Thursday, June 7, 2012

A Serious Assertion
Concerning the post Soma Smoothie Impressionism.  This post will correct some misinformation contained within.

"The one aspect of the bicycle's set-up I do not like is the IRD crankset they fitted it with. There is nothing wrong with the crankset itself, but it is not entirely compatible with what is otherwise a Campagnolo drivetrain. This causes problems when shifting from the big ring to the small, throwing the chain unless I press the lever very gently. "

This statement ignores basic bicycle mechanics.  There is no such thing as an incompatible crankset in the sense being referred to here.  All modern double cranks have roughly the same chainline, meaning that the center line of the crank (between the two chainrings) is basically the same distance from the center line of the bike on all bikes and lines up close to the center of the cassette on all rear wheels.  The standard for double road cranks, is about 43.5mm and has been the same from 6spd through 11spd.  With this in mind, all modern front derailers will work with all modern cranksets (assuming you use the correct shifter).  If the chain is being thrown off the inside, the solution is to adjust the inner limit screw to keep the derailer from moving far enough to push the chain off the inner ring.

I am still trying to decide what to do about this issue and might try to get a local bike shop to loan me a Campagnolo Veloce crankset and a suitable bottom bracket." .

This, as we have seen, is not the most elegant solution.  It will work, but only because the mechanic will likely readjust the limit screws and front derailer before sending the bike out the door.

It is not about the shifters; it is about the crankset's compatibility with the rest of the drivetrain. It uses a different BB width than a Campagnolo crankset would and that is the heart of the issue. A little complicated to go into beyond that."

Actually, it is not complicated at all.  First of all, the “BB width” mentioned in the quote was a common mistake.  All English threaded BB’s (like the Soma) have the same width, 68mm.  This is determined by the frame, not the crank.  The correct term is spindle length, the length of the spindle to which the crank is actually attached..  Each company produces cranks using different measurements.  In order to maintain a proper chain line, each crank must use a bottom bracket with the correct spindle length for that crank.  For Dura-Ace, the last non-integrated spindle was 109.5mm long.  For the Campagnolo Chorus crank of the same age, the spindle was 102mm.  Both put the chainrings on a 43.5mm chain line.  Chain line information is difficult to come by for more modern cranks simple because the standard is set and it is assumed that every modern double will have a chain line close enough to 43.5 as to make no difference. 

In an attempt to find a solution in the comments,  David asks "Have you thought about using a Chain Watcher or similar device to solve your front shifting issue? I use one on my all-Campy drivetrain to prevent rare but dangerous missed shifts on steep climbs."
They included one with the build and I removed it. Those devices have their own potential dangers and IMO there should be no reason to use one on a well-adjusted double."  The problem is that the double is obviously not well adjusted.  When it is, there will likely not be a need for one unless the bike is being ridden on rougher roads or unpaved roads.  The later comments concerning the dangers of chain watchers, that the chain can wrap around them, are largely unfounded except for anecdotal evidence.  Chain watching devices are becoming very common in the pro peloton and are standard equipment for rougher races like Paris-Roubaix.  If they truly did cause more problems than they solved, pro teams would be very unlikely to add them to their bikes. 

On a less technical note, there are some issues with the starement "  The tires are supple and feel wider than 23mm; I quite like them. " followed by the statement" The wheelset they used is also pretty nice." and a picture of some silver velocity rims but no additional information.  Is it possible that the rims are wider than the standard 19mm, causing the 23mm tires to feel wider?  This type of detail is necessary if a reader is to take anything away from the review.
Aside from minor technical issues, there is an overarching theme that must be brought to light if we are to take the assertions of an incompatible crankset seriously.  And that is that the builder of the bike, Soma, assembled and shipped a bike that did not function properly.  If we are to believe that an adjustment will not fix the issue, then we must assume that the mechanics at Soma either do not understand basic bicycle mechanics or that they did not care enough to properly equip and test the bike before sending it out.  More than just the supposedly minor issue of getting a loaner crank from a local shop, this post lays the claim that Soma employs an ignorant or careless staff, a serious assertion towards a company who just sent out a free bicycle.  And an assertion that should not be taken lightly.  

I personally believe that this is neither fair or true.  In my experience, Soma is a quality company who would not send out a bike with incompatible components.  They would expect, however, that a bike would be completely and properly adjusted by a professional mechanic as it was being assembled in the receiving end.  They would also expect that the customer would question and check that adjustment before assuming that the issue was due to incompatible parts and a bad build.  This review of the Soma Smoothie is naive at best and insulting and damaging at worst. 

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