Seatpost or Saddle Mounted Audax Bag?

Dr_Colossus

Ok a lot of questions below following on from research on an appropriate seatpost or saddle mounted bag with the aim of audax and similar one/two day spins on a road bike. I haven’t seen an appropriate thread dedicated to the cause hence why I’m starting this.

The situation is I’ve a CF bike with a CF seatpost so the reviews/advise of some of the seatpost mounted bags are a little worrying. For instance all the Detour High Trail Seatpost Bags advertise that they’re not suitable for carbon seatposts (link below)
http://bikemart.com/product/detours-high-tail-exp-seatpost-bag-54836-1.htm
Nice looking bag/system although the 8.2 litre (13.9 litre expanded) capacity is probably a little too big? The mounting system is nice and tidy with a singular band left around the seatpost when the bag is not in use but this is the worrying factor, how stable would this be for general side movement and over rough bumpy roads when loaded with additional clothing and food. Given that all the weight/friction is on one single plastic bracket attached to a metal collar around the seatpost I’d imagine the seatpost/bracket would be in for some punishment and subject to fatigue? How much of a factor is a carbon seatpost for such a system or even an alloy seatpost for that matter?

A similar type bag and attachment mechanism is the Altura Arran Expanding Post Pack and at 5 litres expanded seems like a good size. I believe The_Tax_Man and possibly some other boardies have this bag so does anyone use it with a carbon seatpost? What’s the capacity like and how stable do you find it? The only problem with this bag is that it seems to be sold out everywhere at present, even in the CSS, which I suppose is a good sign.
http://www.cyclestore.co.uk/productDetails.asp?productID=3761

Another alternative is the Altura Aero Post Pack with a 6 litre capacity or the bigger Altura Night Vision Post pack at 10 litres. It’s hard to get an idea of size without seeing them in the flesh but the Aero Post Pack looks nice and should be more than sufficient size wise. Anyone have this bag and how do you find it, has it the same mounting bracket to the Altura Arran Expanding Post Pack above?
http://www.cyclestore.co.uk/productDetails.asp?productID=23652
http://www.cyclestore.co.uk/productDetails.asp?productID=23940

Altura doesn’t seem to specify or recommend that their Post Packs are not used on carbon seatposts and I’ve read one review that had used it on a carbon seatpost without problems although recommended a sleeve fashioned from an old inner tube as a sensible precaution. So does anyone have any contrary advice? Granted I could always change the seatpost to an alloy one but this isn’t ideal since it would further increase the cost of the bag and a carbon seatpost shouldn’t be significantly weaker than an alloy one especially since it can accommodate the weight of a cyclist.

As an alternative then to the seatpost mounted bags there are large saddle bags such as the below Super C Saddlepack from Carradice but I’m not sure how stable an 8 litre saddle bag sticking out behind the saddle would be without any sort of fixed metal attachment. Plus I’d imagine the strap fittings would lead to even more wear and rub than the KlickFix system used in the seatpost mounted bags above?
http://www.carradice.co.uk/index.php?page_id=product&under=type&product_id=34

Another alternative then would be something like the 7 litre Barley Saddlebag by Carradice but the attachements to the saddle look specific and more akin to the loops sometimes seen on the likes of a Brookes saddle. Also I don’t particularly like the look of the bag which appears fashioned after an old style satchel type school bag with the roller buckles.
http://www.carradice.co.uk/index.php?page_id=product&under=type&product_id=43
There are metal supports for attaching underneath normal road saddles (link below) for such larger type saddle bags but they seem very expensive for what they are. Granted they’d add some stability to the saddle bag but not sure how practical they are overall even after the cost involved. They do give a 10kg limit though as opposed to the 3kg limit of the KlickFix system.
http://www.carradice.co.uk/index.php?page_id=product&under=other&product_id=104

A further alternative still is the likes of the SQR clamp which looks like a more robust version of the KlickFix system since it has two metal collars around the seatpost.
http://www.carradice.co.uk/products/other/sqrclamp
The accompanying bags though seem very large though and in the region of 16 litres, the bigger the bag the more likely to bring unnecessary items.
http://www.carradice.co.uk/products/type/sqrtrax

So anyone got any advise of ideas. Overall I think I prefer the look and size of the Altura Aero Post Pack but am unsure as to the attachment mechanism for a carbon seatpost. It would be convenient to leave on my existing Topeak Aero Wedge saddle bag with the spare tube and tools and just clip on the Altura when required. Having said that though the Carradice metal supports for a larger saddle bags look more robust but also very expensive.

So much choice, if I spent as much time cycling as researching all these additional items and gear I’d be well on my way to completing my first Audax.
Thanks for reading and apologies for the length of the post.

Lumen

What do you propose to carry?

Dr_Colossus

A good question, at the moment I'd envisage mainly clothes and some food. The likes of a jacket plus an additional jersey/baselayer, leg warmers, overshoes, gloves and possibly a hat for when the temperatures change throughout the day/evening/night. Sandwiches, bars and some electrolyte tablets for sustenance and then some spare batteries for the lights for when the sun goes down.

At present I've a little saddle bag in which I've my spare tube, patches, tyre levers, multitool, phone and cash with the pump mounted to the frame. I've managed fine with this so far on distances up to 175km but with the winter setting in and hoping to tackle my first Audax with the the Dying Light 200 next month feel I'd need additional space for additional layers etc. Maybe I don't and the saddle bag and pockets of the jersey would be enough but most of the pictures I've seen of Audax riders usually carry some sort of additional bag. I guess I won't fully know what I need until I start doing them. Mission for the new year is hopefully to complete a 400.

petethedrummer

Dr_Colossus wrote: »

The accompanying bags though seem very large though and in the region of 16 litres, the bigger the bag the more likely to bring unnecessary items.
http://www.carradice.co.uk/products/type/sqrtrax

I have one of these, you are welcome to borrow it and try it out, if you're in Dublin. PM me if you want it.

I used it for commuting for a while. It didn't hit off my legs or anything and was waterproof. On the downside, if you pack it up too much it throws the handling off a bit because the weight is up so high. I suspect it would be too big for an audax. You could carry a full change of gear in it easily.

smacl

I've had the Altura Arran for about six months now, and find it very handy on long spins, particularly as I currently only have one bottle holder. Expanded it will hold a light waterproof jacket, spare top layer, spare bottle, pump, 2 tubes, 6 bars, tools, phone, spare glasses, pump, bananas, and some spare batteries, but all pretty tightly packed. Enough for a long day out without stops, except for extra fluids. Given there is a fair bit of weight in all that, I imagine it exerts quite a bit of leverage at the mount position on the seat post, particularly if you hit a bump at speed. The direction of that leverage is almost at right angles to the direction the post is designed to take pressure, so if it says don't use with carbon fibre, I wouldn't try it.

a carbon seatpost shouldn’t be significantly weaker than an alloy one especially since it can accommodate the weight of a cyclist.

While I don't know much about how carbon fibre handles such stresses, I suspect it's all about what happens if it does break. Carbon is more likely to shatter with sharp splinters. Alloy would probably buckle. I know which I'd rather be above when this happens

CramCycle

I have the Carradice Camper longflap myself which is to bit for all I need but its light, easy to attach and always gets a comment in the style department (I know you think they are old fashioned in looks) and whenever I want to go further, I know there is that extra space. The support you mentioned is pricey and if you could make one yourself that would be great but some sort of support is a necessity as the swinging is apparently annoying for many (I always had a support but I can imagine). Also they aren't actually as big looks wise as you'd expect, fitting nicely behind with very little view of it from the front when your on it.

I seen an altura arran ( I think) on MayoGirls bike and that looked pretty good as well.

coolbeans

Forget clamping onto a carbon fibre seat post as it'll just end in tears. While CF may be strong it doesn't respond at all well to the compression stresses that the first few bags you've listed would subject it to.

blorg

Dr_Colossus wrote: »

most of the pictures I've seen of Audax riders usually carry some sort of additional bag.

There is a lot of tradition in audax where riders do something just because everyone else does it.

Personally I go up to 300km with just the jersey pockets and a small saddlebag with tubes, multitool etc. 325km is the most I have ever done in one day. For situations where the weather may be extremely changeable I use a small bar bag that will take a warm jacket. This is only really necessary for rides where it might go from 25C to snowing (it does do this in the Alps/Pyrenees in autumn) or extremely long rides in winter (300km+) For multi-day rides of 800-1,000km I have used an in-Sy bag that attaches to the saddle. I have used this with a carbon post incidentally. Doesn't clamp the post, all the hardware goes on the saddle rails. As a result of this max realistic weight is 3.5kg, anything above and it gets very wobbly. If you wanted to carry more I would look at something that clamped to the seatpost and changing your post (alloy seatposts are not exactly expensive.) But I wouldn't carry more than this anyway I don't think unless you are going extended touring.

rughdh

blorg wrote: »

...

Personally I go up to 300km with just the jersey pockets and a small saddlebag with tubes, multitool etc.

...

I did my first few 300k cycles with nothing more than a small saddle bag and just stuffed everything else into my pockets. For a 400 and above, I personally would definitely bring a bag. Faster riders might get away with it, in the summer months, in particular. Now that I'm used to the Carradice barley which I use with the bagman, incidentally, I wouldn't be without it.

Dr_Colossus

petethedrummer wrote: »

I have one of these, you are welcome to borrow it and try it out, if you're in Dublin. PM me if you want it.

I suspect it would be too big for an audax. You could carry a full change of gear in it easily.

Thanks for the offer Pete, yea I reckon it might be a bit on the large side and I'd still have the problem of clamping it to a carbon seatpost so I'll leave it for now until I figure out what's best.

coolbeans wrote: »

Forget clamping onto a carbon fibre seat post as it'll just end in tears. While CF may be strong it doesn't respond at all well to the compression stresses that the first few bags you've listed would subject it to.

Fair point and makes sense. In saying that though the seatpost already undergoes compression stresses with the seat clamp but it does have a larger contact area with the seat clamp and seat tube.

Many thanks for all your replies and help, I think for now I'm going to hold off and manage with the saddle bag and jersey pockets and maybe keep an eye out for an alloy seat post and then get something like the Altura Aero. Once I actually start doing longer cycles I'll have a better idea of what if anything is required.

Thanks again