Araldite as filler between frame and bracket?

[MarkLeeds]

Hi Guys,

I hoping to get comments on the above, I have made some brackets to hold a battery enclosure to the downtube of my specialized enduro 2014. Unfortunately for me the down tube is an irregular oval shape. By hook and by crook I've managed to make my bracket quite close and was planning to use either rubber or aradilte (standard) to fill the last bit.

I thought araldite might work best as when fully cured it is very hard. In the event of a crash I thought it would spread the forces most effectively and prevent damage to the frame.
What do you think?

Regards Mark

Here a picture of the gap.....

https://imgur.com/a/OIAAS

[Buk___]

Hi Guys,

I hoping to get comments on the above, I have made some brackets to hold a battery enclosure to the downtube of my specialized enduro 2014. Unfortunately for me the down tube is an irregular oval shape. By hook and by crook I've managed to make my bracket quite close and was planning to use either rubber or aradilte (standard) to fill the last bit.

I thought araldite might work best as when fully cured it is very hard. In the event of a crash I thought it would spread the forces most effectively and prevent damage to the frame.
What do you think?

Regards Mark

Here a picture of the gap.....

https://imgur.com/a/OIAAS

I'd glue rubber (strip of inner tube) to the inside of the wood; at least that way if you ever need to reconfigure or replace it your frame will be free of araldite that would be a pig to remove.

[wturber]

I'd glue rubber (strip of inner tube) to the inside of the wood; at least that way if you ever need to reconfigure or replace it your frame will be free of araldite that would be a pig to remove.

Yeah - I'd go with rubber or even a strip of leather. I used leather (strips from a weight lifting belt that I wouldn't be using) between my double-leg kickstand that the chainstays it is bolted to to protect the frame from being scraped and gouged by the clamp while still providing a firm connection.

[MarkLeeds]

I was thinking of putting tape between the araldite and the frame to make removal easier. I thought perhaps rubber/ and or leather wouldnt be so great at distributing forces. A high speed off with these might result in a dented frame?

[flat tire]

Whatever filler you use probably won't be of much use structurally. You might try fiberglass. It's very inexpensive and you can be laying it up yourself in about an hour after driving to walmart. You need to sand the metal to get it to bond. Put down multiple layers and alternate them by 45* if you use woven fabric instead of chopped mat.

[MarkLeeds]

Anyone any idea how thick mtb aluminium downtubes are? Would 2mm be about right?

[dogman dan]

Rubber strips can fill that gap. Like cut up thorn resistant inner tube.

Much thinner than 2mm. Quite possibly thinner than 1mm, depending on the quality of the frame.

[spinningmagnets]

I took a quick google and it seems like Araldite is similar to JB Weld? I think it is worth trying, and if it cracks, you simply move on to something better. But...if it works, it's a quick and easy way to fix a small problem.

Perhaps mix the Araldite and then sqeeze it into a balloon? Place the balloon inbetween the frame and bracket quickly, and a short time later it has hardened into the odd shaped airspace you need filled. Worth a shot...

[dogman dan]

Yeah, anything could be used between the frame and the epoxy to make it stick to the mount, but not the frame. Piece of paper, tin foil, plastic wrap, etc.

I just always have lots of dead tubes laying around so,,,

[MarkLeeds]

I took a quick google and it seems like Araldite is similar to JB Weld? I think it is worth trying, and if it cracks, you simply move on to something better. But...if it works, it's a quick and easy way to fix a small problem.

Perhaps mix the Araldite and then sqeeze it into a balloon? Place the balloon inbetween the frame and bracket quickly, and a short time later it has hardened into the odd shaped airspace you need filled. Worth a shot...

As far as I'm aware araldite is a brand name for a type of epoxy resin. Much harder than jbweld. I google araldite hardness and it's very hard. Really like the balloon idea - thanks for that

[Buk___]

Another thought. Mouldable silicon; otherwise known as Sugru. Amazing stuff.

I used it to make heat resistant handles for a couple of my wife's large ceramic coated cooking pots that had metal handles.

It sticks very well, but peels off if need be; moulds like playdoh, but sets up overnight and turns into very firm, but still slightly springy silicone rubber that is very heat resistant. (There's a chinese clone that's a bit cheaper.)

Unlike araldite which is hard enough to dent your tubes if the box gets a good thump; the silicon rubber will absorb a lot of the impact and distribute the rest around the tube.

[MadRhino]

Whatever you are using, should be on the battery box mount to mimic the frame shape. For this purpose, cover the bike frame with plastic then mould the composite onto it until dry enough to pull off neat. Then the plastic tape can be removed from the frame, and thin padding applied to the part of the mount that will be in contact with the frame.

The Specialized Enduro frame has a lifetime crash guarantee. You don’t want to mess with the frame integrity.

[MarkLeeds]

Thanks for all your suggestions, I've uploaded another couple of pics to illustrate what i'm trying to do. The big picture is I'm a keen amateur off road enduro motorcyclist and thought I'd build an offroad electric mtb for training. I've tried to over engineer my project as im expecting many offs... some big. Im starting to get a bit worried about my battery box attachments as the down tube thickness is only 1mm give or take. Last thing I want to do is damage the frame. My brackets are only 12mm wide- the max my local laser cutting company can do.

Do you think some kind of steel sleeve might be a good idea, maybe a 1mm steel one? This would distribute the forces. Maybe some araldite and rubber on top?


https://imgur.com/a/00UlI

https://imgur.com/a/zDpqA

https://imgur.com/a/JwYkD

[Chalo]

Isn't that going to foul your pedaling? I'd never be able to live with a battery box there.

[MarkLeeds]

It's fine the battery box is no wider than the cyclone - doesn't interfere.... I did loads of testing

[dogman dan]

Looks great to me. only one thing, just make sure you cannot possibly have the box contact the front wheel. Likely ok, but bear in mind, land a jump a bit wrong, and you will bottom out that fork, and your wheel will not be perfectly straight. That will be even more fun if the battery box stops the front wheel.

Looks like it won't, but just saying be sure it cannot happen. If a fender mounted under the top of the fork clears, you are all good.

[MarkLeeds]

Yeah, i've used about 2 football pitches worth of plywood trying loads of different combinations I think the clearances are ok - fingers crossed.

What do you think of my sleeve idea? I have ordered some 0.7mm thick steel sheet from ebay. I plan to bend it round the down tube creating a kind of outertube/ sleeve. The idea is to increase the thickness of the downtube. This would have make the downtube much stronger by increasing it's thickness by 0.7mm. As far as I'm aware, thickness for thickness, steel is much stronger than aluminium.

[flat tire]

You need to account for stiffness as well as strength, and you'd probably be better off adding fiberglass to the bike all things considered. Composites. They're awesome. Fiberglass strength / weight will be in the neighborhood of the aluminum especially if you use woven fiber instead of chopped mat.

The downtube sleeve idea could work though you should be aware bending that sheet into a nice cylinder will probably suck unless you have a roller. Are you going to hold it on with hose clamps? Anyway, that will be a lot heavier than fiberglass.

[Buk___]

What do you think of my sleeve idea?

I think that steel is far more likely to damage your frame than the plywood.

[MarkLeeds]

You need to account for stiffness as well as strength, and you'd probably be better off adding fiberglass to the bike all things considered. Composites. They're awesome. Fiberglass strength / weight will be in the neighborhood of the aluminum especially if you use woven fiber instead of chopped mat.

The downtube sleeve idea could work though you should be aware bending that sheet into a nice cylinder will probably suck unless you have a roller. Are you going to hold it on with hose clamps? Anyway, that will be a lot heavier than fiberglass.

I like the fibre glass idea, although i'm going to try the steel first as it's already on its way. Thanks for the hose clap suggestion. I think that might be a great way to bend the steel to right shape. I thought I might even use a couple of layers (0.7mm +0.7mm) to add even more strength

[MarkLeeds]

What do you think of my sleeve idea?

I think that steel is far more likely to damage your frame than the plywood.

Unfortunately the plywood is not going to be strong enough as each battery pack weighs around 2.5 kg

[Buk___]

Unfortunately the plywood is not going to be strong enough as each battery pack weighs around 2.5 kg

3mm ply with a layer of fiberglass each side is very light and very strong.

[teklektik]

Don't turn that into a science project - you just have a small gap.

Go to a Home Depot or Lowes and get a foot of PVC shower pan liner sheet off the roll.

showerPanLiner.png (78.74 KiB) Viewed 767 times

The roll is 48" wide so you'll get a huge 1' x 4' piece for about $5.
This stuff is 40mil (thickish but much thinner than inner tube), very dense, and pretty incompressible. I use this to mount all manner of stuff on the bike. You can wrap a layer or two, or cut overlapping sized rectangles to put under a layer to get an odd shape fill. This stuff is amazingly rugged and abrasion-resistant -- my go-to stuff for mounting, shimming, insulating heavy battery items, etc.

[flat tire]

Did it occur to you that with mild sheet steel that thin, your wrap will at best hold your frame together after it breaks, and probably not help prevent it from breaking since the frame will be so much more stiff than your wrap?

[MarkLeeds]

Did it occur to you that with mild sheet steel that thin, your wrap will at best hold your frame together after it breaks, and probably not help prevent it from breaking since the frame will be so much more stiff than your wrap?

I think that the frame would perhaps dent and then maybe break at a later date once weakened. As far a I'm aware mtb frames gain a lot of their strength from their shape.

I'm waiting to see what the steel looks like when it arrives, I thought I might use multiple layers if it looks a bit weak. Multiple layers would also be easier to "mould" to the shape of the frame - maybe using hoseclips. Three layers would have a combined width of 2.1 mm which is going to be pretty tough.