Mounting Hairon/Shark type packs on a Yuba Mundo's downtube

[Skizz]

Hi all,

I'd be grateful for thoughts on non-destructive mounting of battery packs on the Yuba Mundo downtube.

We've a brand new Mundo V5 frameset on which I need to mount a 17.5Ah Hairon (shark style) pack. It's a heavy pack that needs good support (3-4 point) but being a new frame I can't just insert additional rivnuts like I did with our Ute without invalidating the warranty.

The factory bottle-bosses line up roughly with additional holes I drilled in the alloy portion of the battery's mounting plate but this would leave the top half of the pack completely unsupported; not ideal, and instability aside, a decent side-hit or fall could easily tear the rivnuts clean out.

Solutions like Grin Tech's 'Triple Bob' look good but I hadn't reckoned on the Mundo's MASSIVELY ovalised tubes. I'm not convinced that strapping something to these with hose clamps would be effective or particularly safe, with there being a fair chance of the clamps crushing the downtube across its section when tightened enough to adequately fix the adapter plate. Likewise, this ovalisation also poses a risk of top-to-bottom crushing if using u-bolts or similar.

Key considerations:

- It's a heavy pack that needs good support
- Brand new frame so warranty must be preserved with non-destructive solutions
- Heavily ovalised tube sections would cause significant point-loading if hose-clamps used; can't overstate the level of ovalisation here, it really is nuts!
- Ovalisation also increases risk of crushing top-to-bottom if u-bolts or similar used
- Attachment should be secure and not look temporary as bike will be left outside schools and shops for extended periods

So, have at it! What's worked for you on these frames? Thanks in advance

 

[Manbeer]

Wolf Tooth B-rad 4? Use the existing twoounting holes and a zip tie up top to support the front

 

[goatman]

id put something like 4 rubber feet on the base to take the wobble out and you wount need alot of pressure from the gear clamps, theyd be more of a safety strap?

or a rubber strip down each side of the base

 

[Skizz]

Wolf Tooth B-rad 4? Use the existing twoounting holes and a zip tie up top to support the front

Thanks @Manbeer, I did consider that but want to try and keep the stack height as low as possible. I'v actually just ordered the Double Bob as been advised it should be fine so long as I can use at least one of the factory bottle-bosses to stabilise it and reduce the need to tighten the hose clamps so much.

id put something like 4 rubber feet on the base to take the wobble out and you wount need alot of pressure from the gear clamps, theyd be more of a safety strap?

or a rubber strip down each side of the base

That's a good idea, thanks. Having decided to take a chance on the Double Bob (not Triple Bob, Grin advised double was best for the Hairon) I'll use some frame protection under the adapter plate and some rubber spacers under the unsupported lower portion of the pack's mount, the aluminium connector/fuse housing.