I have heard of a few of the older bottom mounted motors filling up with gunk from the road but I would have hope this has been resolved now on the later motors.

Any thoughts/observations/personal experience?


Active Member
This sounds like a job for Dielectric Grease. Never used the stuff , but I've read alot about others that have, on scooter forums( Modern Vespa ) electrical connections exposed to moisture. Lots of pictures of it being used on that site .Hope this helps, Cubes look like mighty fine ebikes. Gotta take care of that Gem. Most users apply the grease improperly. It only goes on the rubber connector surface, where the plugs join , not the metal part . You tube has a good video on proper application. Sounds like Noalox anti - oxident is better for the metal connector part after reading an Amazon review. Good luck.
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Brian Park

New Member
Thanks for the tip, I do have reservations about smearing sticky grease all over the plastic motor housing. It may protect the electrics but it'll also pick up a lot of ground debris along the way! I just need someone to say (with conviction!) that Bosch are a company that know what they are doing and their motors are completely sealed from any and all external materials thrown at it by daily use on the road and trail.
Any takers?!!

Jack Tyler

Active Member
Brian, I'm a novice when it comes to ebike use but have had lots of experience on exposed electrical systems. I've seen many examples, in Court's review pics, where the location of a connection and/or the type of connection is questionable when it ultimately comes to hard use, the mix of chemicals on wet streets and the moisture inherent in trail riding debris. I don't see a reason to expect the Bosch mid-drive system to, long term, be immune from that concern you are raising. Here in Florida, where I'm about to leave, the benign weather isn't so much of a threat as the coastal blanket of salt-laden air but out in Montana, where the temperature spread can be 100F over a span of time, dissimilar expansion of the metal and plastic pieces does concern me. Add in riding in sand and snow like some of our fat bike owners do...one has to wonder.


Well-Known Member
Ive worked Nuclear Power plants for 30 years and know quite a bit about electrical and mechanical components exposed to the weather 24/7. General advice:

1. Keep the motor housing clean of debris by washing it off with a sponge and plain water regularly.. Allowing grit to dry and harden on the casing sets up anaerobic cells that will corrode though ANYTHING

2. Maintain the coating system.. Biggest cause of corrosion and moisture attack is the breakdown of the coating system...

3. Check the tightness of the bolted joints to keep the gasket sealing

Contact the Bosch Distributor (not the bike vendor or the Seller) and ask their recommendations.

Brian Park

New Member
All sage advice. I may need to speak to Bosch directly as you suggest as I'm more worried about the current openings in the casing and what they have already got harboured in them:eek:.
I generally always wipe the bike down after most dirty rides but that won't be enough to remove ingrained moisture and grit. I'd like to put my faith in a company like Bosch but those openings....


Well-Known Member
Well if your bike is under warranty I wouldn't go tearing into it ;) .. Take it to a shop and have them remove the housing in front of you so you can see what's gotten inside. Bosch can tell you if sealant is a good idea.

Ive had hub motors for 7 years and they are not sealed and get wet all the time.. Doesnt seem to hurt.


Well-Known Member

Dealing with the first concern that you raised in your other thread about battery connections etc I'll offer the following advice.

Starting at the handlebar end, water is prone to get between the HDMI (console) and the connecting housing bracket. It takes surprisingly little rain to enter between the two, and I would advise removal of the console between rides, the drying of the two components, and the application of dielectric lube. Most error codes can be traced back to either this element of the system or the battery connector. If you ever get error codes come up, check both first.


I also regularly remove the plastic cover from the mode setting switch and clean behind. With my off road use in all weather conditions, moisture and crud get behind. This doesn't affect the system in any way though.

Moving down to the battery. This is an area of concern, as water collects between the battery and the connecting block.

w2.JPG w3.JPG

With this area, as well as removing the battery after each ride and ensuring that the contacts are clean and dry on both the battery and the connection block, every few weeks or so, I also remove the plastic case that surrounds the block, as this is another trap for moisture and crud. Apply dielectric to the contact points.

w4.JPG Capture.JPG

At this point, I should also mention the lock that secures the battery. This is quite a problem if using the bike in adverse conditions, and soon becomes stiff in operation. I often remove and clean the outer plastic cover, and in respect of the lock, I use either graphite powder, or ceramic dry chain lube. Just a small dab of it, wiped on, then off the key, usually makes a massive difference.

Now the motor. My bike spends most of the time looking like this.

w6.JPG w8.JPG

What I will say is that you don't have anything to worry about in respect of the cases. Very little moisture actually ever enters the cases, and the connection blocks always remain moisture free.
I would suggest that you take a look to see if you have the plain alloy motor such as mine below.


If you do have plain cases, then I would strongly recommend using something such as ACF50 to coat the motor. They really do not like being even remotely damp, and corrosion quickly sets in. You might be lucky and have the new black cases, which presumably won't ever be an issue.

Now for one very important point. Go back to your dealer and ask if the outer bearing protection seal has been fitted to the sprocket side. This is a very important mod, and one that must be carried out if you ever intend to ride in adverse conditions. If it hasn't been fitted, request that they do so. edit.. Just spotted that you have the CX motor. This might well already have the mod. I'll find out for you.

A handy hint for you at bike washing time, is to remove both the console and battery, and then fit a latex glove to both mounts. As you will also see, I have some very large holes to the sprocket area of my motor cases. The cover was destroyed a very long time ago, but it does go to show, how even with these holes. very little in the way of water ever gets in.


Finally, please don't feel put off by what I have shown. My use of the e-mtb is very different to most, and whilst the above looks severe, the reality is that you have nothing to worry about. :)
The Bosch system is very good. Just get on and enjoy the bike. :)
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Brian Park

New Member
Wow! All I wanted in an answer. And more! My bike is generally used for commuting mainly on road with a small amount of hardpack trail. Nowhere near as much crud hits the motor as on your steed! The genius moment for me was the latex glove - my holy grail of weatherproofing whilst left locked outside in the rain.

Thanks again for all the info, if you could clarify whether the CSX motor has this bearing protection seal I would be deeply indebted good sir. Not sure what to look for with my newbie level of knowledge in this area...


Well-Known Member
Latex gloves prove to be a very handy cycle accessory, and I'm never without a few pairs. :)

I showed the crud as a way of hopefully reassuring you of just how effective that the cases actually are. I've not once seen water even remotely close to the connector blocks on the motor. Just keep an eye on the battery and console area though, as it takes very little for rain to creep in there. Oddly though, you can complete a road ride in a heavy shower and get nothing, but do the same ride the next day getting caught in a passing drizzle, and that will be the time that it gets in.

Just out of interest, did you get the bike from Chain reaction? I have friend that is currently intending to buy a Cube from them.

Brian Park

New Member
My box of latex gloves are already on order as will be my dielectric grease very soon. I take it a squirt of dry lube or gt85 wouldn't be an alternative ( not sure how this might affect the materials)?

I got my bike through Tredz using the 3 year interest free deal which was just too affordable to ignore!

Looking forward to finding some more hills to flatten this morning!

Thanks again for all the wisdom ;)


Thanks for that Brian, I'll let the friend know about Tredz. :)


I was just curious what kind of Haibike you had before you sold it? Did you replace the Haibike with the KTM?

I'm very inspired by your riding-in-any-weather style.



Well-Known Member
Thank you for the kind words Miraj.

You can find more exploits on the following. :)



The Haibike was this one. I'm afraid that I can't remember which model that it was though.


It made a brilliant road bike, and actually wasn't even that bad off road, especially considering that it wasn't really designed for it. The range was also very good, but I bought the bike without seeing it from Germany, and the frame size was just far too big for me. When they say large, they mean large! :)

It wasn't without it's issues though in respect of build quality. The welds were terrible and the white wheels had not been cleaned prior to being painted, so had traces of dust under the paint work. I also had issues with the rear wheel coming constantly loose. This was cured by the fitment of nuts from an very elderly 80's Raleigh bike. The rear hub also failed a few times, but that it is no way a reflection upon Haibike, and was just a faulty part, which could happen to any bike.

The Haibike was replaced by the KTM, and being truthful I'd never own another Haibike, and that is despite having been offered a very generously discounted price on one over here in the UK.
The full suspension bikes have well documented issues, and over here the consumable spare parts are almost mortgage money.

The KTM has a few design issues and aspects that should have been altered prior to production, but the overall build quality is superb. The bike is actually undergoing a full nut and bolt rebuild at the moment, and I'm half thinking of selling it in order to buy a hard tail Bosch powered KTM instead. The conditions here are pretty wet for eight months of the year, and the rear suspension bushes don't last overly long. This is not a design issue, and any full suspension bike would suffer equally from it. Sadly my location has talcum powder fine sand, which acts as a grinding compound.

I've really grown to love the Bosch motor, although I would still prefer that they hadn't changed to the small sprocket system. It's one of my pet hates about it. Nyon is another pet hate, and it really doesn't belong on an e-mtb. I have switched to Intuvia, but in the not too distant future, Bosch will be launching a dedicated and very small console, perfect for e-mtb use.
If you recall I also got a raw deal on here over the outer bearing failure that I suffered. I said at the time that it was a design issue, and there is now a modified seal available that should prevent this issue from ever happening again. So far it is working well. :) From my perspective KTM and Bosch have been very supportive, and I wouldn't hesitate in recommending either product. :)
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Well-Known Member
They fit the Active Line, Performance Line, and CX range. 2014/2015/2016 and it goes some way to solve the outer bearing issue that both myself and Lumos, were wrongly slated for. (sound familiar?)
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Active Member
Sorry for long to time reply..thanks!

I'm still enjoying the bike with Active line...but it is babied compared to your riding!