under down tube battery mount

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raylo32   100 W

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under down tube battery mount

Post by raylo32 » Aug 27 2019 6:54am

Thinking about electrifying my old Specialized Stumpjumper FSR that probably doesn't have room in the triangle for my 52V super shark pack. I see Luna sells a bike with a similar battery mounted beneath the down tube. Does anyone know if and where such an adapter can be sourced? See the product below for a photo of this setup. I guess I could probably cobble something together with a stainless band or clamp or somesuch but it would be nice to have a more finished solution.

https://lunacycle.com/luna-lone-wolf-fu ... -stance-2/

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motomech   1 GW

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Re: under down tube battery mount

Post by motomech » Aug 27 2019 7:56am

You don't need an adaptor. Both my mountain bikes came w/ water bottle mounting lugs (threaded bosses) on the underside of the frt. downtube. If they are not there, any bike shop can install them for a nominal fee.
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Ford Prefect   1 W

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Re: under down tube battery mount

Post by Ford Prefect » Aug 27 2019 8:50am

I think we had this some time back :es:

There were two main concerns:
- ground clearance and clearance of the front wheel.
- water. These cases are designed the other way around. So using them upside down could (not "will"!!!) make them flooding in rain or other fluids.

I will try to find the infos tonight.
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raylo32   100 W

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Re: under down tube battery mount

Post by raylo32 » Aug 27 2019 8:54am

Well, this is a big d'oh on my part. My bike does indeed already have water bottle bosses under the down tube. Looks like I have plenty of clearance to the front wheel and not really worried about water. I don't ride in the rain and won't be single tracking this rig through streams. There is still a chance the battery may fit in the triangle... actually it does fit. But not sure there is then room to slide it on and off its mount.

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E-HP   10 kW

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Re: under down tube battery mount

Post by E-HP » Aug 27 2019 8:58am

raylo32 wrote:
Aug 27 2019 6:54am
Thinking about electrifying my old Specialized Stumpjumper FSR that probably doesn't have room in the triangle for my 52V super shark pack. I see Luna sells a bike with a similar battery mounted beneath the down tube. Does anyone know if and where such an adapter can be sourced? See the product below for a photo of this setup. I guess I could probably cobble something together with a stainless band or clamp or somesuch but it would be nice to have a more finished solution.

https://lunacycle.com/luna-lone-wolf-fu ... -stance-2/
What year is your FSR? The frame has changed a lot through the years, and some look like they could present a clearance problem when the fork is fully compressed.

Zooming in on the pic of the Luna bike and it looks almost like that bracket is zip tied into place.

raylo32   100 W

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Re: under down tube battery mount

Post by raylo32 » Aug 27 2019 9:13am

It's a 2003 but upgraded with XT disks and tubeless. I will probably get a new MTB for hitting the trails so this FSR rig would be for general purpose street and gravel ebike duty. I have looked at it briefly and seems to be OK for clearance, but I will test before going forward. I have a spare empty super shark battery case I can mount up and then compress the fork to check.
E-HP wrote:
Aug 27 2019 8:58am
raylo32 wrote:
Aug 27 2019 6:54am
Thinking about electrifying my old Specialized Stumpjumper FSR that probably doesn't have room in the triangle for my 52V super shark pack. I see Luna sells a bike with a similar battery mounted beneath the down tube. Does anyone know if and where such an adapter can be sourced? See the product below for a photo of this setup. I guess I could probably cobble something together with a stainless band or clamp or somesuch but it would be nice to have a more finished solution.

https://lunacycle.com/luna-lone-wolf-fu ... -stance-2/
What year is your FSR? The frame has changed a lot through the years, and some look like they could present a clearance problem when the fork is fully compressed.

Zooming in on the pic of the Luna bike and it looks almost like that bracket is zip tied into place.

raylo32   100 W

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Re: under down tube battery mount

Post by raylo32 » Aug 27 2019 9:49am

Just test fitted the super shark case and there is plenty of clearance. This pic with fork uncompressed but there is still plenty of room when I compress it fully. I also test fitted it inside the triangle and it doesn't work. It *might* fit if I ground down the ridges on the nose of the battery case. But I'd rather not.
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E-HP   10 kW

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Re: under down tube battery mount

Post by E-HP » Aug 27 2019 10:20am

raylo32 wrote:Just test fitted the super shark case and there is plenty of clearance. This pic with fork uncompressed but there is still plenty of room when I compress it fully. I also test fitted it inside the triangle and it doesn't work. It *might* fit if I ground down the ridges on the nose of the battery case. But I'd rather not.
Looks good. Did you try the battery in the opposite direction in the triangle. The profile of the battery looks similar to the angle of the downtube and other frame member (not really a seat tube on that frame).


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raylo32   100 W

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Re: under down tube battery mount

Post by raylo32 » Aug 27 2019 10:24am

No I didn't. Seems like of you mounted the battery that way there'd be a lot of stress on the locking pin whereas the plastic frame takes it all when mounted nose up.
E-HP wrote:
Aug 27 2019 10:20am
Looks good. Did you try the battery in the opposite direction in the triangle. The profile of the battery looks similar to the angle of the downtube and other frame member (not really a seat tube on that frame).


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RunForTheHills   100 W

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Re: under down tube battery mount

Post by RunForTheHills » Aug 27 2019 11:44am

raylo32 wrote:
Aug 27 2019 10:24am
No I didn't. Seems like of you mounted the battery that way there'd be a lot of stress on the locking pin whereas the plastic frame takes it all when mounted nose up.
I don't have personal experience with one, but the Luna Wolfpack uses a magnetic mount and doesn't clip in like a shark enclosure does. It is also fully potted, which is why they can mount it under the downtube without worrying about water getting inside.

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