LMT’D Downtube/BB Water/Grime Ingress

[Claypool]

The cable exit at the bottom of the LMT’D downtube is stressing me out. It’s almost like it was designed to cause water to drain into the torque sensing bottom bracket.

After my first wet ride I was alarmed to see the hole completely filled with grime and water. Upon removing the lower battery mount, I could see water and grime just sitting on top of the bottom bracket with apparently nowhere to go but into the bb.

I wound up drying it out and filling the space with silicone caulk. Sometimes I tape the opening completely from the outside. I then use a plastic MTB fender to cover the area, although it’s not taped to the downtube and it’s open at the bottom. Can anyone allay my worries or offer better methods? I used to worry about water getting into the bottom of my 700 but that’s a non-issue compared to this janky engineering.

Thanks in advance!

 

[Rexlion]

Wow, I just checked my LMT'D and it does look rather grubby down there! Not stuffed full of dirt like yours, but some mud has splattered the area. I guess I will clean it up and then cover that area with some Gorilla brand duct tape to keep the splashes away. Thanks for causing me to notice it!

 

[Claypool]

Wow, I just checked my LMT'D and it does look rather grubby down there! Not stuffed full of dirt like yours, but some mud has splattered the area. I guess I will clean it up and then cover that area with some Gorilla brand duct tape to keep the splashes away. Thanks for causing me to notice it!

And if you’re like me you’ll never forget it lol. My silicone job is sloppy and of doubtful effectiveness but I had to do something. I even keep a couple paper towels in there too. The sharp edges in the frame were filed down, per a recommendation from either here or the Facebook group.

I think my little fender deal over the bottom opening is my best hope besides trying to tape it closed. The bottom can potentially be sealed up but then there’s ingress where the cables enter the top of the downtube! It’s the reason I took the black cable wrap off—it’s just a place for water to unknowingly accumulate and trickle in. I see numerous drain holes in the frame and I swear, if they drain to the bottom bracket I’m going to have an aneurism.

 

[PCeBiker]

I had a similar problem with my ebike.

Water and dirt can get past the bottom battery bracket where it's fed directly into the bottom bracket via the conveniently located drain hole.
(Fricken Stupid design.)

I drilled a tiny weep hole in the bottom of the bottom bracket to let any water drip out.

It's not just liquid water that can drain into the bottom bracket, water can condense inside any of the frame tubes then drain to the lowest point, which is the bottom bracket.

My frame has no drain holes anywhere on the frame so any condensation that forms or water that get in will drain into the bottom bracket.

I spray lube up through the drain hole to make sure it doesn't dry out then any water will bead up and find its way to the weep hole.

 

[Claypool]

Wow, thanks for your input! I just don’t understand these designs. Your fix has me contemplating this move but I’m going to let it simmer for a bit (like the liquid in my bottom bracket). My BB has a torque sensor built in so it’s like $150 to replace and it’s difficult to remove. Thanks again for your helpful response!

 

[PCeBiker]

I figure that water collecting in the bottom bracket is inevitable, even if it's just from condensation.
Every bike I had as a kid (as far as I can remember) had a drain hole in the bottom bracket.

If water collects in the bottom bracket, the hardened steel ball bearings will rust.
Even sealed bearings will end up with water in them if they are submerged in water.

 

[Claypool]

I figure that water collecting in the bottom bracket is inevitable, even if it's just from condensation.
Every bike I had as a kid (as far as I can remember) had a drain hole in the bottom bracket.

If water collects in the bottom bracket, the hardened steel ball bearings will rust.
Even sealed bearings will end up with water in them if they are submerged in water.

Boy oh boy do I hear ya! Here’s the bottom bracket from my Ride1Up 700 after 3 months and 500 miles. It looks like I operated the bike in the Mariana Trench but that was not the case lol! Water easily entered through the gap left by the cadence sensor, which now just so happens to ship with a rubber gasket to fill the empty space.

 

[PCeBiker]

I guess the gasket would help but water or condensation can always find its way into the bottom bracket, then the seal may actually hold the water inside.

The bearings are always heating up and cooling off and if the water level rises up to the seal on the bearing, the bearing can suck water past the seal when it cools.

Same thing happened to the front wheel bearings on my car.

 

[Claypool]

Ah, thanks for that tidbit. I’ve heard similar about hub motors.

 

[PCeBiker]

Ah, thanks for that tidbit. I’ve heard similar about hub motors.

Oh s*it.
I didn't think about my hub motor.

Now I'm going to have to take it apart and look.
Maybe I'll drill a hole in it?

 

[Claypool]

Have I got news for you! Bafang motor after a few months and a few hundred miles. I’ve heard that the pressure differential creates a vacuum and can suck water through the axle opening. I cleaned the s*it out of it with numerous earth-destroying chemicals and a wire brush, then packed it to the gills with grease and rode it harder than I would any other motor. It got rid of all the remaining junk and then I cleaned it once more. It still whines like crazy on deceleration.

I’ve seen Grin make mention of drilling holes in motor casings but that’s out of my realm!

 

[PCeBiker]

Ahhh!!...

Well, luckily my e-bike hasn't seen any rain and I've only ever washed it once.

I guess water can find its way inside even if it has never been submerged up to the axle?

My ebike does say to not submerge it up to the axle.

 

[Claypool]

Ahhh!!...

Well, luckily my e-bike hasn't seen any rain and I've only ever washed it once.

I guess water can find its way inside even if it has never been submerged up to the axle?

Correct. So now I’m absolutely nuts with keeping the motor cable dry where it exits the axle. I also lean the bike against something on its right side if I feel the slightest dampness, of course after I dry the axle, protective spring and rubber sheathing. Perhaps the leaning messes with evaporation but whatever lol. I’ll just open ‘er up more than is probably necessary. Stripping screws is one of my favorite hobbies.

 

[PCeBiker]

Yeah, I didn't think about the motor cable. I was thinking bearings.
What about caking the cable/axle with silicone?
You can use black RTV silicone so it doesn't look so trashy.

PS... My motor cable comes out the left side on my Das-Kit motor, so I'd have to lean my bike to the left.

 

[Claypool]

I don’t know about the silicone deal. It’s tempting but I worry about it interfering with the normal cooling/heating cycle.

And you’ve got a built-in solution for the lean!

 

[PCeBiker]

I don’t know about the silicone deal. It’s tempting but I worry about it interfering with the normal cooling/heating cycle.

Yeah, I suppose it could work against you by sealing water in instead of keeping it out, especially with the suction created by the quick cooling of getting wet when it's hot.

And you’ve got a built-in solution for the lean!

I installed a center stand.
I'm still going to have to lean my bike.

 

[Rexlion]

Hey, if it lasted forever they could never sell you a new one.