See also also bike pic for other bike-related technical discussions and more about poor designs and failed parts.


Carradice Bagman Problems

Carradice makes bicycle "saddle bags" that are designed to attach to loops on the saddle and to the seatpost. Riders report several common problems using the bags:

Carradice Bagman Failures

To address these problems, Carradice sells "Bagman" racks. Pre-2009 Bagman users report "loose setscrew" problems, and some users report "failed quick-release" problems.

Failed Setscrew

Briefly, the Bagman supports the bag with a metal frame. The frame is held in the seat rail clamp using setscrews, but the frame is prone to "creep" out and leave the bag dragging on the tire. In addition, older racks use setscerws without locknuts and the setscrews are prone to come loose. Also, the setscrews are prone to break when tightened.

It appears some 2009 Bagman racks solve these problems, while other 2009 racks do not, see below.

In more detail, the metal frame has flats milled at the ends, and they slide through holes in the seat rail clamp and are held with setscrews. The clamp holes are short, and the metal frame is long so has quite a bit of leverage. As a result, the frame wants to move in the holes. And, as Jobst Brandt likes to say, "In the real world, everything is made of rubber." So even when the setscrews are initially tight, under load the metal frame can gradually "creep" out of the rail clamp, allowing the bag to drag on the tire. Note this is not simply loose setscrews: models with locknuts still have problems with the metal frame coming out.

Indentations in metal frame showing "creep"; also 8.8 grade Allen-head screws to replace setscrews.

frame creep; new setscrews

An "obvious" approach is to tighten the setscrews which hold the metal frame. Unfortunately, the setscrews seem prone to break. In at least one case, the setscrew broke off roughly flush with the rail clamp, making field repairs impractical.

An alternative is to remove the setscrews and replace them with Allen-head bolts of good grade. The thread is the same as is used for common water bottle bolts. Setscrews of a good grade should work, but high-grade Allen-head bolts are commonly available in U.S. hardware stores. Allen-head bolts make the rail clamp slightly wider, but the clamp is far enough back that few riders should have leg interference.

Failed Quick-Release

A second problem is the quick-release "handle" to release the bag. The handle is a short piece of rod, threaded at one end to screw in to the pin that supports the bag. Unfortunately, the handle sometimes unscrews. Once that happens, the pin that supports the bag will eject out the end of the bracket, causing the bag to fall out.

Quick-release "handle" unscrews, spring-loaded support pin ejects, leaving bag unsupported.

It is unclear if the handle is held by LocTite™ or a similar thread lock, but it might be a good idea to apply some preventatively.

As of 2011/01, it appears that replacement parts are not available, requiring either purchase of a new rack, or some kind of home-made repair.

2009 QR Bagman

It appears the 2009 quick-release Bagman solves the setscrew loosening problem by eliminating the bolt and using a pressed-in pin, possibly a roll pin.

From http://peterwhitecycles.com/saddlebag_support.asp as of 2009/07:

The new QR version eliminates a few screws that in the past could work their way loose. These new Bagmen should require less fussing about.

2009 QR rack

Oddly, it apepars the 2009 non-QR version continues to use setscrews.

The 2009 design probably solves the setscrew loosening problem, though if the pin is too large it will weaken the metal frame, and if the pin is too small it will be weak and the pin will fail. Using a pin instead of a bolt eliminates a clamping force, and it is possible the metal frame will move more in the rail clamp and gradually wear it away, eventually leading to failure. So if the frame starts to get loose in the clamp, it may indicate a pending failure.

Carradice Bag Position

Carradice bags work quite well for some riders, and compared to panniers they have less air drag and position the weight farther forward.

That said, two common complaints are the bag rubbing on the rider's legs or on the tire. The following picture shows bags mounted conventionally.

From http://www.wallbike.com/carradice/camper.html as of 2009/07:

Camper Longflap on silver bike, Super C on blue bike.

These bags are mounted on 62cm bikes.

two bags side-by-side

Note the bags hang forward, which is what can lead to interference with the back of the rider's leg. Note also these are on tall frames, yet there is only a few cm between the bottom of the bag and the tire.

Riders whose seat is far forward are more likely to clear the bag. With the seat back, leg interference is more likely. A common strategy is to add a spacer to the seatpost strap to push the bag back. However, doing so also makes the bag swing down and at the same time pushes it back towards the high point on the tire. Together, these tend to make tire rub worse.

Classic English cycles often have a durable fender attached, so resting the bag on the fender provides support and avoids tire rub. However, modern use typically avoids fenders and/or uses plastic or lightweight aluminum fenders, which are more likely to fail if a bag rests on them.

For smaller riders, Carradice makes some models in "low" sizes that are smaller around but wider. This is a reasonable solution but limits bag choices, and larger capacity "low" sizes push them out in to the air stream, increasing drag.

It seems another approach is a center strap that limits the drop right at the tire, tending to push bulkier items to the sides. Maybe this does not work as well as it seems, but for riders with tire rub problems it might be worth trying, for example a Fastex™-style buckle and nylon webbing.

Carradice SQR

Carradice also offers a seatpost-mounted quick-relase mount called "SQR". It is mounted on the seatpost, so it avoids the need for loops on the saddle and does not require space on the saddle rails to mount a Bagman rack. It also holds the bag higher and farther back than bag loops or the Bagman, reducing both leg rubbing and tire rubbing. The SQR nominally weighs 420g compared to 448g for the Bagman QR expedition.

From http://carradice.co.uk/mountain-bike-bags/sqr-system.shtml as of 2009/07:

SQR holding standard Carradice bag

Unfortunately, the SQR requires substantial vertical clearance to attach and remove the bag: to remove the bag, it needs to be lifted, rocked back, then dropped. Thus, it may not work on bikes with limited seatpost or a rear rack, even when there is otherwise ample vertical clearance.

Also, on bikes where the saddle is far back in the seatpost rail clamps, there is still leg/bag interference with some bags.

The following shows an SQR that is integral with an SQR Trax, in the process of being removed. The SQR frame is released from the upper SQR slot; the next step is to slide the whole bag down about 3cm, but note the lower edge of the bag is already resting on the rack. Even without a rear rack, there would be interference with the frame and fender if the block needed to be mounted lower due to less exposed seatpost.

SQR Trax and rack interference

It seems two changes would make the SQR useful for more riders:


Bag Loops

An alternative to the upper part of the Bagman QR is some kind of loop that clamps on the saddle rails. Although less convenient, for some uses they may be better than a Bagman.

[X]
ViVa bag loops, from http://www.velo-orange.com/vivabagloops.html as of 2009/08.
A washer under the screw head and a washer between the layers of wire may avoid spreading under load.
[X]
Cyclo bag loops, from http://www.sjscycles.co.uk/product-Cyclo-Carradice-Cyclo-Bag-Loops--Chrome-16431.htm as of 2009/08.

Riders may wish to replace phillips-head screws with allen-head (hex socket) or Torx™ for compatability with carry-along tools. Check also the nuts are compatible with carry-along wrenches.

ViVa Seatpost-Mount Saddlebag Support

Clamps to the seatpost and supports the bag similar to a Bagman or frame-mounted rack.

[ViVa Saddle Bag Support]  
This [...] bag support [...] clamps to your seat post, yet does not require seat post removal to install.

From http://velo-orange.com/visabagsu.html as of 2009/09

Carradice Seat-Stay Rack

Another approach for bag support is this Carradice rack. Listed weight is 150 g.

Carradice Seat-Stay Rack
From http://carradice.co.uk/racks-and-attachments/saddlebag-support.shtml
as of 2008/08.

Midlands Seat-Stay Rack

Another approach for bag support is this Midlands rack. It is presumably bent at its base at about the angle of the stays so it makes a horizontal platform. Listed weight is "under six ounces", or, presumably, under 180 g.

Midlands Seat-Stay Rack
From http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=290109773469 as of 2009/08

bag support MIDLANDS chrome vintage seat-stay England
clamps to seat stays
NOS = new old stock

  • as pictured
  • still in package, weighs under 6 ounces
  • will support a large bag such as Carradice or Karrimore!

Petersen/Park Seatstay Bag Support

Grant Petersen briefly sold thse bag supports, inspired by an earlier design from Park. They tend to bounce off if there is no bag load holding them down. About 250 grams.

[Petersen Saddlebag Support]   [Petersen Saddlebag Support]  

As of 2011/03/27, the same or similar rack is available from Grant Petersen at Rivendell, under the name http://www.rivbike.com/products/show/silver-hupe/20-136.

Quick-Fit Saddlebag Fitment

John Forester made these supports for a while, sold through his "Custom Cycle Fitments" (archived catalog at cyclofiend.com). Unfortunately, the "hook" around the saddle rails tends to bend open. About 140 grams.

[Forester/Custom Cycle Fitments Quick-Fit Saddlebag Fitment]   [Forester/Custom Cycle Fitments Quick-Fit Saddlebag Fitment]  

A similar "lift" version was made for low saddles and/or tall bags. The basic design is similar but the "lift" extension is longer, bent to keep from reaching back too far, and the arms are reinforced to withstand the extra leverage. Some pictures here.

Cyqlist One-off Custom

Clamps to the saddle rails. Wood blocks are relatively light and easy to shape, while aluminum bracket helps keep the wood integrity and supports bending loads. Wood blocks appear to be plywood.

[cyqlist-custom.jpg]  
Homemade adapter to mount saddlebag on Selle Italia Turbo saddle.

From http://www.flickr.com/photos/7289267@N06/3075411981/in/photostream as of 2011/03

Note recessed flat-head screws avoids rubbing on the bag, as do shaped edges near the bottom.

Durability would probably be improved by using as much radius as possible at "T", to sideways "arms", and weight would probably be reduced (thouch construction effort increased) by using as thick stock as possible then removing a center slot.

Carradice SQR Trax

Another choice is an altogether different bag. The Carradice SQR Trax bag is made of silicone-treated polyester. Like fabrics are used widely for their waterproofness, so a buyer might mistakenly conclude the bag is waterproof. However, it is water-permeable, even without being immersed, because the seams are not sealed.

SQR Trax and rack interference

Also, the web site (http://carradice.co.uk/mountain-bike-bags/sqr-trax.shtml as of 2009/07) lists a carrying capacity of 16 litres. However the capacity inside the bag, as measured by filling it with water, is about 12.5 litres, even with the internal "cuff" fully extended. Presumably the "other" 3.5 litres is in the mesh side pockets, but as they do not have a positive closure and are not protected from weather, they are unsuited for much general carrying.

Neither of these is "fatal", but the product literature is arguably unclear, and buyers who need a given level of waterproofness or capacity should be aware.