Bottom Shock Mount fills with water.

Taff

Member
Mar 7, 2019
20
14
UK
Seems some bikes have drain while others have foam tape from underside. Mine just fills with water on a wet ride which is game over for bearing.
Had to pack with poly foam to stop water pooling in there.

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Mikerb

E*POWAH Elite World Champion
May 16, 2019
6,567
5,058
Weymouth
motofoam would be a better bet and you could cut it so it fits a round the shock and on top of the lower shock bolt giving greater protection for the bearings.
 

Taff

Member
Mar 7, 2019
20
14
UK
You have no drain hole at all? Or is there a hole that's covered with tape? You can't remove the tape or cut a hole in it ?
Top picture- hole covered from inside frame with a foam tape insert. Shipped like that. If J remove water and debris drain straight onto motor and wiring. Just seeing how it compares to others out there.
 

Philly G

Well-known member
Jun 29, 2020
692
517
New Zealand
Top picture- hole covered from inside frame with a foam tape insert. Shipped like that. If J remove water and debris drain straight onto motor and wiring. Just seeing how it compares to others out there.
It's designed to drain through that hole - the motor is a sealed unit and the connectors (which are weather-proof in any case) are at the other end of the motor, so you won't cause any harm if you remove that foam tape and open the drain hole. I've had my Rail over 18 months now no issues whatsoever.
 

Peaky Rider

E*POWAH Master
Feb 9, 2019
847
538
Derbyshire Dales
The tape, which is present on my 2021 Rail 7, was clearly put there for a purpose. If it was not important surely it would be over, rather than under the hole. so it could be easily removed if so desired.

I prefer to fill the 'trough' with the black packing foam that comes with SRAM components and just clean it out after a ride. When I next take the shock off I might even fill the hole itself with sealant.

Reports suggest that the more water that finds its way onto a Bosch motor, the more you are asking for trouble, sealed unit or not.
 

Mikerb

E*POWAH Elite World Champion
May 16, 2019
6,567
5,058
Weymouth
clearly water needs to drain out so a hole at the bottom is needed. It is likely the hole is the size it is, because unguarded, the area at the bottom of the shock with get filled with trail debris and a decent sized hole would enable that to be cleaned out.
Motofoam is the best material to use over the top of that shock mounting area. Motofoam does not absorb water so allows it to pass through. Meanwhile it does stop trail debris. If it gets completely plastered in mud/leaves etc it can simply be washed and be good as new. A shape cut from a block of motofoam could fit around the base of the shock covering the bearing areas, with its "skirts" pushed down either side of the shock to the base of that recess.
 

Mikerb

E*POWAH Elite World Champion
May 16, 2019
6,567
5,058
Weymouth
Given how vulnerable to water and mud etc, the shock is, when mounted in that position, I would be looking at some form of gaiter to protect the shaft and that could also cover the shock bottom mounting area.
 

Philly G

Well-known member
Jun 29, 2020
692
517
New Zealand
Given how vulnerable to water and mud etc, the shock is, when mounted in that position, I would be looking at some form of gaiter to protect the shaft and that could also cover the shock bottom mounting area.
In theory...but in practice I don't think you'd ever get a gaiter with a perfect seal, so debris would still find its way in, and, trapped by the gaiter, risk scratching the shaft of the shock
 

Mikerb

E*POWAH Elite World Champion
May 16, 2019
6,567
5,058
Weymouth
...........they used to be de rigour for forks!!:D and are still used extensively in the automotive industry.....CV joints etc.
 

Peaky Rider

E*POWAH Master
Feb 9, 2019
847
538
Derbyshire Dales
clearly water needs to drain out so a hole at the bottom is needed. It is likely the hole is the size it is, because unguarded, the area at the bottom of the shock with get filled with trail debris and a decent sized hole would enable that to be cleaned out.

So why was my Rail delivered with that hole taped up and taped up in such a way that the tape is not easily removed?
Is it something that may have been left on at the end of the manufacturing process as an oversight?
Personally I'd rather change a couple of bearings periodically than add to the already high risk of motor failure due to water ingress
 

Philly G

Well-known member
Jun 29, 2020
692
517
New Zealand
So why was my Rail delivered with that hole taped up and taped up in such a way that the tape is not easily removed?
Is it something that may have been left on at the end of the manufacturing process as an oversight?
Personally I'd rather change a couple of bearings periodically than add to the already high risk of motor failure due to water ingress
The hole may have been taped for painting and was left on as an oversight? I wouldn't say there is a high risk of motor failure due to water ingress...I wouldn't go riding through rivers or in the sea ....but big puddles on trails, hosing down after muddy rides, no problem at all
 

Mikerb

E*POWAH Elite World Champion
May 16, 2019
6,567
5,058
Weymouth
If it was designed to be a sealed area why would they make a hole at the bottom in the first place?!!

As a bove the motor casing is a sealed unit. The plastic cover is not sealed but the electrical connections under there are protected and you can protect them further with some grease. Any water dripping from that hole would be insignificant compared to potential splasing with water off the trail every time you go through a puddle.
 

Taff

Member
Mar 7, 2019
20
14
UK
If it was designed to be a sealed area why would they make a hole at the bottom in the first place?!!

As a bove the motor casing is a sealed unit. The plastic cover is not sealed but the electrical connections under there are protected and you can protect them further with some grease. Any water dripping from that hole would be insignificant compared to potential splasing with water off the trail every time you go through a puddle.
Designed for drier climates? Taped for others?
Just seems like some are taped, others not, with no reasoning to it.
Thank you for all the responses.
 

Peaky Rider

E*POWAH Master
Feb 9, 2019
847
538
Derbyshire Dales
If it was designed to be a sealed area why would they make a hole at the bottom in the first place?!!

Because Trek thought it was a good idea until they got loads of knackered motors through water ingress, so they taped over the hole in such a way that the tape was not easy to remove :unsure:

There is also loads more drag on my 2021 motor than my mates 2020 motor, which feels and sounds as though it is coming from the bottom bracket axle. Possibly another lesson they (Trek & Bosch) have learned.
 

Stihldog

Handheld Power Tool
Subscriber
Jun 10, 2020
3,567
5,027
Coquitlam, BC
There is also loads more drag on my 2021 motor than my mates 2020 motor, which feels and sounds as though it is coming from the bottom bracket axle.
I have the 2020 gen4 motor on the Rail and it’s eerily quiet with almost no drag. It’s been completely submerged several times and I ride in the rain and mud. But the motor on the Powerfly 5 is a bit noisy. Can’t explain it. Maybe the motor on the Rail is broken-in differently. I asked the LBS and of course they said it doesn’t matter how wet the motor gets.
 

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