Battery Triangle Bag - Carbon Frame

[hias9]

Does anybody have experience with using a heavy triangle battery (15-20lbs) inside the triangle of a carbon fibre MTB frame?

I don’t have much experience with carbon fibre frames unfortunately.
What I am afraid of it that the carbon tubes are not designed to handle the loads created by a heavy battery inside a triangle bag when riding offroad.
I am talking about XC frames of known brands.

 

[COAR]

As long as you're well below the max rider weight for the bike, I wouldn't worry about it. You might want to consider if you really need a battery that size though. Unless you're doing mega rides of 30-40+ miles or want to ride all the time at max assist, it's a waste.

 

[hias9]

I would consider 30-40miles a short ride, so yes I need a battery of that size. When doing short rides (<50miles), I have another smaller triangle battery which I could use for the short rides to save weight.
Is it possible to sit on the top tube of a carbon frame? If yes, I think a triangle battery should not be a problem.

 

[markz]

Triangle bags would suffice, Luna might sell one, I dont think em3ev sells on but I could be wrong.
Be easy enough to make one yourself if you half ass sew and can setup a sewing machine, key is to know someone with a sewing machine and they could set it up for you, half the battle is done. Doesnt have to be exact, can be crude so long as the general dimensions line up close enough to the frame tube lengths. Probably get 2m of suitable off-end fabric in the sale bin for cheap, then grab some velcro and a zipper and go to it. I bet one could sew one up for $25. Then you can sew up clothing that needs it like ripped jeans.

 

[COAR]

I would consider 30-40miles a short ride, so yes I need a battery of that size. When doing short rides (<50miles), I have another smaller triangle battery which I could use for the short rides to save weight.
Is it possible to sit on the top tube of a carbon frame? If yes, I think a triangle battery should not be a problem.

Yes you can sit on the top tube without damage I could and did when I had my carbon intense recluse (although that's a little burlier than the standard XC bike). If static body weight was enough to damage a frame, you'd hear stories left and right about them breaking on even mild trails.


As for making a bag, I think your average home sewing machine might have difficulties with fabric that's sufficiently thick to be durable enough to hold 15lbs offroad (not to mention attaching the velcro straps). I tore out 2 frame bags carrying a 5lb battery offroad, and personally a DIY bag I made would look pretty haggard and I would have doubts about its longevity.

 

[LewTwo]

As for making a bag, I think your average home sewing machine might have difficulties with fabric that's sufficiently thick to be durable enough to hold 15lbs offroad (not to mention attaching the velcro straps). I tore out 2 frame bags carrying a 5lb battery offroad, and personally a DIY bag I made would look pretty haggard and I would have doubts about its longevity.

A machine that is made to handle six layers of denim should suffice (i.e. Singer 4423 series with denim needles). Some sort of tent material such as Sunbrella dacron would likely be best. The nominal battery weight is not the problem. The problem is the deceleration at the bottom of a drop that can reach several G's. That 15 pound battery can quickly become a 60 pound force trying to tear its way out. I should imagine that minimizing the horizontal seams and reinforcing with webbing might be needed.

 

[markz]

Its the little vibrations and such that come along with hanging something off a top tube.

Be careful if you have holes in the tube for cabling, I had a Townie Electra 21D (Aluminum frame) crack right at the hole near the seat tube. I had batteries hanging off it with duct tape, zip ties and hose clamps. Weight wise, well whatever a dolphin case battery 52V 15Ah weights x 2.

Are their carbon fiber frames with holes in them for cabling? If so be careful, I dont think I ever seen a cf frame with holes in it for cabling though I never look at frames, and skip over anything cf.

 

[2old]

I rode (BBS02) off road for four or so years with a 52V, 10 ah "rectangular" battery, and a Luna bag which was well padded with Styrofoam in order to protect the battery from the severe vibration of a hardtail. The system worked perfectly with the consideration that the paint was worn off the frame in several places. FME, I would not use a frame bag with a carbon frame.

 

[COAR]

I should imagine that minimizing the horizontal seams and reinforcing with webbing might be needed.

Horizontal seams and along the zippers are exactly where mine failed (as well as the straps on the 2nd one). 1st was a $10 bag, 2nd was 3-4x that. I got less than 5 miles from bag 1 on moderate single track, and <20 from bag 2 on rougher trails. I will say this was partially [mostly?] my fault for stuffing a battery in there that was a bit too bulky for the bags - i.e. it stressed them before I even started riding.

#1

#2

I rode (BBS02) off road for four or so years with a 52V, 10 ah "rectangular" battery, and a Luna bag which was well padded with Styrofoam in order to protect the battery from the severe vibration of a hardtail. The system worked perfectly with the consideration that the paint was worn off the frame in several places. FME, I would not use a frame bag with a carbon frame.

I put some heavy duty clear 3M vinyl tape on rub spots. I use it as a chainstay protector as well.

 

[markz]

Get the right fabric, with the right thread and proper thread pattern (stitch pattern) and they probably sell some seam glue or other backing product to help reinforce the seams. I see where yours ripped there is like a thread pattern or whatever you want to call it like a stitch every 1/4 inch needs to be way more stitches then that, I guess thats what its called stitch pattern.

I'd sew the velcro supports all the way down the side to the middle of the very bottom, and do a lot of supports like that that wrap around the top tube. One every inch, then the velcro takes some of the bouncing weight of the battery and its spread out on the velcro supports.

 

[2old]

The Luna bag was very well made and pretty inexpensive ($20 - $30 at the time). COAR has a really good suggestion. Protect the battery well (I basically immobilized mine in the bag) and protect your frame with some sort of Mylar or equivalent.

 

[hias9]

I have some triangle bags and for crash protection I use a carbon fibre plate + closed cell foam.
But I am worried if the XC carbon frames can take the dymamic load of a 15-20lbs triangle battery when riding offroad (no hard offroad riding with this bike however)

 

[COAR]

I have some triangle bags and for crash protection I use a carbon fibre plate + closed cell foam.
But I am worried if the XC carbon frames can take the dymamic load of a 15-20lbs triangle battery when riding offroad (no hard offroad riding with this bike however)

You can probably find some stress models of various frames if you look hard enough. Unless it's compromised, carbon is extremely strong. A lot of frames will say they're meant for <225-250lb riders. A 250lb rider is going to put far more stress on the frame than a 150lb rider with 15lbs of batteries. Look at bikepackers too - some of those guys will really load up the bike with significant weight. I'm not into bikepacking but I've heard the Salsa Woodsmoke (among many others) is used for that, and that's carbon.

Also, if durability is a major concern, why not look at steel or titanium? Can't speak for Ti but steel is strong and has nice riding characteristics (and probably acceptably light if you're putting 15+ lbs of batteries on there anyway).

 

[2old]

Another good point unless you already have the frame. I have used an inexpensive steel frame (fortunately rides like a dream), but hardly notice it with the motor. So the bike weighs 50 or so pounds vs 46 - 47 with a lighter frame; guess how much that means when I plant my 180 on it?

 

[tomjasz]

The Luna bag was very well made and pretty inexpensive ($20 - $30 at the time). COAR has a really good suggestion. Protect the battery well (I basically immobilized mine in the bag) and protect your frame with some sort of Mylar or equivalent.

The Luna bag totally sucksThe stiffener material is cheap cardboard. Pure junk.

 

[tomjasz]

Falcon EV is a far superior triangle bag.

 

[LewTwo]

Another good point unless you already have the frame. I have used an inexpensive steel frame (fortunately rides like a dream), but hardly notice it with the motor. So the bike weighs 50 or so pounds vs 46 - 47 with a lighter frame; guess how much that means when I plant my 180 on it?

48 to 64 ounces ???

That amount of mass does not mean much combined with a rider and cargo. It can mean much more when it comes to things like carrying it up stairs or trying to lift it onto a maintenance stand. A lot of e-bikes weigh in at more like 60-75 pounds (especially the commercial ones) and to get the weight down to to the 47 to 50 you reference requires looking at every aspect.

 

[motomech]

I used a falcon EV for quite a few years, 6 or 7 i think.
The trick is to support the batt.s from underneath so the weight isn't on the straps.
Mine was starting to unravel at the seams in places, but it never split. The Az sun was getting to the fabric, but that would be the case with any soft bag.
Overall, I liked it with a few nit-picks.

 

[2old]

The Luna bag was very well made and pretty inexpensive ($20 - $30 at the time). COAR has a really good suggestion. Protect the battery well (I basically immobilized mine in the bag) and protect your frame with some sort of Mylar or equivalent.

The Luna bag totally sucksThe stiffener material is cheap cardboard. Pure junk.

You've denigrated Luna out of some sort of vendetta. I used their triangle bar for six years and it worked perfectly. That's what is being reported; not some childish BS.

 

[tomjasz]

Good to read at least one has lasted.

 

[tomjasz]

Of the four I own, the Falcon EV has proven to be more durable. Followed by EM3ev.