Mac in a Sac Speedpro Waterproof Backpack Review

With a large-capacity running vest sitting high on the mandatory kit list for my upcoming Rat Race event, I’ve been on the lookout for something that ticks the boxes without weighing me down. I recently got my hands on the Mac in a Sac Speedpro Waterproof Backpack, and after a few weeks of putting it through its paces on my training runs, here are my thoughts.

Quick Overview

• 20L capacity with a lightweight, streamlined design
• Fully waterproof with taped seams and 5,000mm protection to keep your gear dry
• Two front bottle pouches designed to carry 500ml soft flasks
• Roll-top closure and multiple zipped compartments
• Adjustable sternum straps, pole attachments, and a built-in safety whistle
• Reflective detailing for low-light visibility
• Made from durable, eco-friendly ripstop nylon (PFC & PFOA free)

My Experience with Mac in a Sac Speedpro Waterproof Backpack

I’ve been testing the Speedpro on a few of my longer training runs, and overall it’s been a solid bit of kit. It’s clear from the first use that this pack is built for distance. It’s comfortable over several hours, has loads of storage, and most importantly, keeps everything dry. That waterproof design is a big plus, especially when you’re running in the kind of weather we get here in the UK.

Storage-wise, it covers all the bases. The main compartment comfortably fits a 2-litre water bladder, and the two front pouches on the straps are designed to hold 500ml soft flasks. Between the two, you’ve got more than enough hydration for long days out. I was also impressed that the zipped pockets on the shoulder straps are large enough to fit a big phone like the Galaxy S25. That’s a small detail, but it makes life easier when you want quick access to maps or to snap a photo mid-run.

That said, I’ve found it can feel a bit overkill on mid-length runs when I’m only carrying the basics, water, some snacks, and my Ultralite waterproof jacket and trousers. Because it’s designed to carry a decent load, it can be a bit tricky to adjust the fit properly when it’s not full. I’ve noticed some bounce when I’m packing light, and it takes a bit of tweaking to get it sitting just right.

One of the features I really like is the side stretch pockets. They’re perfect for quickly stuffing a waterproof layer or grabbing something on the go without needing to mess about with the roll-top. Speaking of the roll-top, it’s great for keeping everything dry, but not the quickest to open in a hurry. For smaller items like your wallet or keys, there’s a zipped pocket on the front that’s much easier to access and has come in handy more than once.

Even with a couple of small niggles, I’m a big fan of the Ultralite Venture range from Mac in a Sac, and the Speedpro definitely holds its own. It’s not the pack I’d choose for short runs or fast efforts, but for longer trail days or something like Man vs Coast, it fits the bill. If you’re heading out for a big day or even a lightweight multi-day adventure, this pack is a great option.

Mac in a Sac Speedpro Waterproof Backpack Pros and Cons

Pros

• Easily carries up to 3L of water (2L bladder + 500ml flasks)
• Fully waterproof, ideal for unpredictable UK weather
• Comfortable fit with minimal bounce, even when fully loaded
• Plenty of storage options

Cons

• Feels a bit large for shorter or minimalist training runs
• Roll-top can be fiddly to open mid-run if in a rush

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I was kindly gifted the Mac in a Sac Speedpro Waterproof Backpack to test and review. My review is independent of the supplier and reflects my own unbiased opinions. Some of the links on this page are affiliate links, which means I may receive a small commission if purchases are made through those links at no additional cost to you. You can read my affiliate disclosure in the privacy policy.