battery mounting outside downtube

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raylo32   100 W

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battery mounting outside downtube

Post by raylo32 » Aug 12 2020 6:59am

Just wondering... I have an older Specialized Stumpjumper that doesn't have room in the triangle for my shark pack battery. But the frame does have a pair of rivnuts on the outside of the downtube. If I mount the battery there is would be "hanging" and be in tension rather than compression like in the inside of a triangle. Anyone tried this? Are the mounts strong enough to hold up without breaking? Or is it necessary (of just a good idea) to wrap such a battery install with straps to better secure it to the downtube?
Last edited by raylo32 on Aug 12 2020 7:03am, edited 1 time in total.

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MadRhino   100 GW

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Re: battery mounting outside downtube

Post by MadRhino » Aug 12 2020 7:02am

Never trust the screw inserts in a frame for anything heavy. You need to strap the battery to the tube.
Make it fool-proof, and I will make a better fool.
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Trek Session 10 mod. Variable geometry. 70mph
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raylo32   100 W

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Re: battery mounting outside downtube

Post by raylo32 » Aug 12 2020 7:10am

Good advice. I wouldn't ride this bike off road but still, the bumps on regular roads and bike paths can create momentary high forces. This one isn't built yet, just thinking about it still, because if/when I do it I'll need to get a new pedal MTB.
MadRhino wrote:
Aug 12 2020 7:02am
Never trust the screw inserts in a frame for anything heavy. You need to strap the battery to the tube.

MikeSSS   100 W

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Re: battery mounting outside downtube

Post by MikeSSS » Aug 12 2020 9:27pm

In a few days, after 400 miles on the bike, I'll post pics of my battery mounted on the left side of the front "triangle" area.

This works very well and gives a good center of gravity when stopped. When the rider is mounted, rider weight on the bike, even a rear rack mounted battery is OK.

Returnformer   10 W

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Re: battery mounting outside downtube

Post by Returnformer » Aug 12 2020 11:38pm

thats where i put my battery, on the underside of the downtube. i mounted it using the triple bob from grin (i wish they made a quadruple bob) which i screwed into the two mounts on the lower end of it and used a hose clamp to secure the top end. battery mount is attached to that. once i have the battery itself mounted, i used a velcro strap to secure the battery as well for reinforcement.

when mounting in this location, you have to check the front suspension, that the tire doesnt hit the battery when fully compressed. i had to limit mine to the lowest setting.
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raylo32   100 W

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Re: battery mounting outside downtube

Post by raylo32 » Aug 13 2020 7:24am

Hey, thanks for that info, the "triple Bob" looks like just the ticket. I also have some rivnuts so I could add more attach points.
Returnformer wrote:
Aug 12 2020 11:38pm
thats where i put my battery, on the underside of the downtube. i mounted it using the triple bob from grin (i wish they made a quadruple bob) which i screwed into the two mounts on the lower end of it and used a hose clamp to secure the top end. battery mount is attached to that. once i have the battery itself mounted, i used a velcro strap to secure the battery as well for reinforcement.

when mounting in this location, you have to check the front suspension, that the tire doesnt hit the battery when fully compressed. i had to limit mine to the lowest setting.

Returnformer   10 W

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Joined: Apr 12 2019 12:00am

Re: battery mounting outside downtube

Post by Returnformer » Aug 13 2020 4:18pm

raylo32 wrote:
Aug 13 2020 7:24am
Hey, thanks for that info, the "triple Bob" looks like just the ticket. I also have some rivnuts so I could add more attach points.
be careful adding holes, if theyre not perfectly round theyll create a stress point that can lead to the frame cracking.

the main reason i used the bob was to raisethe battery mount up (technically down) a bit to get part the cable mount/brackets which stuck out a bit past the underside of the downtube. but its also useful for the extra mounting point. i could have had another mounting point as well (hence why i think they should make a quadruple bob) asthe battery mount has 4 holes, so if i had thought about it i would have ordered a pack of the single bobs as well when i ordered the triple and a torque arm. but because of the shipping its too expensive now so im not gonna bother. but worth considering if you didnt order yet and have a 4th hole.

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