Posted by: audaxing | May 16, 2012

Lightweight Saddlebag Substitute

I recently resurrected my titanium bike. This had donated it’s titanium seatpost to my Specialized Roubaix but now it seemed only fair and right to return the seat post to it’s rightful place.

The main reason I’d moved the titanium seatpost to the Roubaix was to use a Carradice SQR mount during PBP and qualifiers. On long rides quite a bit of luggage capacity can be needed.

The Roubaix had been supplied with a carbon post so I installed that instead. The bike wasn’t entirely without carrying capacity as it had a barbag. But when I had the Elenydd 300km planned I needed a bit more.

A carbon seatpost won’t take SQR block. Well, it might but there is a risk of creating a stress riser in the carbon where the metal clamp tightens on. And I need the seatpost to be as reliable as possible, I’m not going looking for trouble…..

So I had to find an alternative. I had a 6L bag I don’t use much. This could attach to the back of the saddle nicely. But the reason I don’t use it is that it isn’t quite big enough.

I couldn’t fit a rack, and anyway that would be (relatively) heavy. A rack is great for panniers but I just don’t need that amount of stuff.

Carradice do do a “bag supports” of various sorts, for instance the “Bagman Q/R Sport” but these don’t suit my SQR Tour bag, which only really works with the excellent SQR system

So I started to consider non Carradice bag options. They had to be waterproof, and fairly light would be good as they are going on the Carbon bike

Then I came across the “Ultralight bicycle touring” blog One of the of many ways of cutting down weight on their touring bikes is to try new and interesting luggage carrying methods.

Inspired by lightweight touring, I’ve got an Alpkit dry bag. This is attached through the bag loops on the saddle. I have an 8L and a 13L sized one to try.

The weight difference between this and a Carradice SQR tour is significant. The Carradice bag, excluding the plastic clamp that fits the seatpost is 1100g. The Alpkit dry bag, size 8L is 150g. So the total difference is around 1Kg.

Extremely waterproof and about the right size, the only little issue I have with it is that it takes a couple of minutes to attach instead of instant on/off with the SQR

I’ve done hundreds of km with it now and it seems to do the job, even in the wet

Dry bag in action

Alpkit Dry bag in action, Snow on the Mountains behind

UPDATE: If you want a more “pro” job of a saddle bag from an Alpkit drybag then just look on Alpkit’s website (I didn’t) Here is an article about making a saddlebag requires sewing machine, seam sealant and manual dexerity…


  1. Very interesting – have an SQR Tour on order, but not entirely convinced it’s right for me and due to lack of stock I could still cancel the order. This is tempting. Couple of Q’s

    Do you find it knocks the back of your legs at all? Kind of looks like it might

    Would you consider the 8L or the 13L suitable for an LEL or PBP?

    • It does brush the back of the legs but personally this doesn’t bother me.

      It would be OK for PBP or LEL. Last PBP I used an SQR Tour and a Medium sized Ortlieb bar bag, so I had a lot more space than 13L however.

      • Cool, thanks for the feedback. I have the small Ortlieb (2.7L I think) and have a Ti post. So maybe the SQR is still going to be my better option. Will keep this one in mind though.

  2. I’ve been toying with this exact same concept lately! One idea I’ve been toying with is attaching a piece of narrow hard foam to the seat post. This might push the bag back enough to avoid brushing your legs.

    • I did a few long rides with the drybag attached with vecro cable ties and/or elastic straps
      It worked ok, but the metal of the B17 loops cut through the straps and the straps cut into the bag

      I’ve now switched to a “Carradice Sport Bagman QR” which is a sort of very minimal rack designed to support a saddlebag from below. The way it works means that the dry bag can go on and off the bag in a few seconds. The disadvantage is that it weighs a few hundred g, but overall I still have a very much lighter bag than before

      • Liking that idea a lot – especially since SQR Tour are in short supply. I reckon I may give it a try. Ta for updating the thread.
        – Rob

  3. […] 5)Lightweight Saddlebag Substitute Stuff about using a dry bag as a saddle bag. People hate heavy luggage. Although there is no real solution to the “light bike bag that is water proof, cheap and last forever” there is interest in any possible ideas about it […]

  4. Valid approach, but I find that you have to count not only the time saved by lighter equipment, but also the time lost by worse handling. I see people fiddling with drybags all the time and they seem to loose a lot of time vs. Carradice or french type front (handlebar) bags where all the content of the bag is easily accessible. Drybag is for things you need once a day.

    • Alexander, I completely agree. Usually I have a combined drybag and bar bag setup. The drybag has the bulky clothes, tools I don’t use much, spare food etc. The things I actually want (food I’m eating, maps, commonly used tools etc) are in the bar bag

  5. […] Lightweight Saddlebag Substitute People want light […]

  6. Try bridge street saddlebags , dry bag style but designed as a proper saddlebag with quick release. Weight around 400g including mounting.

    • Yes, I saw them on kickstarter. Like an Ortlieb roll top pannier but using block mount onto the seatpost. I’ll see how they look IRL, I’m sure I’ll see a few next season

  7. Dill Pickle Saddlebags etc in the states. Cost a mint but beautiful custom stuff.

  8. You mention about not using an SQR mounting on a carbon seatpost because of potential stress problems with the steel band. Doesn’t the seat lamp put the same or more stress on the post? I spoke to Carradice some time ago about this and they were fairly relaxed about using it on a carbon post

    • Lights are usually mounted with a plastic band and they are much lighter than an SQR block. The nightmare scenario with a metal SQR block is if one of the two bands looses slightly it could rub on the seat post. Yes I know I am paranoid – but that doesn’t mean that they aren’t out to get me! :)

  9. Only a thought and certainly not a criticism ! The Alpkit dry bag should be secured in a more vertical fashion not as is shown horizontally ! That way access is easier and doesn’t bounce around !

    • The way I have it now is on a Carradice sport rack and it clips on nicely in the “horizontal” manner! However, I have been considering a vertical alignment -but not for any of the reasons you give! I have been perfecting the cyclocross dismount during my morning commute and a narrower section of luggage would make this possible on the audax bike…

      • Have you looked at the Alpkit Koala ? Fits securely, easy to access ! I totally virginal as far as Audax goes but carry all of touring kit as bike packing !
        Like the idea of doing some Audax in 2015 and so far have enjoyed your posts ! Thank You

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