Salsa Fargo - Lemon of the year!

[Galloper]

Hmm!   This is all getting rather serious.   Looking back over the posts there are 5 Fargo owners who are happy with their bikes and two, Johnnyo and myself, who have had major handling problems.   Add in a couple of defective forks and it's all starting to look rather dodgy.

I don't know how many Fargos Salsa produce and sell each year but with 2 out of 5 experiencing problems, that's about a 40% failure rate.   In terms of product quality that's disastrous!

I think Salsa now need to get to the bottom of this fairly quickly before someone gets spat off in front of an 18 wheeler.

[johnsondasw]

This sounds like a high school math problem.  I just retired from 30 years teaching same.  If there are 5 happy riders and 2 with problems, then there are 2 out of 7 with problems, so more like 28-29% with problems, not 40%.  Still not good, but better!

[whittierider]

An extra reason to take shimmy seriously (it was deadly in this one):
http://archive.mailtribune.com/archive/2004/0915/local/stories/01local.htm
It appears she didn't know about clamping the top tube between her knees though.

[Galloper]

Johnsoddsw, you got me.   I was thinking more of the forks and the defects but my typing fingers ran away with me.   To make it even worse, as soon as I posted I thought 40%?   Oops!   OK, the virtual beers are on me.   Pint of Theakston's Old Peculiar all round is it?

[TwoWheeledExplorer]

An extra reason to take shimmy seriously (it was deadly in this one):
It appears she didn't know about clamping the top tube between her knees though.

It also sounds like her brakes failed. I keep thinking that the disc brakes on the Safari were/are a very good idea, even if it was a royal pain to find a front rack that worked with them. In a failure scenario like that, aren't motorcyclists taught to lay the bike down?

Proceeding on...
Hans

[whittierider]

It also sounds like her brakes failed.

I re-read the article, and all indications are that there was nothing wrong with her brakes.  I have however read that when a shimmy starts up, applying the front brake (any kind) can sometimes make it worse.  In any case, there's no chance that both brakes would have failed at once.

As for rim brakes, the only problem there is not a lack of braking (our tandem's inexpensive rim brakes can lock up even the front tire on pavement, wet or dry, with only one finger on the lever) but that excessive rim heating raises the pressure too much in the tires, and they can blow.  The solution, if you have only rim brakes and think it may be a problem on a descent you're about to do, is to let some air out first, so the pressure increase from the heat does not present the danger.  Re-inflate after you reach the bottom and the rims have cooled.

In a failure scenario like that, aren't motorcyclists taught to lay the bike down?

I don't know, but motorcycles can brake with the engine too, unlike non-fixed-gear bikes.

[Galloper]

As a motorcyclist of many year, yes, the idea is that you drop the bike on it's side and let it go.   The problem is that there's a natural tendency to hand on as long as you're upright.

I'm a bit ambivalent about disc brakes on cycles.   Like whittierider, I find rim brakes more than powerful enough.   They also seem to offer better modulation than disks.   I have to be quite careful on my mountain bike not to get over enthusiastic with the brakes as they're much more powerful.   Having said that, I found the disk brakes on the Fargo excellent and well modulated.   

[JayH]

I have the little brother to the Fargo, the Vaya with Avid BB7 mechanical discs.  I have not noticed any shimmying even when flying downhill at 45mph (coming down off Mt Utsayantha in Stamford, NY), although at the time I did not have any racks on it and was just out riding the Catskill Scenic trail and decided to take this little detour in Stamford.     The disc brakes are very strong but I didn't feel too concerned about emergency braking, but like all things new, I am trying to learn and get more familiar with discs as this is my first bike with disc brakes. 

Jay

[waynemyer]

Could it be that the introduction of aluminum frames caused the design of steel frames to be perverted in an effort to take weight out?  Could it be that it is just too expensive to make steel stiff enough for a touring bike?  Do you need to add super exotic stuff?  Why can you just make the tubing diameter bigger?  Your more of a materials scientist that I will ever be, whitierrider, what is your take?

As someone with a degree in acoustics, I can answer this.  Without diving headlong into math, shimmy on a bicycle is a function of resonance (recall the failed Tacoma Narrows Bridge?).  The rider reaches a magical combination of speed, damping, and wheel and frame oscillations.  Specifically, the headtube begans to rotate around the contact patch of the front wheel because of elasticity in the toptube and downtube.  Shimmy always occurs at specific speeds. 

All objects and systems have resonance.  The key is to design the system so that modes of resonation are outside of any conceivable parameters.  You may have experienced similar engineering in audio speakers: concrete or MDF or some other material that places the resonance frequency of the system way outside the realm of normal operation.

Handling shimmy is a matter of knowing what to do.  Imagine just one line, reaching between the saddle and headset.  With shimmy, the string vibrates.  Clamping the handlebars locks in the endpoints of the system, enabling it to vibrate better (imagine a tightened string, as opposed to a loose one).  Clamping the top tube between the legs adds another node to the vibrating string, most likely radically changing the resonance frequency and placing the resonance outside the current available modes.  Lifting off the saddle lengthens the string also changes the resonance frequency radically.

[waynemyer]

As a motorcyclist of many year, yes, the idea is that you drop the bike on it's side and let it go.   The problem is that there's a natural tendency to hand on as long as you're upright.

That is very antiquated advice.  No motorcycle safety riding course suggests laying down the motorcycle in a panic situation because as soon as the bike is down, the outcome is down to dumb luck and you have zero control over the dynamics.  Rubber and brakes stop the bike very well.  Chrome and plastic do not.

There are times that riders will dump and advanced courses teach how to bail safely and how to identify that a fall is inevitable.  Done correctly, the rider will often end up standing and still holding the bike in a manner that allows it to still be controlled.

[whittierider]

Clamping the top tube between the legs adds another node to the vibrating string, most likely radically changing the resonance frequency and placing the resonance outside the current available modes.

Unlike using a finger to press a string down on the fingerboard or an instrument, or even touching the string at the right place to get harmonics, I'd say clamping the top tube between your legs is a damper.  It doesn't just change the characteristic impedance or reflect energy, it absorbs it and does not give it back, like shock absorbers in a car which don't just change a resonance to keep the wheel from bouncing, but actually turn the energy into heat.

[waynemyer]

Unlike using a finger to press a string down on the fingerboard or an instrument, or even touching the string at the right place to get harmonics, I'd say clamping the top tube between your legs is a damper.  It doesn't just change the characteristic impedance or reflect energy, it absorbs it and does not give it back, like shock absorbers in a car which don't just change a resonance to keep the wheel from bouncing, but actually turn the energy into heat.

No, the vibration is still there; the frequency is simply shifted outside of the resonance of the system.  There is a small damping effect from skin, fat, and muscle, but all that energy was not suddenly sunk by the legs.  This is exactly like pressing an already vibrating string into the fingerboard (or more precisely, moving one's finger along a fretless fingerboard).  The frequency has now moved outside of sustaining excitation period of the top tube and downtube.  If one could clamp the legs at an exact harmonic point, the shimmy would continue unabated.  This would be exactly the same as touching a vibrating string at its precise midpoint.  It keeps vibrating despite the small damping effect of the fingerpad.

[whittierider]

I think high-speed close-up photography during a shimmy would show that the top tube and down tube have virtually no flex compared to that at the headset which is purposely intended to be a hinge.  The shimmy is mainly that the headset is rotating back and forth at about 5Hz.  Pressing your finger down on a string produces a discontinuity in the characteristic impedance of the transmission medium, causing a reflection of the wave.  The legs against the tube OTOH reflect virtually nothing.  They are inelastic, giving a very high return loss, acting more as an attenuator, absorbing the energy like the deep wedges or pyramids made of open-cell foam, fiberglass, etc. for the inside surfaces of an anechoic chamber by Soundcoat, Azonic, Foam Factory, Auralex, and other companies you're probably familiar with.  The energy is turned into heat.

[Galloper]

On the matter of clamping your knees on the top tube, that had absolutely no effect whatsoever on the Fargo, it was one of the many things I tried.   The interesting thing was how the shimmying came in at various speeds.   Roughly speaking, the first band was 4 -7 mph, the second 11 to 14 and the third 18 to 22.   I spent a lot of effort trying to stay in the non-vibrating areas.

On the subject of laying the bike down, this was a technique I was made aware of on both a Police Advanced course and during a race school.   Just to be clear, it is a matter of last resort, to be used when the alternative is lobbing it over a cliff edge or imminent contact with the Armco.   The decision comes down to gravel rash or serious injury, possibly death.   In the case mentioned, it would have saved that unfortunate woman's life!

Brakes and rubber are indeed preferable as long as they are still effective.   

[EnduroDoug]

For what it's worth, I bought a 2009 Fargo frame/fork yesterday at an unbeatable price ($375 brand new!). It's very easy to allow a couple of negative accounts convince you to steer clear of a purchase. IThe internet has given us nothing if not the ability to cast doubt into every decision we make in life. Though I appreciate the head's up by the original poster in this thread, I decided to trust the overwhelming positivity expressed in this thread on MTBR.

http://forums.mtbr.com/showthread.php?t=467422&highlight=Salsa+fargo

I intend to take my time building it up over the fall and winter and look forward to using it on a 9-day Olympic Peninsula road/fireroad tour next summer. The speed-wobbles will surely be on my mind when I take it on the first loaded spin down a nearby hill, but I'm going to assume the problem isn't terribly common or won't rear its head for me.

And if it does... buyer beware. At least I know Tim @ salsa will likely be there to help me get it straightened out.