The Mysteries of Bike Assembly

[Michael Hechmer]

Since retiring I found that my Trek 620 commuter wasn't seeing much use, and after I bought a Saluki on this list I pretty much stopped riding it all together. I tried selling it but no one made me a decent offer and I liked the ride too much to just give it away.  When someone offered a good set of NOS 650B wheels I decided to go ahead with a long standing plan to convert this bike and add S&S couplers to the frame.  Had to move the canti studs, added DT studs and had it powdercoated, all by Bilenkey.  Pictures here: https://www.icloud.com/photostream/#A2GgZLKuGQYuu6   Sorry about the fuzziness but I find it very difficult to hold an iphone steady enough to take decent pictures.  Other than the wheels, all the parts are stuff I had on hand.

Anyway, every time I put a bike together I find myself wondering about why some things are so much harder than they have to be and why the bike industry hasn't made any attempt to ease the process.  Don't get me started on the bright idea of putting one chainring bolt in backwards! Cables puzzle me the most.  First, threading cable into aero brake levers.  If your light isn't perfect, or your eyes are over 50, or you're working with a used cable that has the slightest bend in it, you will struggle.  Why not make the entry point funnel shaped, or the anchor slotted, or removable, or even make the top of the lever housing removable?  How hard would that be?  Second given how much the industry has worked to reduce inventory (steeply sloping TT & ahead stems for example) why do we still have two cable sizes with two different size housing, two different ends, two different caps and crimps?  I understand that brake cables need to be stronger than derailler cables do, but derailler cables don't need to be weaker.  In 35 years of riding the only cable I have ever broken has been a rear derailler.  I was a long way from home and would have been much happier with a stronger derailler cable as there were a lot of hills for me to negotiate on a single speed bike!  This time the cable disconnects created another complication.  If you haven't used these, the female end of the connectors house a cable end.  But that end is sized to work perfectly with derailler cable.  The brake cable end needs to be filed down in order to fit loosely enough to allow the part to turn.  This is in spite of the fact that they made the brake cable hole a tad larger.  In contrast the male end holds the cable with two set screws, but the entry hole in the brake connect is much smaller than the exit hole and, to my eye, just barely distinguishable from the derailler connect.  I think I spent half the time on this job playing with cables!

Now I'm going to take it on a shake down ride, then disassemble, pack it in a suitcase and fly to Oakland on Tuesday.

Michael

[Tony DeFilippo]

Michael,

Congrats on your new build!  I'm quite fond of the older Trek's myself and converted what I believe to be a 1982 715.  I'd considered the Bilenkey S&S, re-paint route as well but I was able to get side pull's that reach the 650B rims.  My 42mm EL Hetre's just barely fit, getting the stays crimped a bit is something else I'd have done if I went the route of major frame work.  What a cool bike to have, seems like you've given it a new lease on life!

On the mysteries of bike assembly you bring up a bunch of amusing and common sense points, looks like you made it work!

Tony

[hsmitham]

Michael,

Very insightful regarding all those points especially the funnel shaped entry point and cable size. I suspect some would say the derailleur cables needs to be a smaller diameter so the cable flexes a bit more especially at the rear with all the curves. I'm just guessing here as I am no expert.

The Trek looks fantastic! Isn't this the second Trek you've brought back to life? Anyway good job and enjoy the trip to the City in the West.

~Hugh

[Perry]

Some excellent points. Regarding the cable splitters...

> In contrast the male end holds the cable with two set screws, but the entry hole in the brake connect is much smaller than the exit hole and, to my eye, just barely distinguishable from the derailler connect.

I have davinci cable splitters and find no problem distinguishing between brake and derailleur easily. Not sure that the brand would make any difference but just throwing it out as a data point.

Regarding 50+ year old eyesight, I'm 55. This is my main problem working on bikes. This and diminished dexterty of my hands/fingers and loss of general flexibility (to bend and hold my body in certain situations while making repairs). For the flexibly part, I find myself moving the bike on the stand more often to get the best angle at the job. Good readers that don't slide down my nose and this http://www.lightsandknives.com/images/D/hl4.jpg are the best I've been able to come up with for the eyesight thing. I remain open to suggestions.

Also, as noted, I strongly suspect that a brake cable will not be be flexible enough to give optimal shifting performance. This may be most noticeable around tight bends such as under the BB cable guide to front derailleur. Also, could be that this is more of an issue with indexed shifting. I realize these standards were established prior to indexed shifting so maybe I'm wrong about the reason but I've done some experiments and the stiffness of a thick cable does appear to effect shifting IME.

• Perry

[Michael Hechmer]

No doubt derailler cable needs to be more flexible, but I'm betting we have reached a point in material science where we can make a strong  & flexible cable.

Michael

[Ron Mc]

making cable housings too short leading to excessively tight bends is the most common demise of cables.  

My buddy had a short derailleur cable that shifted on him from frame flex under a climbing load (exactly where you don't need it)

Lengthening the cable housing solved the problem.  

[Bobish]

True, perhaps. But now standards have already been established. Changing at this point = Giant Pita.

• Perry 

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[WETH]

In the middle of my own assembly project, I found your observations quite valid. The Trek looks great. Safe travels and enjoy the riding in California.

[Nick Worthington]

For what it's worth, I'm working on an early '70s all-Campy bike, and all the cables are the same thickness.  (brake size)  Different cable heads though.  Don't know if it would matter, but I went ahead and sprung for NOS derailleur cables, Just in case.  On the other hand, I have English and French derailleurs from the '40s and '50s that use the thinner cable.  So who knows....

Nick

[Michael Hechmer]

Good thought only this bike, and the bike where the derailler cable failed were both DT shifters, hence no cable housing at all.  The tightest bend is clearly around the DT shifter itself. All other bends are much less than that.

[Ron Mc]

Thicker cables are more apt to fail at the shifter drum than thinner cables.  The most damaging things that happen to cables are always the clamp screws.  

[Steven Frederick]

FWIW, SRAM makes (or made) shift cables that were a teeny bit thinner than typical.  I think they were meant for grip shifters but I should imagine they'd work with other types too...

Steve

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[Tim Gavin]

The newest Campy shift cables are 4.1mm, down from 4.5mm "normal" shift cables and 5.0mm brake cables.

Segue:  I recently rehabbed a 1988 Schwinn Project KOM-10 as a commuter.  It came with a rear chainstay U-brake and front cantilevers (Deore XT M730).  The original brake cables were heavier gauge than standard.  I replaced them with stanard gauge brake cables.  Should I be worried that they aren't strong enough?

With Kool-Stop MTN pads on the brakes, they grab just fine, U-brake or not.

Tim

[Kieran J]

Hey Michael,

 

How are you liking the 620 as a conversion? I'm wondering about doing a similar route with a 1983 620, and I'd be interested to hear your impressions, comparing 700c (or 27" I guess) to 650b on the same frame.

 

Kieran