First Impressions: Ortlieb Seatpost Bag

Ortlieb bags are famous for their durable, waterproof construction. The German-made seat bags and panniers are a favorite with all-weather riders who want their gear to remain dry in adverse conditions. And now, Ortlieb broadens their product range with the introduction of the company’s Seatpost Bags.

Unlike their original seat bags, Ortlieb’s Seatpost Bags attach directly to the seatpost. The integrated mount fits ‘posts from 25.4mm to 34.9mm diameter. A quick-release strap allows easy installation and removal. Ortlieb offers the Seatpost Bag in two sizes: small (1.5kg max load, 1.5 litre capacity), and medium (2.5kg max load, 4 litre capacity). Both bags feature high-frequency welded seams, waterproof fabrics, hi-viz reflective accents, and tabs for attaching blinky-style lights.

The Seatpost Bags utilize a ratchet-type design that’s similar to the closures found on many cycling shoes. This tool-free system allows quick-and-easy installation and removal, while still providing a secure interface with the seatpost (Ortlieb does not recommend using the Seatpost Bags with carbon or aero seatposts). The mounting bracket features a soft rubber insert which helps reduce slippage, as well as protecting the seatpost’s finish. During our testing, we had no difficulty swapping the bags between 27.2mm and 31.6mm seatposts.

Even when loaded to their respective max capacities, both bags remained securely attached and noise-free. The packs themselves did exhibit some minor flex, but it wasn’t noticeable during actual riding (even on bumpy dirt roads/trails). The dry bag-style rolled closures did an outstanding job of keeping the bags’ contents dry, and unlike zippers, didn’t become jammed when exposed to grit and grime (of which there was no shortage). gravel grinder Ortlieb seatpost bag Black Mountain Cycles Selle Anatomica Paul Component Engineering CamelBak Panaracer Shimano H+SON
Ortlieb’s medium-size Seatpost Bag performing double-duty as a mudguard on a sloppy weekend ride.

For day rides, centuries, and light commuting, the medium Seatpost Bag would be an excellent choice. The pack’s internal mesh pockets help keep items organized, and the elastic cord can easily accommodate a light jacket or other clothing. At 442g, it’s lighter than a dedicated rack-top bag, and can be easily removed when not needed. While the smaller Ortlieb Seatpost Bag is heavier (243g) than a conventional seat pack of comparable capacity, the former’s mounting system makes it compatible with hard-to-fit saddles such as those with springs or I-beam designs.

Disclosure: Ortlieb USA provided review samples for this article, but offered no other form of compensation for this review.

12 thoughts on “First Impressions: Ortlieb Seatpost Bag

  1. I love the idea behind the design of these bags. The sealed zipper on my Bontrager works but is hard to open and close.

    I wonder how the plastic seat post attachment will hold up over time after some hard bumps. I know there are some fast and rough descents on the Land Run 100 course that will surely loosen or break anything if you hit a rock the wrong way.

    Can you give any estimate of much the small bag will hold based on how many inner tubes it would hold?

    1. The small bag comfortably held the following items:

      • Four 700×25/28 tubes
      • One CO2 cartridge and inflator
      • One pair tire levers
      • One Topeak Mini-9 multi tool
    1. Really pleased with its performance. It’s perfect for when jersey pockets don’t offer enough room, but a Carradice-type bag is too much. Also works well as a makeshift fender. As with all Ortlieb products, quality is excellent.

  2. Thanks for the follow up. Some reviewers (there seem to be at least a few) have stated that there is a pin in the clamp that can fall out.

    1. Hmm, interesting. I haven’t encountered that, but I will check the bags’ clamps to see if the pins have migrated.

    2. I checked the bags, and one of the pins looks like it may have shifted a very small amount (less than 2mm). I pushed it back into place with a small allen wrench, and it took more force than I expected (which hopefully means that it won’t just fall out).

  3. I am sure these are very nice bags but I think I made a right choice to go with Revelate Designs Pika instead. It is roomier (6-12L max. vs. 4L for Ortlieb) and lighter at 375 grams (measured). It is however also more expensive ($125 vs. $85).

  4. Any thoughts on thigh rub? I run my saddle far enough back that nearly every bikepacking style bag I’ve used rubs my shorts in a way that will surely destroy them in fairly short order. I’m looking for the narrowest/furthest offset back bag of this type and the Ortlieb is on my radar. Thoughts?

    1. I didn’t experience any thigh rub with either model. The bags’ lack of Velcro straps may just be what you need.

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