Sherpa Shimmy resolved with superb warranty response by Thorn Cycles

[Pavel]

Easy fix Dan.  Buy a Nomad!  The fates are saying you should!

[sg37409]

I would suspect the rack top bag also. I've had a few bikes to this to me, (both thorns, though not sure its anything to do with that) and in the end, was pretty sure it was the bag.
A few other factors came into play,
a) how quickly I got up to speed & the wind  - almost like if not sufficient drag on the pack, then it could start me shimmying
b) how loaded the bike was, by which i mean, did the road drop real quick, unloading the tyres ? (Linked to how quickly i got up to speed)
c) Could I get thru the wobble-zone ? Always felt like I could, but in the end never had nerve to try.

I used to apply r.brake lightly if/when it happened to keep me just under shimmy speed.
Both bikes behaved fine on nigh on all occasions subsequently.

hope you get it sorted and get back to enjoying the descents

[Danneaux]

Hi All!

Back with an update after a lockout by my ISP that left the Thorn domain inaccessible to subscribers here in the States. Here's the latest on the shimmy, and it is very hopeful...

More testing
In two days, I made over sixty 25-mph runs up and down in front of the house, checking every possible load permutation and arrangement. It didn't help that a steady rain began to fall shortly after I started but I kept at it, getting so tired I nodded-off during dinner.

I had a strong hunch the problem was likely to be the rack-top load, but I decided to let the testing remain neutral, stay with scientific method, and see what the data said.

First, I stripped the bike and added weight starting from the front (detailed in my last post) , figuring excessive front weight might be a trigger.  Loaded only at the front, with front panniers, HB bag, the two 2-liter bottles at the steerer and the three 3-liter bottles on the frame, all was wonderful. Adding only a rack-top load added (11lb/5kg) /or/ the two rear panniers (25lb/11.3kg) was fine; things went sour when both were added at once.

Then, I stripped the bike once again and started adding loads from the rear. With either a rack-top-load or rear panniers, all was fine. With both, the bike felt really unstable, and rocking the front end at rest pointed up the instability. I kept adding weight going forward, and things got better in some ways and worse in others. The overall stability was far better with ballast in front, but the top tube soon developed a sine wave and little changes moved the shimmy up or down in speed. The rear load appeared completely stable on examination.

Results? -- hopefully!
Persistence pays. The more I tried, the worse things got. Looking closely, the most likely culprit seems to be the Surly Nice Rack (Rear) (Pete wins the prize for this one!). It grew much more wobbly and weak as the tests progressed, and now it can be shifted 1cm with gentle lateral finger pressure against the rear struts. Looking closely, it is an untriangulated, 3-sided box. This design gave me problems when I bought a Surly Nice Rack (Front) for the Miyata 1000LT that preceded Sherpa, and I ended up selling the rack -- unused -- on eBay. The Surly racks are made-for-stout, are really heavy, and have tremendous strength under vertical loads. Unfortunately, without triangulation, they have little resistance against lateral movement. What really tips the scales is the mounting hardware. It is wide front-to-back and vertically, but narrow side-to-side. Despite all the heavy tubing, the mounting points come down to squashed tubes about the thickness of a washer. Those mounting points are also stainless-steel, which work-hardens pretty quickly. I wouldn't be surprised to find some micro-cracks when I remove it. In contrast, the triangulated Thorn Low-loader Mark V front pannier racks are no problem.

A Solution? Maybe!
I have sent for a new Tubus Cargo Evo rack. It is a new design for 2012, and represents an evolutionary development of the world-tourist's standard, the Cargo. The top deck has a closed "Return" at the front, and has a narrower load deck to aid in triangulation. It has die-stamped, 3-D mounts at the dropouts, and looks to be a structurally sound design. Though it weighs only half what the Surly weighs, it is rated to carry 8lbs more. The price really hurt at USD$140, but if it solves the problem, it would be cheap at twice that, as it would set everything right.

It is on the REI truck being driven down from Seattle, and should be in to the store for me to pickup today. I'll install it sharpish and take it out for more test runs. I must have pretty good cardiac health or I'd be dead from all the interval training. In car-centric 'Merka, the neighbors have me pegged for a nutter so I've nothing to lose on that score.

I so hope the present rack is the culprit and the new one will solve the shimmy problem. As an (amateur) frame designer and builder, I know the precipitating factors in the usual shimmy -- various influences of weight and weight distribution, coupled with gyroscopic precession of the front wheel secondary to trail and over-damping of same -- but this was different. The real clue (if I had been smart enough to see it earlier) was the entire shimmy could be simulated with the fully-loaded bike at rest. Simply by rapidly turning the handlebars, a sine wave could be introduced through the top tube. It was made far worse when the rear brake only was locked, providing a pivot point and axis for the wobble at rest; my weight did the same while riding. The test data indicate this is a classic case of "the tail wagging the dog"...in this case, precipitated by a wobbly rear rack.

Updates to follow when the new rack is installed, loaded, and testing is complete.

Best,

Dan.

[jags]

great to have you back Dan, hopefull the new rack will solve the shimmi problem.

[il padrone]

A bit sad to pass this on after your purchase, but you do know about The Touring Store ? Waynes prices are quite competitive.

Hopefully the new rack should be a lot better for you anyhow.

[Danneaux]

A bit sad to pass this on after your purchase...

Not to worry, Pete, and I appreciate the suggestion. Yes, Wayne's prices are very good, and I have dealt with him before and found him very good. In this case, I tried my best to weigh my options. USD$120 or $140 is a lot of money to me, and I cannot tell if the new rack will a) fit and give the clearances I need or b) will solve the problem.

Wayne is really good about returns, but very understandably, he needs items returned in the same unused condition as when they arrive. Often, when I have a question, seeing the product in person or measuring it carefully for clearance or just holding it up is enough to answer any remaining questions without installing it, but in this case, I will have to at least carefully mount the rack and then (after wrapping it with tape) mount the bags to see if it is stable under load and addresses my shimmy problem. There is a risk and possibility the mounting hardware could show slight marks, and then it wouldn't be returnable to Wayne.

I don't return things frivolously to REI, but I figured in this case, it would be worth the extra $20 (free shipping if it is sent direct to the store for me to pick-up) to answer all questions. I fully expect this to solve the problem and I can't imagine returning it, but...well, I guess you could say it is peace of mind "just in case" the unlikely happens and it doesn't work. One thing that concerns me a bit is Tubus' cautions about tire and fender clearance. Of course, I can only see their measurements in plan view, but they say the rack limits tires to 50mm and fenders to 55mm. I have both. I also have a lot of (needed) clearance between fenders and tire, so I don't know if that will push me into an interference fit or not (the triangulated rear brace is formed into a narrowing, inverted "U" and could potentially strike the fender edges depending on how high the fender rides compared to the rack dropout mounts). If it goes wrong, I can return it to REI for free in person. If it went wrong and I had to return it to Wayne, it would cost me about $20 in return shipping, making the price difference a wash.

At this point, I'm just biting my nails hoping the new rack does the job. It should have arrived at the store yesterday or the day before, but REI's policy is to co-load their trucks with local merchants to reduce overall carbon footprint, so the trucks often take a "milk-run" on the way down from Seattle. Also, it is the weekend, and local store staff may not yet have had time to scan the arrivals, bring them upstairs, and then store them on the rack system before notifying me with an email for pickup. The official "due date" is Tuesday, but I'm really hopeful for arrival soonest so I can lay my concerns to rest.

Good suggestion, though, and most welcome; thanks!

All the best,

Dan.

[rualexander]

I get some shimmy on my Sherpa when I have panniers on (front and back). It starts at 20mph and eases off again around 25mph, it's not severe and dampens out with a knee against the top tube. Seems to vary depending on the load in my front panniers which are fairly big (older style Altura Orkney model) and probably sometimes a bit overloaded as the right hand one is my food pannier.

[Danneaux]

Hi All!

Next chapter...

What's this?!?
The Tubus Cargo Evo rack arrived at REI today, and after mounting, it didn't look right. I discovered in fine print on the packaging...they had mis-filled my order at the warehouse! The rack I received is the one intended to fit even a "29er", a bike running really fat MTB tires on 700C rims and/or 26" bikes, the latter leaving an awful lot of clearance above the rear fender. It is ridiculously tall on Sherpa with fenders and 26x2.0 Duremes, and because of the height, I cannot fit the previous load atop the rack because it won't clear the Ortlieb underseat tool bag. Despite the published specs saying there is a 13mm/.5in difference in height, the sticker on the hardware package with this rack claims a "+2cm" designation, more than .75in. The lower model would still clear the rear fender by quite a lot...and I'm running pretty generous fender clearances.

Since the rack is now mounted to the bike, I will go ahead and test-ride it and see if it fixes the handling problem. I have placed a new order for yet another of the proper size, it will arrive in a week (another week! More delay...), and hopefully the order will be filled correctly and all will be well.

Observations; "Evo" does indeed mean "developed further"
Meantime, I have some observations about the new-for-2012 Tubus Cargo Evo in my possession...
1) It is not made in Germany or the Eurozone, but in Taiwan, according to the plastic bag that contained it.
2) The little plastic tube end plugs...all mine were missing but one. They're poor-quality plastic and a little undersized. They must have fallen out in handling at some point before ever reaching me.
3) Unlike earlier Tubii, this model is not brazed, but TiG-welded. I think this may be a good thing. It always concerned me the brazed side joints on early Tubus racks weren't coped or mitered in any way. By welding, the steel is actually melted together. Sure doesn't look as neat, however.
4) The finish is incredibly fragile, at least compared to the Surly. One single fitting of the pannier hooks left permanent marks. If it matters to someone, the finish is well toward the glossy side of satin, rather than matte.
5) The tube diameters are the same as the Surly at 10mm, but the 11mm Ortlieb hook adapters rattle noticeably compared to the Surly. Leaves a lot of room for anti-scratch wrapping. No protective "foil" tapes were included as in the past. This point is made in the instructions.
6) The mounting instructions on Tubus' website are labeled a "Preliminary Version!". And is! Even the instructions that arrived with the rack shows fastener types that do not match what came in the package, and the designations are "off".
7) Unlike their earlier racks, Tubus chose to use Torx bolts to hold the mounting rods and hardware at the front of the rack. Though the instructions designate them as T25, they are really T20...an odd size not many cyclists would already carry. The remainder of the mounting bolts are stainless allen bolts (though the instructions designate all-Torx). The Nylock-style nuts weren't very grippy; I'll use Loctite if I keep the rack. I'll also probably substitute stainless hex-head bolts for their ease of use and greater head-torque rating.
8 ) The stainless steel mounting hardware was really crudely machined with lots of tool marks and no cleanup. I found this out when I slid one eyebolt over the black-anodized forward mounting strut...and left behind a trail of silver scratches through the anodizing. I had to go to work on the second one with my jeweler's and riffler files to get it to fit at all.
9) Tubus' new "3-D" lower mounting bracket is not stamped as has been reported on the 'Net. Instead, it appears to be an investment casting. The mounting hole would accept a 6mm bolt. Unfortunately, the well for the bolt precludes use of a hex-head bolt (no socket wall clearance), and there is no room for a flat washer beneath the bolt head. Some small-diameter washers were included in the mounting kit, but remained unaddressed in the instructions. I'll bet I know what they're for. [EDIT: Yep; the small washers can be stacked under the lower 5mm allenhead bolt to adjust the effective length of the bolt so it doesn't foul top-gear on the cassette].
10) Unlike the earlier flat, stamped-steel lower mounting plate, the 3-D mounts do not include a mounting eyelet for fender stays. Unfortunately, the rear rack struts come almost exactly over my upper fender stays for the rear fender, causing interference with the rack and pannier hooks as well as noise (the fender stays rattle against the rack struts). Tubus offer a small stainless steel bracket that attaches between the rack's taillight bracket and the rear fender, obviating the need for the upper fender stays. Yes, I will need that accessory bracket. I'm guessing most Thorn owners running SKS 55mm fenders and this Tubus rack would need the bracket also.

The Surly Nice Rack (Rear) has to be the problem
Before fitting the Tubus Cargo Evo rack today, I removed the Surly Nice Rack (Rear). This just has to be the source or at least a major cause of the wobbles. Not only is the rack an untriangulated 3-sided box with squashed-tube mounting brackets with the narrow dimension inline with the frame and offering no resistance to lateral movement...the front two mounting stays cannot be made to stay tight. I know they were tight to spec when I installed the rack, and I used blue Loctite to secure the grub screws. Off the bike, these forward mounting stays are so loose they wobble 5mm each way when I shake the rack. Worse, they don't stay tight. It appears there is not enough captured area in the radius of the mounting spacers to prevent the brackets from moving sideways. Yes, they were secured to Sherpa's mounting bosses, but even so, when the rack wobbled, the stays moved as well because of their thin, narrow mounting points. This would surely (Surly?) explain the origin of the wobble and why it progressively worsened throughout my testing. It wasn't present in earlier test rides with even more weight overall.

The good news is that -- even in a size too large/tall -- the Tubus Cargo Evo is worlds more stable and I really can't move it more than a mm or so in toto with lateral hand pressure at the extreme end of the last bag-stabilizer strut, which is not itself directly load-bearing.

Uh-oh; the Rack Search continues
Trying my Ortlieb BikePacker Plus bags on the Tubus Cargo Evo did point up some differences in dimensions compared to the Surly, causing some problems; these may cause me to consider the Tubus Logo Evo instead:
The top deck on the Cargo Evo is considerably narrower than the Surly (114mm/4.5in Cargo Evo vs 160mm/6.3in). Unlike Ortlieb's Roller bags that end essentially at the top of the stiffener (plus the roll), the Packer bags have a drawstring and overcap closure, which allows them to stand well proud of the rack-top -- 11.4cm/4.5in when full. As a result, the Packers leave a valley between the two caps. If one carries a dry sack crosswise atop the rear rack (as I do; it holds my sleeping bag and pad, silk liner and air pillow), that valley has to be filled to make the dry sack stable in carry. With the Surly's wider rack, I was able to better fill the valley with my 10l MSR Dromedary water bag and a little 3/8" closed-cell foam sit-pad that also protected the rack and load from each other and the pannier hooks. The narrower top of the Cargo Evo doesn't allow for this very well. I can use the Dromedary filled with water or air as a spacer of sorts, but it is really too wide. Similarly, I can put the tent lengthwise on the rack to fill the valley, but it is too tall, making a fulcrum for the drysack to pivot on.

Logo Evo's differ'nt. Way. And maybe better for my needs
The Logo has a second set of pannier-hook mounting rails situated 58mm/2.3in below the rack-top. Although the Logo Evo's top deck is even narrower than the Cargo Evo (85mm/3.3in at the front, 99mm/3.9in at the rear in a wedge shape vs the Cargo Evo's 114mm/4.5in parallel), I think putting the bags and their extended caps lower would allow me to use the caps to effectively extend the rack-top, giving a more stable platform for my rack-top load. The panniers and everything atop them would ride 58mm/2.3in lower, lowering the center of gravity and giving needed clearance beneath the Ortlieb underseat tool bag to get the rack-top load farther forward. The downside? The panniers would have to ride exactly 12.7mm/.5in further rearward to give the same heel clearance. Sounds like a fair trade for more stability and less risk of sway/shimmy. An added benefit? The Logo Evo is rated to clear 65mm fenders and 60mm tires vs the Cargo Evo's rating of 55mm fenders and 50mm tires. It should solve the problem of fender stay-rack interference I have now.

On the downside, I expect the Logo Evo to work miserably with my rack-top pack for day rides. Maybe I can put a stiffener in the bottom of the rack-pack and tie the front to the seatpost to aid stability. The Logo Evo's platform is really too narrow to support such a bag very well. I'll have to deal with that later. Right now, the priority is to make Sherpa expedition-worthy.

So...now what?
I guess the thing to do is to send for a Logo Evo and give it a try as well. Now I know the finish can be scarred by a single mounting of the bags, I will wrap it with tape first and if it doesn't work, off to eBay it goes. It is a little sobering to think I will have USD$400 in racks charged to my card until I figure this out, but I'm getting desperate. Time is my biggest factor. I have arranged my work and appointments for this window in time, and if I have much more delay, it will affect the kind/length of trip I can take (and the four+ months' planning that went into it). Much more delay will also put me into really torrid weather, and that has serious implications for desert travel. Ground temps of 134F/57C are hard to deal with. In midsummer 2010, I ran into air temps of 125F/52C while climbing Fort Rock and it was pretty enervating. Yeah, better to send for a bunch of racks and try them in a short timeframe than miss my departure date by too much. I can always sell the unwanted the racks after I return.

Making the best of the meantime
Meantime, I'll try the too-big Cargo Evo that is now on the bike to see how it works. The shorter, properly-sized one has got to be even stiffer, so if I get good results with reducing or stopping the wobbles with this one, I'll know I'm on the right track.

Any more ideas on this, "the latest"?
Any thoughts or experiences from those owning a Logo Classic or Logo Evo are most welcome also; many thanks in advance. Andre, don't you own a similarly designed Cosmo? Nighttime now, but pics in tomorrow's daylight if I can manage it.

Best,

Dan.

[Andre Jute]

Any more ideas on this, "the latest"?
Any thoughts or experiences from those owning a Logo Classic or Logo Evo are most welcome also; many thanks in advance. Andre, don't you own a similarly designed Cosmo? Nighttime now, but pics in tomorrow's daylight if I can manage it.

Dan:

My experience of Tubus is essentially the same as yours, profound disappointment with their carelessness.

On the Thorn Board, because everyone is so polite and I'm a guest, at http://www.thorncycles.co.uk/forums/index.php?topic=4015.msg18057#msg18057 in the Titanium Rack thread, I was probably not outspoken enough.

But on the rec. bicycle.tech board at http://groups.google.com/group/rec.bicycles.tech/browse_thread/thread/dddd7d2fba2eea3/89e19b1ce3c7d4cf I spoke my mind clearly: "Tubus Cosmo Rack = Expensive Crap for Posers".

I also published first impressions at http://www.freag.net/en/t/1iu8f/tubus_cosmo that were marginally more positive.

My conclusion is the same as yours. The main thing that Tubus gets right is that, once you've provided your own mounting hardware, the rack is rock solid.

In any event, the Cosmo is, in my opinion, a mickey mouse rack, probably marginal even for credit card touring, definitely too small for your sort of touring. I'm amazed to discover you're considering even narrower racks than the Cosmo. The usable (from where a tall load would butt up against the saddle) top surface on the Cosmo is 120mm wide by about 290mm long on my Kranich on which the extra-cost extension mounting kit is used to raise the rack above the huge 60x622 Big Apples and SKS P65 fenders. On a 26in bike you may be able to use the same extra fitting kit to move the rack rearwards for necessary heel clearance for the panniers, which is in fact its intended purpose according to the fellow at Tubus, and then you get a load surface of about 120x310mm. (These measurements, compared to what you give for the other Tubus racks, make the Cosmo sound positively desirable by comparison! I really wish a proper German maker, say Humpert who now owns SL, would make a stainless rack, perhaps on the superb old SL pattern.)

I've kept the Cosmo because it is rock solid (once you bring your own bolts, nylock nuts or Loctite, and pay extra for the fitting kit), doesn't rust, and its permanent shortcomings don't really matter in my kind of use: all I hang on it is an open-top pannier basket that rarely gets taken off the bike so that the angled lower rail is only an intermittent rather than a daily irritation, and all that stands on it is my leather saddlebag, which doesn't need the support because it has a stiff bottom.

If you want measurements of Tubus bits, just shout, Dan.

The problem with obtaining a better rack than Tubus makes -- Madison for instance -- is finding a supplier who has one in stock for immediate delivery. (The only alternative stainless steel rack to the Cosmo is probably out of production.)

Andre Jute

[jags]

sorry your having so much trouble Dan,
i have the classic logo and have to say  i have had no problems  what so ever.
but i dont carry as much as you .
but anyway so far its held up pretty well.

[Danneaux]

Hi Andre, jags; thanks so much for your ideas and input. Very much appreciated!

My conclusion is the same as yours. The main thing that Tubus gets right is that, once you've provided your own mounting hardware, the rack is rock solid.

Absolutely right, Andre. I have found over time that a manufacturer's reputation gets them in the door for my consideration, and user reviews help them along the way toward my purchase. However, it is their actual performance after the sale in meeting my unique requirements that really earns them the gold star...or not.

The one thing Tubus really has going for them is their triangulated steel-tube rack design. Their build quality is in general a bit pragmatic with regards to finish; indifferent when it comes to fasteners and hardware. At this point, caught in my kafkaesque nightmare of trying to get the bike working right again, I really don't care so much about finish and OEM hardware. If it'll work by throwing new nuts and bolts at it, I'm good. It's not lowered standards on my part, but the desperation of a time crunch mixed with pragmatism. I can polish bolt heads or repaint the rack after I return. Right now, it just has to work. Elsewhere...

I spoke my mind clearly [elsewhere, wrt the shortcomings of the Cosmo]...

...passionately and eloquently as usual; glad I read it.

I've kept the Cosmo because it is rock solid (once you bring your own bolts, nylock nuts or Loctite

Just what I am hoping for and intend doing!

I'm amazed to discover you're considering even narrower racks than the Cosmo.

So am I, Andre; astonished! It seems counter-intuitive, but the idea in doing so was several-fold:
1) Drop the cap-top Ortlieb packers to near-rack level, thus extending the effective rack top and increasing stability for loads carried crosswise.
2) Dropping the bags drops the cap-tops and all that rides on them, allowing me to push the rack-top load as far forward as possible, right under the rear of the saddle and close to the center of the wheelbase. This just has to help with the wobbles.
3) Narrowing the top deck of the rack effectively triangulates the entire rack, not just the last strut (the front struts cant inward only mildly on the Cargo).
4) The newer, Evo-series racks come with the cast lower mounting plate which in my tests really does increase lateral rigidity. I really want the Evo mount in a plain cro-mo, heavy-touring rack, and at present that limits my choices to the Cargo Evo and the Logo Evo.

On a 26in bike you may be able to use the same extra fitting kit to move the rack rearwards for necessary heel clearance for the panniers

An excellent suggestion, Andre, and one I will surely keep in mind. If possible, I would like to try other means first, as I want to carry that mass as far forward as possible. Taking careful measurements, I think I can get where I need with adequate heel clearance by moving the bags rearward only 13mm/.5in. Not a bad tradeoff if I can get my bags and rack-top load lower and also move the rack-top load forward.
-------------
As an aside...
I'd never consider trying to convert an Ortlieb RollerUser, but I love my drawstring-closed, cap-top Ortlieb Packers. I use the caps as extra pockets to carry things I need quickly and don't want to dig in the panniers for.  My LF top-cap carries my wool cycling jersey with nylon wind panels. My RF pannier top-cap carries my fleece jacket. My LR pannier top-cap holds all my rain gear in a stuff sack. My RR pannier top-cap holds my off-bike Merrell Breeze II nylon mesh clogs and my chair. This way, I can peel off or add jackets or rain gear, switch shoes and even have a seat while doing so...all without having to remove stuff from atop my rear rack or digging into the bags...just unsnap two plastic buckles,flip the lid, remove the stuff sack with whatever, and put it on...or take it off. I'm addicted to the sheer convenience of it all.
-------------
That's my reasoning, anyway. If the Logo Evo doesn't work, the 26" version of the Cargo Evo is on the way. I ordered the Logo Evo and a mudguard bracket for it (also fits the Cargo Evo) so I won't have to deal with the interfering top stays on the rear mudguard. I decided time is the most important factor, so I went with the FedEx 2nd Day shipping option on this latest rack. It comes from Arizona, so this will help a bit in getting it dispatched, usually the largest delay.

If you want measurements of Tubus bits, just shout, Dan.

Thank you, Andre! A very kind offer, much appreciated by me.

Now, jags...

sorry your having so much trouble Dan. i have the classic logo and have to say  i have had no problems  what so ever. but i dont carry as much as you. but anyway so far its held up pretty well.

Oh! This is welcome news, jags! I am heartened to find they worked well for you in daily use, anyway, even if the loads we carry are different. I've seen your Sherpa but hadn't registered you had the Logo. It certainly made for a nice, clean, well-balanced load in your tour photos. Very good to know.

Thanks, gentlemen; all very helpful to me and greatly appreciated.

All the best,

Dan.

[Danneaux]

i have the classic logo...

Got it, jags. Looks really good on your Sherpa at: http://www.thorncycles.co.uk/forums/index.php?topic=1744.0

Gives me a preview of how it might look on mine.

Best,

Dan.

[jags]

Dan if i could afford the postage i would sent it to you,
dont think i'll be using it for a while .

[Andre Jute]

Just for the sake of completeness, I also published first impressions of the Tubus Cosmo at http://www.freag.net/en/t/1iu8f/tubus_cosmo that were marginally more positive than my mature reflection and evaluation. You can save them for when you return, Dan; there's nothing immediately helpful in there except that hardware store pre-drilled three-hole flat bracing/repair brackets turned out to have the holes in the right place to stand in for the Tubus fitting/raising/distancing kit while it was en route. -- Andre Jute

[Danneaux]

I get some shimmy on my Sherpa when I have panniers on...

Hi Rual,

I've been meaning to ask you for more details on your Sherpa's shimmy. Please, could you tell me what racks you're using front and rear, and about how much weight is in the panniers and atop the rear rack? It sounds as if the problem is weight-dependent for you, and possibly more due to how the weight is distributed. Your shimmy doesn't sound as severe as mine if it can be damped with a knee; mine was unaffected when I "kneed" it. Can you tell me what size Sherpa you have?

I still think it must've been the rack, as it got progressively worse, where it was non-existent to start with when carrying even more weight.

I had to be out of town all day yesterday, so had to postpone the test runs. I try to keep the proper perspective on life, but the non-cycling world intrudes on occasion.  

I've got my jersey and shorts on as I type this, and should know more about how the (too big) Cargo Evo does just a few minutes from now. The Logo Evo is on-track for getting here by 2nd-day shipment from Arizona (in Oakland, California at the moment) and should arrive before 16:30 tomorrow. The proper-sized (13mm shorter) Cargo Evo is due on or before Tuesday.

Whew. With three Tubus racks at my disposal, I should be able to get some good comparative data. I've got a 16x23 matrix all set up to take the data as I get it, but hopefully I'll find myself saying, "Feels better!" or "Solved!" after just a few tries.

Thanks for weighing in with a really important data point, Rual. You're the only other Sherpa owner I've heard from who has experienced shimmy, so I'm eager to learn more.

All the best,

Dan.