Category Archives: technical

Shimano 11s Mechanical Front Changer on a Calfee

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Whew!  Yeah… it’s been a while.  I write this from a train, because it’s one of the few chances I’ve had to settle down enough to focus on it.  I figure however it’s about time to relay an experience I had building up a Calfee Luna last season, an issue actually, and the solution to which I arrived.  Some time ago I’d heard of difficulties getting Shimano’s 11-speed Ultegra front derailleur to work optimally, and didn’t quite understand what the problem was.  It’s just another derailleur, right?  Now that I’ve seen it myself, and not heard of a solution, I find it hard to believe others aren’t occasionally encountering this, so here’s a description of what worked for me.

It’s no secret among those who know me that I have minimal enthusiasm for these component manufacturers each time they release another group with more gears.  I was fine with 5 and 6-speed, and really liked 7-speed.  When they released 8-speed that would have been okay, but 7 was enough, and the 8-speed system never seemed to perform well.  I’d rather have 7 that work great.  9-speed was fabulous, in my opinion.  It shifted well, was serviceable, highly compatible with off-road components – allowing us to develop creative gearing solutions for tandems and touring bikes.  It was also the first time we saw truly wide ranges available for folks who needed them with minimal compromise to shifting performance.  Then they jumped to 10-speed… yawn.  The groups got noticeably lighter and stiffer, but the tenth gear didn’t matter much and performance became finicky and less reliable again, and the superior features did not require an additional cog.

Eleven speed appears to be a whole different story.  Historically I wouldn’t have cared about that 11th gear, if you can’t tell by now, but properly installed this stuff works brilliantly.  The range for a double is wider than the old triples, and the ease, crispness, and response of shifting feel is phenomenal.  Even any lack of cross-compatibility (road vs. mountain) is beginning to not matter any longer.  The price for this however, aside from monetary cost, is the precision required to get it set up working perfectly.  This brings us to the point of today’s post.

Calfee's asymmetric bottom bracket shell

Calfee’s asymmetric bottom bracket shell

After so many years of building bikes using frames from Calfee Design, I had somehow forgotten Calfee build their frames using asymmetric bottom bracket shells.  I’ve never seen a mis-aligned Calfee frame, but you can clearly see in the photo that neither the seat-tube nor the down-tube intersect the shell at its center.  This is intentional, and perfectly okay as long as the bottom bracket, the wheels, the steering axis, and the saddle’s center are all within the same plane.  That is to say the frame must be in alignment, and it is, even though the shell is offset to starboard.

If you understand kinematics you will recognize that the attachment lever and parallelogram on a derailleur have different relative movements throughout their stroke.  Although the parallelogram ensures the cage’s stability and vertical orientation, it does move through an arc.  Since it’s activated by a cable pulling on a lever, and this cable pulls in an effectively linear fashion (as opposed to unwrapping about a barrel), a given amount of cable pulled at the lever will result in different resulting movement at the cage according to location within its range of travel.  Manufacturers account for this by matching the radius of the control’s cable wrapping mechanism to the dimensions of the contact points and parallelogram in the derailleur.  SRAM in particular, I believe, takes pride in their 1:1 pull-to-response ratio.  That’s cool… but one of the sweetest things about Shimano’s latest 11-speed mechanical system is the fast, smooth, and effortless action of the front mechanism.  This is acheived using a much longer lever than in the past, even requiring variable cable anchoring.  As brilliantly as it works, properly adjusted, it is unfortunately rather unforgiving to even minor variations in spacing from the seat-tube.

I found on several initial builds that the setup required a bit extra care in getting the adjustment perfect, and there’s the new trim “feature” which disallows the derailleur from slamming all the way to it’s lowest point upon the down-shift, but the results were in general excellent.  Trying to finish the build on this Calfee however, no matter what I tried for yaw alignment, cable tension, and limit screw settings, it was simply impossible to get full swing out of the derailleur and it would rub the chain on the big ring.  By the time the cage had reached the big ring position, any further cable pull would result in the derailleur moving up more than out, because its mounting point (the seat-tube) was too far away.  What do do?

standard vs. wide spacing

SRAM’s standard vs. wide spacing clamp

One idea I had was an eccentric clamp spacer, permitting fine adjustment.  I still may work on further developing that for similar applications, but I then remembered SRAM makes a Wide Spacing version of their clamp adapter.  Their clamps are very light and well made, so far seem reliable, and integrate perfectly with SRAM’s own chain-watcher device – a rather clever design.  They are however made to support exactly the profile of SRAM’s own derailleur body, preventing flex and yaw movement.  Shimano’s derailleurs don’t rest well against the little tab protruding out from the clamp, so I filed it down to fit the contour, and installed.

Problem solved!  It works perfectly and has often become my clamp of choice for many builds other than just Calfee frames, and for non-SRAM mechanisms.  Plus we still get the added benefit of using SRAM’s fancy chain-watcher if needed.FD6800 topA couple final notes:

  • I must admit I do not remember what the initial clamp adapter was that I tried.  It was in all likelihood a Shimano, which I have otherwise found to work well.
  • I have installed every edition of Shimano’s Di2 front changers to Calfee frames, more times than I remember.  We never experienced this issue, so it appears to only apply in the case of 6800 mechanical.  That said, I am curious to explore whether front shifting performance might be further improved this way.
  • The FD-6800 uses a yaw-preventing set screw just like the Di2 mechanisms.  If the clamp is filed to fit well, this set screw becomes unnecessary.

Motorcycle Handling and Chassis Design: the art and science

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Foale, Tony
Spain. 2002.
ISBN 978-8493328610

When I first heard of this book, probably around the time it was published, I just… had to have it.  At the time it was challenging just to figure out how to get one.  Entirely self published and distributed from Spain, this treatise is arguably the most definitive writing on the hows and whys of handling in single-track vehicles.  As should be obvious from the title, it’s not about bicycles, but you don’t need a deep imagination to recognize how much can be learned about bicycle geometry from studying motorcycle dynamics.

Bicycles of course do appear in the text a couple times, and are used to experiment and clarify some of the physics principles governing steering and lean-angle.  We must however bear in mind an important point about the differences between motorcycles and bicycles with regard to analyzing their handling characteristics.  On both machines the rider is a critical element to be considered as part of the machine.  The motorcyclist however is a relatively small percentage of the machine’s (bike and rider) overall weight, often less than 35%, while of course a bicyclist comprises the vast majority of the machine’s weight, rarely less than 80% for adults.  Add to that the sheer differences in power, and these have profound effects on the vehicles’ centers-of-gravity, and how the rider manages the CoG.  Tony FoaleAnother distinction (of many) is wheel and tire size, weight, casing design, pressures, and forces.  Although mostly the same effects exist in the tires and wheels of both machines, the magnitudes of those forces are so vastly different that we must be very careful with any assumptions we make about their similarities.  In numerous instances a line of understanding, in terms of handling design, cannot be directly applied between the two vehicle types.  Nevertheless this book provides tremendous insight, at the very least, into the sorts of things a serious bicycle designer should be considering and trying to understand.

Motorcycle Handling and Chassis Design is one of my favorite books on my shelf, but I’d only recommend it to others who are also interested in the rather dry details of handling geometry in bikes.  The clarity in the writing, the comprehensive analyses, hundreds of photos, diagrams, and graphs, and the well thought out explanations are astounding.  Sure it reads a bit like a text book, but anyone would be hard-pressed to explore and report on such a technical topic more effectively.  The author‘s brilliant efforts to go light on mathematics, but instead illustrate with practical theory and experience, must not go unrecognized.

I understand a new edition was released in 2006.  I have not seen a Spanish version, but my paperback copy is entirely English, and written so well it’s difficult to imagine it having been translated.  The latest edition claims to be even better than mine.  Hmmm… What’s a book junkie to do?

tandem fitting

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Most folks familiar with us also know Diane and I have been an avid tandem team since 1998.  For many years, having first-hand expertise, we also fitted and built quite a number of tandem bikes for customers, including several very customized bikes.  Some of the more common early questions in selecting a tandem are about fitting, and whether the numbers on our singles are transferrable.  The super-short answer is a likely yes, but… it’s heavily qualified, and you probably know by now that short answers don’t come easily to me.  Having just fielded such a question, here are some thoughts about the basics:

This isn’t true for everyone but, for many of us, fitting a tandem is a bit different from how we like to ride our singles.

Generally the stoker wants to be a little more upright, because she (or he) can be, since she’s tucked out of the wind anyway, and usually wants a better view of passing scenery.  Additionally, as long as you’re confident the rear seat-tube will be a good length for her saddle height, knowing exact details of her final fit parameters is rarely critical ahead of time.  The rear of the bike is so highly adjustable that you should need little more than confidence that her parameters can be met once you have the actual bike in front of you.  Note too that (for most stokers) she never stands flat-footed over the bike, so top-tube clearance is usually a non-issue.

For the captain, on the other hand, it’s a good idea to know most of the details about how his fit will be accomplished.  Although his single bike’s dimensions can be transferred, and that’s a great start, beware here too his fit requirements might be slightly different, to accommodate the longer bike and rear-load, as well as possible differences in ride approaches, such as aggressive sport riding on singles versus more relaxed touring on the tandem.  Everyone’s preferences and cycling goals of course are different, but these are the things we consider.

Finally, if you haven’t yet much tandeming experience, beware you will both likely spend far less time out of the saddles than you do on your singles, at least initially.  When only on our single bikes we tend to thoughtlessly make adjustments, stand, and accommodate comfort needs automatically.  Very little happens on a tandem without intention, forethought, and verbal communication, especially at the beginning, so we tend to just sit and pedal until issues become unbearable.  Remember too that the captain must be able to very confidently stand over and stabilize the bike, sometimes on un-even terrain, with the stoker mounted.  This doesn’t affect how the bike should fit him while pedaling, but it might be a factor in determining its basic size.

We always used to do at least a full fitting for the captain, and sometimes for the stoker.  We would certainly confirm basic dimensions for the stoker, but occasionally customers already knew what they wanted, which is great too.  We would however insist on finalizing fit details once the bike is built and ready to ride.

lubricating a chain

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Never forget the most important factor in a well-running drive-train is cleanliness, and this dramatically affects the frequency at which you should be lubricating your chain.  As a general rule I recommend applying fresh lubricant every 100 miles (160 km) ridden plus after each ride in wet conditions.  For most folks this is likely a bit frequent, but it isn’t long after practicing regularly before you can determine for yourself when to clean or lubricate your drive-train.

Note that if you intend to switch to another brand or type of lube, the chain should be clean to start.  Some lubricants very much prefer to start on bare metal, so this may require removal and soaking in biodegradable degreasing solution.  Hopefully you’re happy with the lube you’ve been using, so you can simply add oil and clean all in one process without removing the chain.

Rather than allow old and dirty or excess lubricant to overspray or drip inside your house, this is best done outside, or at least in your garage.  Hanging your bike, using a repair stand or car-trunk/hitch rack, works great.  All you really need though is to lean the bike, standing on its wheels, fairly straight and upright against something solid.  The drive-side should face you, and pedals and chain can spin freely backwards without striking anything.  If you’re feeling especially clever you might find a way to secure the bike so it leans toward you slightly, helping to prevent excess lubricant from spattering onto your rim’s braking surface.

You probably have two options for application: drip and spray. Drip is usually more economical, is certainly less wasteful, and easier to control.  With spray you’re paying more for the propellant and spray mechanism.  Although spray is faster to apply, it is also messier, and usually requires more time and effort to clean up afterward.  For either option you will also need a dry shop rag or a couple paper towels.

Using a drip:
Choose an easily identifiable link, such as the reinstallation pin or “master” link, if possible and position it on the lower section of chain just behind the front sprockets.  Carefully drip one drop of your favorite lubricant on each roller all the way along the lower chain until you’re as close as you can comfortably get to the derailleur pulleys beneath the rear cogs.  Stop, and rotate the crank backwards just enough to move the most recently lubed link forward to behind the sprockets again.  Repeat beginning from there, applying along the chain until you reach the pulleys.  After doing this about 3-4 times you should be able to tell that you’ve reached the first link you lubricated, the entire chain is oiled, and there’s no need to go further.

Put the bottle of lube down and spin the crank backwards several times with your right hand, allowing the chain to flex over the gears and through the pulleys, permitting the fresh lube to penetrate the tiny rollers in the chain.  Now pick up a rag or paper towel and, gently wrapping your left hand around the lower chain, continue rotating the crank (with your right hand), drawing the chain through the rag in your left hand.  You can stop and re-situate the rag as many times as you like.  If it becomes saturated before you’re satisfied, switch to a clean rag, spinning while you wipe off the excess.  What you’re trying to do is wipe off any lube from the exterior surface of your chain.  Don’t worry… you’ll never get it all, and what you do get should not be there anyway.  The lube that will make your chain run smoother has already penetrated and you can’t wipe it off. What you are wiping away however includes lots of road grime and abrasive dirt, so you’re lubing and cleaning simultaneously, and minimizing the excess that could attract more grit, which wears your chain and gears as you ride.  All the lubrication your chain needs will remain inaccessible beneath the rollers.

Using spray:
This is nearly identical to the above procedure except that you simply spray the chain, with your left hand, just as it passes over the rear cassette cogs while you rotate the crank in your right hand.  This generates quite a bit of over-spray, and you’ll want to be careful not to get much on the braking surfaces of your rim, or rotor if you have disc brakes.  One nifty thing about doing it this way however is often you may feel in your hand a noticeable drop in resistance, especially if some time has passed since the last time this was done, serving as a demonstration of how beneficial a lubed chain can be.  Again, when you’re finished, be sure to wipe off all the excess you can with a rag or paper towel.  This keeps the chain relatively clean, which is just as important as keeping it lubricated.