April 30, 2015

A home-brew saddlebag mount (for saddles without bag loops)

So, what does one do when one comes across a problem to which the solution may not be immediately apparent?  Let's find out. 

The problem:  After struggling with some post break-in saddle issues with my GB Aspin leather saddle (which has bag loops), I've moved back to a design which has suited me well in the past.  However, all this time, I had been making the mistaken assumption where sit-bone width equals the width of saddle I'd need.  Thusly, I had ridden well over a decade on my Selle Italia Flite Trans-Am.  It's a very well-made saddle, and to-date it remains in service on my son's bike.  However, at 143mm wide, the same width as my sit bones, it had begun to turn into something of an "ass hatchet", if you'll forgive the term. (Thanks, Noah! LOL)  This new saddle is wider, at 155mm, and supports me far better... and, bonus, it shouldn't change shape as drastically as leather.  Granted, leather saddles work for a lot of people - however - They just don't work for me.  I think "third times the charm" is diligence enough.  When these leather saddles do break in for me, the hammock effect simply places too much pressure on "the area."  As part of the break-in process for leather, however, when this does occur the rider simply adjusts the saddle to put the nose (first 1/3rd of saddle) level, raising the heel higher, and (hopefully) returning the rider's weight to the broken-in sit-bone area, and removing the hammock-created pressure.  For me, unfortunately, the adjustment created more pressure on my arms and shoulders - as I continued to slide forward, off the sit bones portion and onto the nose - which creates the aforementioned hatchet effect - while also placing my knees too far ahead of the pedal spindle.  Push backward with arms for half a pedal stroke, count out five to ten more pedal strokes, and repeat.  All in all, what this final leather saddle adjustment successfully does for most simply doesn't do anything good for me in practice.  The return to a "racy" saddle with a central cut-out, I can tell a huge difference.  The horrifying, shorts-ruining saddle sore received during the Oak Grove 300k is now gone, and my arms, neck and shoulders feel much more relaxed - I've returned to a neural position, and have a saddle which I can actually sit on.  YMMV.  I'm already eyeing the purchase of another one, just in case the Specialized line-up is to suffer the same marketing-driven change which discontinued my old Flite T/A.

...but, dude, you should have:  tensioned the saddle, waited longer, soaked it in baby tears, rubbed it with an ill-tempted sea otter, hot-dipped it in maple syrup, and then fine-tuned the angle over a period of months until it'd been just right.   Yeah.  Been there, done that; and, I'm already a sad example of poor choices and negative history repeating itself.  The less tweaking I need to do, the better off I am in the long run.  I'm not heading down that dark alley anymore.  The Specialized saddle, installed now and with already a few hundred miles logged, was comfortable right out of the gate, and hasn't changed a bit.  I'm not sliding, I'm not aching.  Leather is a fantastic product, and I love the way it looked on the Kogs, but, I refuse to suffer for the sake of vanity.  If something works, I'm using it - I don't care what it's made from.  Life is too short to continue wasting time on things that aren't improving my experiences.  Twenty-four months is plenty long enough - perhaps too long - to determine whether or not it was to eventually become comfortable.  Moving on.    

Saddle problem sorted out, the primary problem has created a secondary problem solved by the solution outlined in this post.  Since this is a new, "racy" saddle, it obviously doesn't have bag loops to allow the attachment of a saddlebag.  That's where we are today.

Now, filing this carefully under the "time is money" heading, I must preface ALL of this by informing you, the reader, of the existence of many products manufactured and sold to solve this particular issue.  Carradice makes their own saddlebag loop attachment for saddles, and a separate quick-release system that I've used in the past, which attaches to the seatpost.  Unfortunately, while their QR design allows easy release of the saddlebag, the seatpost mount left behind after bag removal prevents one from installing a regular wedge-style seatbag.  There are also fine examples from Nitto of Japan, and a few others by "Bagman" and some whose names I forget.  There are also many home-brew solutions outlined on the Bikehacks site, and on spurs off of Sheldon Brown's site.  For me, while it would have been cheaper to just buy one - if I consider the time I invested here - I enjoy fabricating, drilling, sanding, polishing, shaping.  It's almost therapeutic, and I see it as a way to hone certain skills which may someday lend themselves toward larger projects like racks; and, ultimately, complete bicycle frame-sets.  For now, it's a simple hunk of 6061 Al angle stock from the local hardware store.  $8.00, if that... and long enough to yield about ten of these "mounts".  So, while it did take time in my non-mass-production hands, the materials themselves are fairly cheap.  If I recall, for comparison, the Carradice clamp-on saddle rail bag loop solution is at least $24, and the Nitto is closer to $100.  Close examination of Nitto's workmanship, however, indicates the bargain their price represents for the aesthetically-minded.  Nitto doesn't do anything halfway, for sure, and the results are stunning and solid...  still, a little rich for my pocketbook, so... here we go:

Since moving to a front bag system, most rides don't prompt much more rear storage than provided by a typical wedge-style seat bag.  In fact, the 400km level is probably the dividing line - that ride can be done in under 24 hours, typically, and in moderate weather one doesn't usually need extra storage for bulky layers, or extra 'day two' clothing.  The majority of all bike sales are directed at folks who ride far less than this, especially the weight-conscious racing folks.  Saddle loops, then, simply don't make sense for most aftermarket saddles.  Even for randonneuring, my front bag gives me everything I need, but, jumps to 600km and beyond - just a bit more space may be desired.

Basic aluminum 90 degree angle stock - first cut to length, about 10cm, and edge polishing to avoid snags or saddle cutting edges.  The dowel rod underneath comes into action later on in the process.  This is accomplished with a hacksaw, a metal file, and some foam-core sanding blocks, which work well and keep the material removal very even and consistent, regardless of pressure.  I don't have anything fancy like a bench grinder - in fact, my drill-press is about as advanced as I get in my shop at the moment - and that drill is about 35 years old, and really needs to be retired as it tends to not remain centered, due to the bearings being quite loose.  All my cuts, holes, and finishing is effectively done by hand, the drill being the only power tool used.
Holes drilled in both surfaces after the edge finishing had been completed.  The larger relief openings (for weight savings... on a mount for a 10kg max load saddlebag. LOL) are created with step-up drilling from a pilot hole, and final drilling handled by a metal hole cutter - an invaluable bit, it creates perfect openings from 3/8" up to 1/2".  Two holes are opened with this bit, and then the space between them cleared with a small coping saw to create a single, oval opening.  
The smaller holes drilled provide perfect anchoring of the work against a hunk of 2x4" wood, allowing a lot more flexibility when working.  The 2x4 is clamped into a bench vise, so both hands are free to work.  On the left, one of the oval openings has been cleaned up and finished with emery cloth strips, to round off all the edges and even the openings with their perpendicular surfaces.  At right, the extra material has been sawed out, but it has yet to be filed and finished.  On the surface butted up against the wood, the two drilled holes haven't had the excess center material removed yet.

I could polish and radius edges and corners forever until it'd be "perfect" - I invoke Wabi-Sabi on that front: perfection is not my goal here.  Moreover, that's why the $24 for a manufactured product suddenly seems "cheap" when considered against the weeks of sporadic start/stop/revisit cycles by which this project unfolded.  Now, as good as necessary; it awaits the next steps.  Metal-work, complete!

...fine, maybe a little more polishing with the super-fine sanding block, to get the beginnings of a mirror-like finish.  I'm perhaps most proud of the singular line I've created from oval to oval, where each edge on each of the two planes sort-of intersect.  Yes, I've had more than a few comments likening this to a door strike plate for a deadbolt - and I got a good chuckle out of that once I realized it also - but, the rest will make sense in the coming images.

Now, the dowel rod comes into play.  First, an arc of material is removed to create a flat plane from about a 1/5th of the rod's diameter.  This will allow it to sit flush against the aluminum backbone.  The pencil marks are addressed in the next step.

Now, 180 degrees from the flat area, a wood rasp is used to notch out three 1/4" wide slots, the purpose for which is found in the next step.

Now, the saddlebag mount begins to come together, the final steps involving high-tensile (75 lb.) zip-ties.  For visual purposes here, neon multi-colored ties are used.  Three of them pass through the aluminium backbone, one for each pair of holes drilled through the "two oval" plane.  These line up with the notches carved in the previous step, which will prevent the dowel rod from creeping side to side once affixed.

With the zip-tie heads tucked against the flat, inner surface of the backbone, each are tightened around the dowel rod until no movement remains.  Wood against aluminium can create a bit of a "creaking" effect, which I discovered in the first field test.  This is mitigated with the addition of rubber washers - a total of six - each passed over the zip-ties and separating the wood and aluminum surfaces.  This, via rubber compression, allows a bit tighter cinch on each zip-tie for a very secure final fit.  This completely silenced any "creaking".  
An underside view, showing the zip-ties seated in the dowel rod notches, and cinched up against the rubber washers.  While these washers can be had at any hardware store with those handy parts bin (usually my favorite section of the store), I opted to save a little cash and instead bought about two feet of good ole automotive vacuum line.  Using a good razor and a small miter block I am able to spec washers in whatever thickness I like - hundreds of them.  In addition to being applied here, I've used the same material on the decaleur for my front bag.  This completes the portion from which the saddlebag itself will attach.

Try to ignore the occasional switch back and forth between yellow and pink zip-ties here, as the photos had been taken out of sequence between field tests three and four.  the concept is effectively the same - here, the remaining plane is comprised of one larger oval and two pairs of smaller holes through which the last two zip-ties pass.  This is the section that will attach the assembly to the underside of the bike saddle.

Missing from the shots with the yellow zip-ties are the addition of spacers/pads/silencers which will fill the space between the saddle rails and the aluminum backbone.  These are rendered from the same automotive vacuum hose.  A longer length is cut from the hose, and then slits are created though-which the zip-ties are passed.  This creates a thicker, more compressible cushion between the rails and backbone, which serves to allow tighter zip-tie tension, and adds a tiny bit of suspension for the saddlebag itself when under load.  Further, this holds the rubber itself captive, so, upon removal, you don't lose track of them when the next install comes around.  This also adds just enough spacing to prevent the dowel rod from being cinched too tightly against the underside of the saddle itself, which could create interference issues for the rider as the bag would be brought too close to the back of the cyclist's thighs.

Here, with the saddle added to the shot, the entire concept takes shape.  The remaining two zip-ties (they changed back to yellow again!) loop around the saddle rails, and then are cinched from underneath - you can see the zip-tie heads just on the other side of the oval cutouts.  

Finally, with the saddlebag added to the mix, the final design should be apparent.  Final closure and trimming of the ends of the saddle-rail zip-ties is all that remains to perform.  The leather straps of the saddlebag loop around the exposed ends of the dowel rod.  Simplicity might suggest one remove the dowel from the design completely, yet, in an earlier, wider prototype, this created a lot of bag-to-rider interference while pedaling, as the bag is pulled too high and forward under the saddle.  Considering that saddles with bag loops typically have those loops under the rearmost edge of the saddle, to prevent this interference, the dowel rod in this design achieves the closest match to where the bag should be - albeit still a bit forward of "ideal."  Further, the dowel rod's radius places less wear against the bag's leather straps, and the natural flexibility of the wood adds a tiny bit of additional suspension, in addition to what the wooden dowel inside the bag itself provides, as part of the Carradice design.  The true test will come on an extended ride, to determine if the mount tends to creep at all, or similar.  In the future, I can envision a metal-only version made from larger angle stock, which would place the bag loops exactly where they should be - but, if this works out, why mess?  the colored zip-ties add an interesting flair - but, may be replaced by standard black once deployed on brevet.

I'll report back after a few long rides with findings and notes, if any - yet, I don't anticipate issues at this writing.  I'm still taking a few extra zip-ties along, just in case.  ;)
And, yes - a lot of this could be solved by simply doing as most Americans do:  use a rack trunk.  Well, the rack I'm using is very narrow compared to most - and in addition to not being able to find a rack trunk that fits it correctly without me having to add some sort of platform, I feel they place too much weight out behind the rider, which can feel weird when climbing out of the saddle.  The English, transverse-mounted saddlebag solves this (for me), and heck - it's already paid for, so... yeah.  

So, there you have it --- the market doesn't really demand too much of this sorta thing, and while products are easily ordered which accomplish this, I just enjoy the process of taking an idea from brain, to bench.  If nothing else, it creates unique conversation pieces when attending local rides, and gives that personal touch so important to one's randonneuring machine.  

...now, time to go ride! 
Hopefully up next, the Oak Grove 300k report... and hopefully before the 400k unfolds THIS weekend.  Ack!  

Thanks for reading!


e0richt said...

couldnt you have taken the dowel, filed a groove for the zip ties (in order to be able to center the dowel to the seat) and zip tied the dowel directly to the seat?

kG said...

Quite right, it certainly would have worked fine and would have involved a LOT less labor; but, at least in my case, the saddle itself is quite thin (top-to-bottom) and the dowel and saddlebag ended up being too close to my backside while seated, especially while climbing or sitting up. The addition of the aluminum bracket provided enough of a standoff to eliminate that comfort issue... although, honestly, losing a few pounds from the rider would have helped, too. HAHA From a design perspective, however, using ONLY the dowel would be far more stable and have fewer failure points, for sure. On saddles with more padding, or more of a turned-down rear edge, the dowel would be farther from the rider and likely eliminate this issue entirely. There are so many good hacks out there, however, this definitely is not the only way to fly. Thanks for your feedback!