Help! Tube-mounted battery brackets, adaptors etc. - what options are there?

[Peddlin' Pedro]

Got a new frameset on the way and unlike my last project which was built on a nine-year-old bike, I obviously can't just insert extra rivnuts in the downtube to mount my powerpack without invalidating my warranty.

The new frame is a Yuba Mundo, to which I need to fit a 17.5 Hairon pack on the downtube. There's no way I'd trust something this heavy to just the two existing bottle bosses, even in a steel frame. I've seen the Grin 'Bottle Bob' and 'Tripple Bob' mounts but I'm keen to know what other solutions people have found that are readily available and non-destructive, both off-the-shelf and DIY options.

I also have a mate who's always after excuses to run his 3D printer so that's a potential source of bespoke parts.

So far my strongest contender is something like the pic below (pinched off Endless Sphere): large stainless hose clamps, sheathed in heat shrink and locked around a nut to insert into the recess underneath the battery's mounting plate.

The frame does not have any additional bosses/cage mounts to which I could fit additional supporting hardware so any solution needs to be clamp-based, clamping around the downtube itself.

Thanks.

 

[Raboa]

My frame has 2 crud catcher bolts on the down tube, I put a hole and grommet in some webbing, the webbing is clamped with the down tube bolt / washer and buckled on the top of the battery.

 

[Peddlin' Pedro]

My frame has 2 crud catcher bolts on the down tube, I put a hole and grommet in some webbing, the webbing is clamped with the down tube bolt / washer and buckled on the top of the battery.

Thanks. That's a good idea but don't have any under-tube bosses, which is mildly irritating as the Ute frame that I'm replacing did.

 

[Swizz]

Have you not considered the void behind the seat tube?

Have a look at how Tern mount their batteries. I suspect you may have enough room back there...and if your friend has a 3d printer even better.

 

[Gavin]

A much stronger variation on the hose clamp would be 2x exhaust u-clamps, clamped onto whatever tube you want to mount the battery.

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Just use the u-section bit (discard the pressed steel bit) and slide rubber fuel hose over it to protect the frame. Then make a flat alloy plate of the same size as the battery cradle, with 4 x holes in it (2 for each u-clamp to fit through). Screw the plate on top of the downtube with the u-clamps underneath, sandwiching the frame inbetween. Put a sheet of rubber under the alloy plate to protect the frame.

If you use countersunk nuts, the top of the alloy plate will remain flat, allowing you to bolt the battery cradle straight on top.

Looking at the design of that frame, I'd be putting the battery on the rear of the seat post tube and putting an extended flat plate on the front of the rack or rear frame tubes. This would make it harder to get the battery out, thus preventing theft....

 

[Peddlin' Pedro]

A much stronger variation on the hose clamp would be 2x exhaust u-clamps, clamped onto whatever tube you want to mount the battery.

Just use the u-section bit (discard the pressed steel bit) and slide rubber fuel hose over it to protect the frame. Then make a flat alloy plate of the same size as the battery cradle, with 4 x holes in it (2 for each u-clamp to fit through). Screw the plate on top of the downtube with the u-clamps underneath, sandwiching the frame inbetween. Put a sheet of rubber under the alloy plate to protect the frame.

If you use countersunk nuts, the top of the alloy plate will remain flat, allowing you to bolt the battery cradle straight on top.

Looking at the design of that frame, I'd be putting the battery on the rear of the seat post tube and putting an extended flat plate on the front of the rack or rear frame tubes. This would make it harder to get the battery out, thus preventing theft....

Decent suggestion, thanks. I did consider u-bolts of some sort but not knowing the wall thickness on these tubes I'm reluctant to use them for fear of crushing, which is easily done.

The back of the seat tube isn't easily accessible as the angle where the top-bars of the rack meet the seatstay wishbone is too tight. There's the potential to flat-mount a pack on the chainstay wishbone area but won't know how much clearance I've got until I can measure the frame up. I'd also prefer to keep the pack in the main triangle for better weight distribution as this thing's going to get heavily loaded up.

I remember seeing a post somewhere on the forum where someone had 3D printed some battery supports (not mounts) and wondered if these could be adapted. Can't find the post though.

 

[Raboa]

Hi, what about these (not stainless steel though), they do different sizes, wrap a tape measure around your downtube and battery.

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Join two of these together:

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[egroover]

I use a couple of the 50mm velcro straps, works well for me

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[Nealh]

The sturdy Velcro strap solution is a good option, no extra 3d printing or hole drilling needed.

 

[Chainring]

https://www.ebay.co.uk/itm/35MM-TUBE-SADDLE-CLIP-304-STAINLESS-STEEL/322423744225 I had been looking at these, combined with an ally plate, as I've had the same thoughts on a new build.

 

[Peddlin' Pedro]

Thanks for all the suggestions and sorry for not responding sooner. Took a while to source the frame, which we now have. The challenge now is that the tubes are MASSIVELY ovalised (and tapered), more so than anything I've ever seen. They're twice as wide as they are tall which presents obvious challenges in clamping without compromising tube integrity.

My concern now with mounting anything using hose clamps is that this ovalisation will cause significant variance in pressure at points around the tube; see illustration showing how something like Grin Technologies 'Tripple Bob' might work with a tube of this profile. Obviously a rounder section would result in more even pressure around the tube.



Another key consideration is that the bike is a daily runabout and workhorse and will spend a reasonable amount of time outside schools and shops etc. As such, any mounting solution needs to be secure, so velcro or other visibly temporary options are out of the question.

Looking increasingly likely that I'll need to risk the warranty and just insert extra rivnuts as I did with the Ute. On the up side, should there be other issues with the frame within the warrantied period and they decide to quibble, it's made of chromo steel so is relatively easy to get repaired.

Still open to other suggestions though so keep 'em coming!

 

[Raboa]

Hi, i wonder if it worth getting a bag to fit in the frame front triangle / middle of frame, that way any webbing / attachments would be hidden. People may just think that any visible webbing is part of the bag, the bag zip could be zip tied together or some other locking device.

 

[Swizz]

Now you have the frame to hand with your battery, have you reconsidered my Tern'esq suggestion?

Am only asking as I did an image search for an electric Mundo and this one popped up with a silverfish battery in the same position. Have no idea how different a silverfish case is from a HL but it may be worth offering your battery up just in case?

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Price: $2599.00 | Model Year: 2012 | Sturdy cargo bike with add-on electric kit that struggles in some areas

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[vfr400]

Now you have the frame to hand with your battery, have you reconsidered my Tern'esq suggestion?

Am only asking as I did an image search for an electric Mundo and this one popped up with a silverfish battery in the same position. Have no idea how different a silverfish case is from a HL but it may be worth offering your battery up just in case?

2012 Yuba elMundo Review | ElectricBikeReview.com

Price: $2599.00 | Model Year: 2012 | Sturdy cargo bike with add-on electric kit that struggles in some areas

electricbikereview.com

That looks like an Ezee battery and motor.

It looks like a really hood solution for the battery location. A few pipe clips, a couple of cross-strips and you're done.

 

[peter.c]

If the battery will fit in the space behind the seat that will be a good use of a dead space
try a flat piece of wood as a mounting board/ plate the hailong base will screw on to it and if it works make it in acrylic sheet an exhaust clamp will make a strong mounting and spread the tension over the surface

 

[Peddlin' Pedro]

Now you have the frame to hand with your battery, have you reconsidered my Tern'esq suggestion?

Am only asking as I did an image search for an electric Mundo and this one popped up with a silverfish battery in the same position. Have no idea how different a silverfish case is from a HL but it may be worth offering your battery up just in case?

2012 Yuba elMundo Review | ElectricBikeReview.com

Price: $2599.00 | Model Year: 2012 | Sturdy cargo bike with add-on electric kit that struggles in some areas

electricbikereview.com

Doesn't fit I'm afraid. The frames have changed quite a bit between successive generations and the the latest (V5) has tighter angles and thicker stays (and better steel, so that's nice). Doesn't fit on the chainstay-wishbone either as it's not quite long enough. The other challenge is that I have to charge the battery off the bike so it needs to be accessible with minimal faffing, and the main triangle is still the best location for weight distribution/handling.

Managed to speak with a couple of people today who are familiar with the Mundo and they felt the Grin option would probably be okay if I could use at least one of the existing bosses to stabilise the plate and reduce the need to tighten the hose clamps too much. I think for the sake of £35 I'll give it a go and if doesn't work it'll reappear in the classifieds section shortly .

Seen too many frames damaged by overenthusiastic tinkerers bolting, clamping or even riveting random stuff to their bikes and I think most people underestimate how easy it is to knacker a frame by applying forces in directions/locations it wasn't designed for. That's why I'm being so cautious, especially on a brand new and not particularly cheap frameset.

UPDATE: Grin advised that the Double Bob was the better option for the Hairon pack, rather than the Triple Bob.

 

[Swizz]

Am sure one of those will be fine. In fact in some ways may be a good thing being mounted forward for even distribution.

I fondly remember having a go on an early one. It was riding on Big Apple tyres and they were really nice!

 

[Peddlin' Pedro]

Am sure one of those will be fine. In fact in some ways may be a good thing being mounted forward for even distribution.

I fondly remember having a go on an early one. It was riding on Big Apple tyres and they were really nice!

Big Apples are great aren't they. Pretty much started the trend for oversized road tyres. Have to say the Super Moto X 2.4s are also pretty good. I remember riding an older Mundo too and it must have been a while ago as it was definitely the older tube layout, and agriculturally heavy! Don't remember the main tubes being quite so squashed but probably just wasn't paying attention. Think they were still making them in Germany then too. Just waiting for the battery mount, centre-stand and speed sensor extension and then I can get started. Buying and waiting for bike parts at the moment really is a massive pain in the bum.

 

[Swizz]

Big Apples are great aren't they. Pretty much started the trend for oversized road tyres. Have to say the Super Moto X 2.4s are also pretty good. I remember riding an older Mundo too and it must have been a while ago as it was definitely the older tube layout, and agriculturally heavy! Don't remember the main tubes being quite so squashed but probably just wasn't paying attention. Think they were still making them in Germany then too. Just waiting for the battery mount, centre-stand and speed sensor extension and then I can get started. Buying and waiting for bike parts at the moment really is a massive pain in the bum.

Innit. Be worth the wait tho!