ROCKBROS Triangle Frame Bag (2.5 L) Review
A slim wedge for the top of the frame triangle that keeps tools and snacks off your back. ROCKBROS calls it waterproof in the title and water-repellent everywhere else, and the second word is the one to believe.
The verdictA slim, light half-frame bag for fair-weather riding. The zip and the rain are its limits.
The Amazon US listing sells this as the Medium 2.5 litre bag, 30 cm long, 19 cm at its deepest tapering to 6.9 cm, and 6 cm wide, at 6.4 oz (181 g). It hangs under the top tube on four straps and opens by a main zip, with a zipped side pocket for small items. A Large 4 litre version, 40 by 23 cm, sits on the same listing for bigger frames, so measure your triangle before ordering.
The title says waterproof, but the bullets describe water-repellent fabric and zips and tell you not to soak it in heavy rain. Treat it as a bag for a shower, and put a phone or a battery in a zip bag inside it on a wet day. At 6 cm wide it clears the knees, though one owner found it left room for only one bottle cage.
Owner reports stood at 4.0 stars across 85 ratings in October 2026, with 11 percent at one star. The sharpest complaint was a zip that stuck on its waterproof lip and came apart on the first day, and another owner found the strap positions awkward on an e-bike top tube. At $37.99 from ROCKBROS it is not the cheapest half-frame bag, so the slim profile is what you are paying for.
What works
- 6 cm wide, clears the knees
- 181 g for 2.5 litres
- Zipped side pocket for small items
What doesn't
- Water-repellent, not for heavy rain
- Owner report of a zip failing
- May leave room for one bottle
Buy it if
Riders who want tools and snacks in the frame triangle on dry or showery days, with a bottle cage still usable
Skip it if
You need a bag that stays dry in heavy rain, run two bottle cages on a small frame, or want the cheapest option
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