Perfect weather for a bike ride . . .

November 23, 2014

Front Bag Testimony: fork rake & trail, headlight brackets, and sepia tone


  For the first time in almost a decade, the Kogs gets something of a make-over - at least as far as the front end is concerned.  I've been sitting on a GB25 handlebar (front) bag for a while now, and I finally decided to give mounting it a shot.  Why the hesitation?  Well, that's me thinking too much - as is often the case.  I'm not the milli-metric nut-job I once was - but, I still appreciate precision and bespoke touches.  Centering and accuracy are simply part of the landscape here, so the activity remains therapeutically perfect for me... but, for a while I struggled with changing anything at all.  All I knew was, after almost a year riding with them, that bags mounted directly to the handlebars wasn't quite cutting the mustard.

SO, let's begin;  I don't have much footage of fabbing-up the front rack and decaleur setup, unfortunately.  During the build, it completely slipped my mind!  I will, later, post some photos to social media with some of the finer touches.  It's sloppy, not exactly straight, and uses P-clamps to hold it onto the front fork legs.

(holy SPIT-TAKE... what??!  Dude, NO!

Yes, clamps.  I despise clamps.  They have their purpose, but, it was always a difficult pill to swallow, me using them as a major contributor to
the bike.  I have proffered against clamps for ages - which is odd since I love zip-ties so much.  In my opinion, the use of clamps suggests immediately that I'm undertaking something for which my bicycle wasn't intended.  Curmudgeon to the core, me.  Therein lain the opposition.  (brushing up on my conjugations - though, I realize the use of lain here may be incorrect)  I had been waiting on myself to get the bike completely torn-down, sandblasted and refinished; and, parallel to that activity, having a new front fork constructed, OR at the very least having mid-fork rack braze-ons added to the existing fork to eliminate the need for clamps and their accompanying challenges.  To date, my Kogs Model P is likely one of the few remaining in use that has not been refinished.  Even the designer/founder hinted to the softness of the stock paint - but, I've never had occasion, the cash, or the reason to have a refinish done.

  The fork, however, remains the most troubling part of the equation.  I know I think too much - but, for the same reasons I won't use Rivnuts (a cold, blind-rivetted drill-your-own-rack-mount add-on) for this purpose, the thought of taking a torch to a "mystery" blend variety of 4130 CrMo to tack some threaded eyelets in place seems equally ill-advised.  In the hands of a skilled brazer, I don't imagine the fork blades would know the difference...but, I worry about burning right through it or leaving it too brittle.  The clamps on the other hand, arguably, may add MORE undesired stress to the fork than "reheating" it would.  SO, since the fork has other interesting variations (dropouts set slightly one higher than the other, fixed by me ages ago), and it also (also arguably) having the "wrong" rake.. well, it makes more sense to pony-up the additional cash for a well-made and specific fork to replace it, if I'm to eventually do anything.  Heck, on the subject of good-money-after-bad - the cash in sum-total would better be directed to an entire custom bicycle.  Someday... but, as far as I am concerned, my individual riding style and equipment preferences are yielding the reasons typical of someone finally ready to commission a builder for their next frame, rather than an off-the-peg bike.  Its been a long time coming.

SO, yes - clamps.  With the rack fitted, however, the real issue began to surround the headlight bracket.  Ever since day-one, way back in April of 2002, I'd been using the fork-crown mounted headlight brackets supplied by Peter White Cycles to mount my headlights.  They've never set a foot in error; so, another bitter pill.  If it isn't broken... rolled through my head over and over as I disassembled the beautifully simple (and centered) headlight bracket.  The up-side here involved removing an undesirable interface from the front brake, so I suppose that's good.  Still, how to get it onto the front rack?  While SOME brackets are available for purchase, I was equally frustrated by their high cost and their faulty designs.  Over the course of a month I had examined and mocked-up no less than ten different solutions to this issue, before finally settling on something found at Ocean Air Cycle's webpage.  Once I had the image of a partial chainring radius peeking out from under the front bag in my head, I was in the garage looking through my pile-o-'rings to find the right one.  The photos can do most of the talking here:


Sparks fly as the chainwheel gets upcycled... maybe "laterally-cycled" is the right term here?  Dremel heavy-duty cut-off wheel on the Dremel's cable-driven "wand."  This method is handy and "low sweat", but really no faster than a hacksaw and a good file.  Use what you have, but never be limited by what you don't.

Steel, 74mm bolt circle... (or 94?, whatever.)  26t chainring yields two brackets of different lengths, or matched twins.  It's a shame, the amount of leftover scrap - but, I saved them for either genuine recycling, or something artsy.  The three-hole version you see was eventually shortened to two-holes, as shown in the final mount below

The finished product:  the final mounting required a trip to my favorite hardware store for a couple hours of rummage through my favorite part of hardware stores in general:  the loose hardware bins.  The set-up you see consists of the two brackets, a nylon spacer to match the width of the headlight's mounting tab, a knurled spacer upcycled from an old front brake to space the assembly out and away from the rack a bit, a 25mm M5 Allen-head bolt, two M5 oversized washers, and a Nylock nut for mounting to the rack.  Additionally, for the light, a 20mm M6 Allen-head bolt, two M6 washers and a 6mm Nylock nut.  The wires, unlike on the Ocean Air example, are protected between the two chainring mounts and then transition to the rack, and onward to the hub and taillight, respectively.  So far, the set-up is proving to be rock-solid.  It's sure to start a conversation or two at the next control!

The headlight brackets become paired-up to completely eliminate headlight beam vibrations.  The light, as a result, gets the same even clamping pressure on both sides of the mounting tab, as its design requests.  It's below the bag, but, high enough next to the tire to nearly eliminate distracting beam shadows.  Most importantly, it can be seen from either side of the bike at all times when viewed by on-coming or cross-street traffic.



The mid-life crisis style randonneuring front-bag, ala Gilles Berthoud.  The level of construction is - as Jan Heine put it - "unimprovable."  That's pretty darn close to reality, but, I have yet to meet a cycling product that I didn't want to modify or "improve" in at least three ways prior to installing it.  This was no exception - but, I just can't do it.  It's too pretty.



Everything seems to fade into sepia tone whenever I look at the bicycle now.  Decidedly old-school, but, timelessly functional and appropriate.  I do, however, have a strange desire to buy a lot more comfortable and loose-fitting cycling attire, preferably in tweed or plaid.


The front bag itself?  Again, unimprovable.  It's great, everything I'd expected - if not still a bit floppy, which I'll eventually remedy once the right solution pops into my head - and I've already mocked-up about seven possibilities there, to date.  

Riding with the bag?  Well, that's where things get interesting, and where - as the title suggests - we get into rake and trail.  What the heck does that mean?  I'll tell you this much, do not Google it unless you are the sort of person that can remain unaffected by such discussions.  If you take a wrench to everything the moment someone in a forum declares your solution/bike/bag/tire/chain-lube "ridiculous and/or downright dangerous," like I used to, don't read about rake and trail.  You'll go nuts.  It's taken a LOT of willpower to forget my first reaction to a few of the things I'd read, which rhetorically presented itself to me as:  "re-raking a front fork... how hard can THAT be?"

   "This is sorta the same as a Var fork-rake jig, right?" he said, holding the decades-old hunk of steel pipe known collectively as the shop's "cheater bar."     

Dude.... no!

The solution?  When it comes to rake and trail regarding front forks on bicycles, I say "yes!"  Both are highly recommended, and you really shouldn't ride a bike that doesn't have some amount of rake/trail to it.  There.  Filed carefully alongside "chain-lube", "politics", "nutrition / Cytomax", "tires", "religion" and "what constitutes "assistance?" between controls", under the heading "things never to discuss in an online cycling forum." 

Simply put, "trail" as it's related to forks is the distance between the exact point where the front tire contacts the road when a line is drawn perpendicular to the ground and passes directly through the center of the front axle, and the center of the bicycle's steering axis, which is the center-line of the frame's steer tube.  As you extend each line to the ground, the two lines will cross, and as a result the point where the tire hits the road will trail behind the steering axis.  It is precisely this which can affect bicycle handling and stability perhaps more than any other dimension across a bicycle's geometry. 

Fork "rake" is simpler to understand.. and it's the linear distance between the steering axis of the front fork and where the center-line of the front axle is held.  It's sometimes referred to as fork offset, as-in offset from a fork with no rake at all.  

Now, you can look online for exhaustive details and discussion on rake, trail, wheel flop, load-handling, understeer, oversteer, stability vs. trail vs. forward speed, etc.  It is, truly, fascinating material if you are interested in WHY bicycles are made certain ways, and what makes one bike better at "Z" than another, and conversely.  It's a big subject regarding the addition of front loads on road bikes;, but it applies to all bicycles:  imagine a mountain bike race with long, fast downhills, steep climbs, and tight, technical turns!  It becomes really vital to understand rake and trail if you're to build a bike that can handle all of these things well - all while compensating for the undulations of a suspension fork.  Anyone interested in framebuilding should read up on this.  

...but this is about road bikes.

Now, the notion is this:  most mass-produced bicycles available today have a "high trail", but, this would assume comparison to something neutral... which isn't largely agreed-upon.  That's when discussions heat up.  Neutral handling is something a general-purpose bike should likely aim for:  stable at nearly every speed, can handle a front or a rear load... but, you'll feel the differences and will have to adjust your riding, cornering, and climbing style to compensate.  

Specific to the discussion on front-mounted rando-style bags on small front racks, some will try to convince others that running such a load up front on a bicycle with the "wrong" trail will result in an instant trip to the ER.  Most of the information I've gleaned, however, comes from a myriad of sources on the web where I'd found sensationalism removed from the discussion.  Names like Heine, Moulton, Meade, Wetmore, are among those I'd like to thank for their assistance in understanding this most intriguing facet of bicycle-related science.

Ok.. so, YMMV, but, this is my impression:
I've only the bike I have... and there remains little I could easily do to modify its geometry to benefit one thing over another.  Since I have no concept, on my bike, of what should feel like what... well, there you have it.  I only have my impressions of how it handles loads, front, rear, or un-loaded.  I admit, when I'd originally read the outline of why the Kogswell Model P was for me, the point about it having "been designed around/to use the Panaracer Pasela 700x28mm tire" didn't even resonate.  I thought to myself... "yeah... whatever."  I happened to run those tires ANYways, so it didn't matter to me WHY the designer felt compelled to mention it.  

So, a little deeper we go:  the TIRE you choose does have an effect on frame geometry.  Since we are concerned with the point where the TIRE contacts the road directly under the front axle in relation to the fork's static steering axis (which is dictated by the angle of the headtube), it stands that mounting a taller tire will directly increase trail.  The rake will remain unchanged, as will the steering axis - but, the difference between a 700x20mm event tire versus a 700x40mm all-surface tire will be noticeable.  So, if a builder is after a certain set-up (like a bicycle made for heavy front loads or cargo vs. a all-out time-trial bike vs. an all-rounder) they will likely be aiming for a specific trail number.  To do that, they need to decide what tire they'll use.  There you go.  If you can plug in the tire variable before the frame takes shape while knowing what you want to do with that bicycle when it's finished, then you can adjust the head angle, fork rake and other dimensions to complement it.

Where *I* used to get hung up -- and something which may hold true for many cyclists -- is that it was ONLY the tire which I felt made things feel different.  I would then, falsely, make proclamations about one tire being noticeably better than another, etc.  I wasn't ever wrong though, especially when discussing, say, one 23mm tire compared to another 23mm tire.  the fact I didn't know precisely WHY I preferred a larger tire over a smaller one also isn't really important.  What is important is that I found something I felt was comfortable, and made my decision based upon it.  It really shouldn't go much deeper than that for many riders.  But, it should be noted:  the reason forums often take the tone they do in the arena of tire discussion is related to SO MANY variables, including how that tire affects the bicycle's geometry, and there is almost no way to predict one cyclist's reaction over another's.  Is the reason someone's average speed went up 2mph really to the tire's credit, or, was it the reduction/increase in trail which yielded an improvement in handling and/or stability which helped the cyclist throw down a better lap time?  It really all depends, and there is a lot going on up there.

Plus, we're talking about millimeters here.  Quite literally.  There will be, for any given bicycle, a noticeable difference in bicycle behavior if you were able to sweep the fork back and forth over only a 2cm range, front-to-back.  Some folks in the forums can be read discussing differences on the level of 50mm of trail versus 47mm of trail.  I'm not certain I am enough in tune with my bicycle to feel that.  A BIG point of contention, however, remains in that human beings are remarkably adaptable animals.  Any sort of positive OR negative handling consequence from a slight change in trail would likely be compensated for and nullified within 10 miles of normal riding...so, does it matter?  YMMV.  Unless you are working with a custom bicycle framebuilder on a project RIGHT NOW, don't worry about it.  When you get to that point, however, you and your builder can work out any problems you'd like to solve, and see if adjusting rake and trail +/- neutral presents a solution.

Like anything else cycling-related, however, take all of this with a grain of salt, please!
If you like it, do it.  Don't let them, or me, talk you into or out of anything you are having success with.  Don't be afraid to play around with things, but don't do it because anyone told you that what you found that worked is somehow wrong.  To the credit of the authors I mentioned before, they all found a way to explain how rake and trail can affect certain things, but never did they posit that any one measurement or approach was wrong.  Simply, as an example, running a heavy front handlebar bag on a bike with high trail numbers may not be ideal, and it may feel twitchy or unstable... but, it may not feel that way to everyone.  Some will prefer that sort of feel, some will feel that it's "faster", others will be alarmed by it.  You can begin to imagine all the conversation this inspires.

For me?  I prepared to measure the Kogs for trail, and then quickly tossed out the idea.  I never took the tape measure to it, because I didn't need the mental thorns.  I can't do much about whatever number I was going to see, so my solution became simply mounting the front bag and going out for a ride.  I was immediately satiated.  The ride, if anything, feels more stable - not less - with the front bag mounted.  I did feel a smidgen of hesitation throwing the bike into a hard corner... but I betcha it was ME thinking, and not the handling.  

It's too late to be "short" here, but, my point involves the Kogswell still being the bike for me:  it can handle a front load on pavement and gravel and actually feels more stable as a result.  It has clearly handled rear-loading in the past with bike camping trips and commutes, and with the Carradice bag loaded up.  It will, no doubt, handle the 600km+ task of having both the front bag and the Carradice mounted up.  Sure, it won't handle like a crit machine, but it never did.  If the handling is affected adversely, in any of these cases, I've simply adjusted to it through the course of riding.  In summary, this - for me - is a non-issue.

The bag itself, and its placement, however, are important.  The bag is not very close to the handlebars, so I can use ALL the handlebar real-estate... which means I'm now more comfortable, or more able to affect my own comfort.  I can get to anything I need to.... not that I needed to before... without dismounting.  I can be better prepared for arrival at and departure from controls on brevets and permanents.  I can see the cue sheet, all the time.  I can see a photo of the wife and kids for inspiration, or my favorite quote, or a postcard.  I can listen to music without an earbud if I choose, because the phone is handy, and I can take fast photos for the same reason.  I can carry food, clothes, whatever.  I can still ride gravel -- because my initial test ride included about ten miles of it, and I often purposefully rode over the washboarding ruts to try and get the clamps or the rack itself to fail or at least move.  Neither happened.  I don't feel this need to fill the whole thing, as has nagged me in the past.  I can just ride.

That's all any of us should be doing, eh?


Did everyone receive theirs yet?  Worth reading, even if you "already know this stuff."


Now, I plan to curl up with the above and re-energize the little grey cells about long and longer-distance riding.  Ahhh...

Next up, something simple... and a chance to make it, err... simpler, and more-better?
The lowly bicycle bell... something, IMHO, every bicycle could benefit from.  This one is decidedly techy, is made in the USA, and looks good doing its job of being a bell.  I mean, you can't SAY much about a bell... but, I enjoyed finding this kickstarter-backed company, and if I've got a spare $40 laying about, I'll likely pick one up.  It's just better, that's all.  A well-made video, also.  One thing I *LOVE* about the video:  the founders highlight "race bikes" on equal footing with townies.  I like the idea of a cycling culture void of boundaries and taboos, racers with bells.  It's a good vibe.  The Spurcycle Bicycle Bell.


That's enough on this subject... off to ride!



2 comments:

Biker Bob said...

Good job on the headlight mount. I'm curious why you didn't grind/cut off the chainring teeth all the way, for a smooth curved appearance.

Keith G said...

Well, I'd considered it... I did grind the teeth down a little bit, just to prevent any mishaps, yet, I wanted to keep it looking like a chainring jsut for the effect and the nod to upcycling in general. It would indeed look a little sexier with nothing but a smooth, elegant curve... perhaps I'll save that for the next frame build