ROCKBROS Bike Frame Bag Waterproof Bike Triangle Bag Bicycle Under Top Tube Bag Corner Pouch Storage Bag Approx. 3 Litres for Cycling Accessories

I bought this specifically hoping it would make a good bag for an ebike controller. I bought a front hub motor wheel kit to convert my bike to electric. It is the "old school" kit with a big controller with lots of wires for plugging in the various components. If you know what I am talking about you realize those are hard to contain cleanly just because the wires are numerous. This bag worked out perfectly - the controller and all the wires fit in nicely and best of all should you need to replace a component you just unzip the bag, find the wire you need and swap out the component (throttle, PAS etc.).The one thing I was not crazy about was the mounting straps they provided but a 1" Velcro One Wrap strap allows you to perfectly customize your length and gives you a very clean install. When I first tried out my ride I noticed the controller was bouncing a bit in the bag and rattling against the stiff bottom. I put some chunks of foam packing material under the controller and added a couple of cinch straps around the bag for extra security and now the setup works perfectly, holds everything inside cleanly and gave me a really clean looking install overall. The bag is nice quality and should last as long as I have the bike. I can't vouch for the waterproof aspect but I never feel great about having an ebike out in the rain anyway so unless I get caught in a surprise rainstorm I'll never worry about that.100% perfect for my intended use here. 5 stars all the way except for the mounting straps but the Velcro One Wrap works far better anyway.

Have this Rock Bros frame bag mounted underneath the boom on my recumbent trike as I carry a large power pack that can recharge my phone for many hours/days. Also carry a cloth rag, gloves for when working with the chain, a chain tool. Room for more, with easy access.In my photos the main compartment is on the right side, while the thinner pocket is on the left side. The material can be cut to allow easy access from both side, as per the vendor's suggestion.The straps are plenty long enough for square or rectangular booms, even larger round booms. And I appreciate the low height of the bag so it does not catch on brush underneath. Can only want these to come in various colors as black is overdone. There are no elastic cording on the frame bag, only the orange bag from Rock Bros (above). ASIN B0D4YD4ZT8

The bag is sturdy and has plenty of space. It looks nice on my bike.The only downside is the straps are made of a strong, rigid material which can cause damage to the finish on your bike. I saw some other reviews with the aftermath of this. However, I hot glued some felt to the inside of the straps to prevent abrasions on my bike. (Pictured) It would be nice if the manufacturer did something like this. Or even just made one entire side the strap the soft loop of the Velcro.Anyway, I like the product but altered it to spare the paint on my frame.I wanted the 4L size but I’m glad I went with the 3L size due to the water bottle cages. The 3L is just the right size for not interfering with the bottle. (Pictured)

I have not evaluated the water resistance, only the fit and apparent quality. We will see if it holds up.This bag is almost a perfect fit for a Bosch powerpack 400 or 500 frame mounted ebike battery. Wish the zippered opening was just a tad bigger, but it works with some wiggle. The bag itself is nicely made with many mounting loops, so it is extremely secure on the frame. Using it for gear works too, it's very roomy without being too huge for the bike frame. My new favorite bicycle bag company.Many reviews mention poor water resistance despite the bag claiming to be waterproof. I don't really need it to be waterproof but I would prefer it and pay for it. Now, at this price level they could simply remove the claim and it still would be a great bag. Alternatively, make it truly waterproof and increase the cost as necessary.

Posting these early in case they can help someone else.Both bags from Rockbros. Both come with 5 hook and loop fasteners, (1 front, 1 rear, 3 on top) with some flexibility on exact placement. Both have a zip opening on each side - right hand side to the main compartment; left hand side to a slim pocket. Right hand side is full height, left hand side (because of how it’s bonded) is about 1/2” shorter than the bag.Both well made, look to be shower proof and both have there attachment points bonded to the main bag (not stitched).This bag (the larger one) is sufficient for tube, tools, small pump, first aid kit, snacks and a change of top. Slim side may be good for band aids, very slim lights, wipes, bandana and is large enough for a pro sized smart phone.Being larger is does sit on my front water bottle and I’m either going to have to move that to the underside or purchase a shorter bottle.

needed a bag to store my bike's repair tool but its always a challenge with a step thru bike. so with some adjustments, was able to mount this to the seat post where the watter bottle normally goes. it doesn't flop around & fit all the stuff.

The bag seemed to be good quality. I wanted to carry a spare eBike battery in it, but it did not fit. The battery is 17 inches long and since the product description says it is longer, I assumed it would work. However the zipped opening is on the side not on top or bottom, and it does not open all the way. So, the bag ended up being 2-3 inches short to get the battery inside it. I guess if you want to put a few small things inside, as long as they are not too long or two wide to fit through the unzipped opening, it would be a good enough product, but certainly not if you have one long items like an eBike battery or other such items. They won’t fit. The velcro to secure it to the bike seems alright, but for a heavier item I would put additional zipped tie or velcro strap.

Another great rock Brothers product as always! This frame bag fit my 2005 Trek 1200 C perfectly. Looks great and has a ton of storage space too.