Author Topic: Sherpa Shimmy resolved with superb warranty response by Thorn Cycles  (Read 47513 times)

Andre Jute

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Re: Wow! Whoa!...woe. Severe Sherpa shimmy under load.
« Reply #135 on: August 07, 2012, 09:20:07 pm »
i will never carry that kinda weight, i know you need it for your type of touring but i'll stick to plan b tarmac all the way nice and light. ;)

My credit card weighs 30 grams and the fellow in the sag wagon doesn't mind carrying it for me!

jags

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Re: Wow! Whoa!...woe. Severe Sherpa shimmy under load.
« Reply #136 on: August 07, 2012, 09:48:27 pm »
 ;D ;D ;D way to go Andre.

Danneaux

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Re: Wow! Whoa!...woe. Severe Sherpa shimmy under load.
« Reply #137 on: August 08, 2012, 05:55:19 am »
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My credit card weighs 30 grams and the fellow in the sag wagon doesn't mind carrying it for me!
That would be the Titanium card, right? The Silver, Gold, and Platinum cards are simply too heavy! :D

Best,

Dan.
« Last Edit: August 10, 2012, 03:44:06 am by Danneaux »

Danneaux

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Re: Wow! Whoa!...woe. Severe Sherpa shimmy under load.
« Reply #138 on: August 10, 2012, 03:45:21 am »
Hi All!

Thorn Cycles' designer, Andy Blance, has expanded on his earlier views with some load schemes and suggested weights for touring – this time for typical European and Alpine touring with less than the Nomad's maximum capacity. He has kindly given his consent to share his comments for the benefit of the Forum.

Since loads – and how they are packed – directly affect a bike's stability, I think it is helpful to include his recommendations in this same thread. Unlike my more specialized requirements, the greater number of cyclists will likely tour with lesser loads, just as I do when in more populated areas. When I toured Europe for 5 weeks, I carried 25kg...there was simply no need to carry such enormous back-stocks of food and water I require in the wilderness.

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Hi Dan,

Thanks for your email. Fiona and I are more than happy for you to publish our recommendations for loading bikes for touring in Europe, where supplies and services can usually be found every day.

Like you, we really enjoy many different types of cycle touring. We especially like to be at altitude in wilderness and we certainly agree that it is the quantities of food and water which are necessary that produces such extreme loads! The bonus is that these loads reduce…often on an hourly basis!

...I know when Fi and I go cycle camping in Europe, we very occasionally carry as much as 32.5Kg.

We carry either a bar bag or a saddle bag depending upon the type of tour we are planning.

Bar bag set up…ideal for really long tours.  Includes plenty of appropriate clothes for cultural activities.

We aim to carry as little as possible in our bar bags…phone, camera, binoculars, passport, glasses, wallet and bean bag for use as a camera support…this also line the bottom of the bag. Total 1.75Kg

We carry 2 x litre coke or sprite bottles of water in the seat tube and under down tube cages and 1 x 0.75l bottle of drink in the down tube cage Total 2.75Kg.

We carry alternative shoes some provisions and clothes we won’t use during the ride in the front bags. Total 6Kg

We use a large, transversely mounted dry bag with our share of the tent, air mattress and sleeping bags. Total 5Kg

Our rear panniers carry our share of heavier tools and spares,  food, cooker, yet more clothes and hopefully, some wine! Total 17Kg

Grand total 32.5Kg

- - - - - - - - - - - - - -

Saddle bag set up…ideal for serious cycle tours in the Alps. Includes one set of lightweight smart casual clothes, to prevent us from feeling self-conscious, should we decide to stay at a hotel and go out for a meal.

We carry 2 x litre coke or sprite bottles of water in the seat tube and under down tube cages and 1 x 0.75l bottle of drink in the down tube cage Total 2.75Kg.

We carry alternative shoes some provisions and clothes we won’t use during the ride in the front bags. Total 4.25Kg

We use a large saddle bag with a warm layer, waterproofs, snacks, simple tools inc. tubes and a document bag with passport and extra cash .We have all the things we are likely to need for the day’s cycling in our saddlebags. We also carry phone, camera, binoculars, glasses and wallet in the pockets of the saddlebag. If we wish, we can leave all the other kit at a hotel or in the tent and go for a day ride, without having to extensively re-pack. Total 5Kg

Our rear panniers carry our share of heavier tools and spares, food, cooker, tent, sleeping mats, sleeping bags, yet more clothes inc. down jacket, which doubles as a pillow and hopefully, some wine! Total 14Kg

Grand total 26Kg. This is the set up you can see Fiona and me using in the Nomad brochure on pages 3 and 15. There is no need to carry too much food but we always carry a whole day’s rations in addition to what we plan to eat that day. When the bikes are set up like this, I believe that they will out handle any racing bike or mountain bike!

Best regards,

Andy B.

Something that really caught my eye as useful and appealing is Andy and Fiona's inclusion of clothing and footwear appropriate to off-bike use and for attending cultural events. If the bike is used for a "balanced holiday" of touring, one doesn't always wish to look like a cyclist off the bike! Touring is *supposed* to be fun; not all wish to Adventure Tour in the most extreme of climates and locales, and even for those who do, the variety of an occasional break in routine is welcome. And nearly everyone will agree...carrying less weight is a whole lot more fun. Besides, a bike designed to handle maximum loads provides an extra margin of security at something less than maximum carriage.

I (Dan) have made some graphics that show how Andy and Fiona distribute the two kinds of loads described above, and attached them below.

Best,

Dan.
« Last Edit: August 10, 2012, 03:49:52 am by Danneaux »

Andre Jute

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Re: Sherpa Shimmy resolved with superb warranty response by Thorn Cycles
« Reply #139 on: August 21, 2012, 09:34:26 am »
What a superb outcome! (See, I told you Thorn would see you right!) Thorn has  fully justified your decision to buy the right bike for you even over the big ocean.

I look forward avidly to your reports of your Nomad in the other threads that will follow, Dan.

We should also take a moment to send a good thought to Robin Thorn and his shareholders, if any, for taking a financial hit by putting the customer first.

Congratulations to all parties on sorting the matter in a civilised, transparent manner -- and turning the whole into a major, truly useful, educational effort.

Andre Jute

StuntPilot

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Re: Sherpa Shimmy resolved with superb warranty response by Thorn Cycles
« Reply #140 on: August 21, 2012, 11:27:53 am »
Dan - a great conclusion and service from the Thorn team! So glad it all worked out well. I knew there were many great reasons to buy a Thorn and this shows yet another when things, on rare occasions, go terribly wrong. Looking forward to more desert touring tales on the new Nomad!  :)

jags

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Re: Sherpa Shimmy resolved with superb warranty response by Thorn Cycles
« Reply #141 on: August 21, 2012, 11:56:37 am »
Fantastic news all round Dan very best of luck with the new bike.
will we be getting any photos of the nomad sure hope so.

Danneaux

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Re: Sherpa Shimmy resolved with superb warranty response by Thorn Cycles
« Reply #142 on: September 18, 2012, 04:31:56 pm »
Hi All!

Thorn followed-up on their outstanding efforts and warranty response to my Sherpa's shimmy problem by having Andy do a complete test ride. Robin wrote me yesterday, saying...

"...Andy tested it last week:

 http://www.youtube.com/watch?v=xNQzNKl8B6E&feature=plcp

 I (like you) no doubt wasn't expecting this to be the result!"

I am as surprised at the result as Robin -- there isn't a single sign of shimmy during Andy's test-ride. Sadly the bike shimmied under me at even a jogging pace with half the load arranged identically -- also while coasting, sitting upright and hands-free like Andy.

Thorn's careful follow through and testing is further sign of their concern for the customer.

Shimmy remains a difficult problem to solve, much less grasp. In my research I have read of bikes that shimmied unusably under one rider and were then sold on to perfectly happy buyers who never had a problem. Similarly, bikes with no problem have developed shimmy with new riders of the same size and mass, and it appears every brand and geometry and size of bike can be affected if the right factors all come into play. The hard part is determining those factors and addressing them. My example is the only Thorn I have known to shimmy, a sign they have a much better handle on avoiding the problem than other makers.

Rivendell's Grant Petersen wrote a short summary of the issues related to shimmy and the difficulty in identifying and resolving the problem in Rivendell Reader 42 ("Early 2010"), reproduced here: http://www.rivbike.com/kb_results.asp?ID=80

Best,

Dan.

JimK

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Re: Sherpa Shimmy resolved with superb warranty response by Thorn Cycles
« Reply #143 on: September 18, 2012, 05:19:03 pm »
This gets me thinking about bicycle black boxes. We already have such amazing tools for tracking physiology... heart rate monitors etc. I wonder what sorts of little mechanical gauges are available to measure e.g. strain at various points around the frame, the rotational position of the steering tube inside the head tube. What about the way the tire is supporting the rim.

One of my nephews has a tricky heart and sometimes they have him carry a little EKG unit around for a few days to try to catch whatever funny business is up at the time.

It doesn't take too much complexity in a system to open up enough territory and enough corners into which freaky behavior can tuck itself and hide. Sure frustrating though!

Did they run this test using your luggage racks? Ah, this is a mystery that is just going to stay a mystery, I fear!

Glad though that your Nomad is pulling through for you!

 

Danneaux

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Re: Sherpa Shimmy resolved with superb warranty response by Thorn Cycles
« Reply #144 on: September 18, 2012, 05:48:05 pm »
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...Did they run this test using your luggage racks?...

Hi Jim! Nope. I had been running the Surly Nice Rack (rear) on the Sherpa and I kept my (separately purchased) Throrn Low-Loader MkV pannier racks for use on the Nomad.

It is possible something there was amiss, but fitting the Thorn EXP rack to the rear of the Sherpa didn't help, and the same Low-Loader MkV racks on the Nomad has made no difference on it. While it is arguable I could try the Surly rear rack on the Nomad, I don't want to tempt fate! Andy Blance has done a very nice job designing the EXP rack and it works extremely well in practice, so I am inclined to leave well enough alone...even for physics!

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Glad though that your Nomad is pulling through for you!

Thank you Jim; me too! The Sherpa was a lovely bike I loved dearly, but did not work for me. The Nomad is also a lovely bike, and works like a champ in the same conditions with the same loads. Similar geometry overall, but heavier tubing or perhaps the greater top tube slope/longer top tube/shorter seat tube/trussed and longer fork may have changed the resonance with my body/position/whatever. Though very similar in many ways, the bikes are also very different in some key ways that might matter. Or not. I think someday, real-time finite-element analysis may give us the definitive answers we seek when approaching the question of shimmy and its causes/cures.

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Ah, this is a mystery that is just going to stay a mystery, I fear!

I think you're right, Jim.

All the best,

Dan.

JWestland

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Re: Sherpa Shimmy resolved with superb warranty response by Thorn Cycles
« Reply #145 on: September 19, 2012, 02:19:53 pm »
We were all expecting a fault with the bike/racks but maybe you have special powers that make bikes shimmy as a side effect  ;D

But it just gets to show Thorn quality control is spot on, and so is the warranty :)
Pedal to the metal! Wind, rain, hills, braking power permitting ;)

triaesthete

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Re: Sherpa Shimmy resolved with superb warranty response by Thorn Cycles
« Reply #146 on: September 19, 2012, 05:02:58 pm »
It was the ultra high frequency cerebral wave oscillations that did it  ;D

Ian

wildrover

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Re: Sherpa Shimmy resolved with superb warranty response by Thorn Cycles
« Reply #147 on: September 19, 2012, 08:48:07 pm »
Similar geometry overall, but heavier tubing or perhaps the greater top tube slope/longer top tube/shorter seat tube/trussed and longer fork may have changed the resonance with my body/position/whatever.

Then do you still need the seat tube with the extra setback?  Did Andy test with that?  Such a mystery!

Danneaux

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Re: Sherpa Shimmy resolved with superb warranty response by Thorn Cycles
« Reply #148 on: September 20, 2012, 06:50:11 pm »
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do you still need the seat tube with the extra setback? Did Andy test with that?

Hi Holly!  

<nods> Yes, I still need the long-layback seatpost to get the proper position in relation to the bottom bracket (the seat tube angles on the Sherpa and Nomad are similar).

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Such a mystery!

It has me baffled!

Best,

Dan.

il padrone

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Re: Sherpa Shimmy resolved with superb warranty response by Thorn Cycles
« Reply #149 on: October 06, 2012, 01:00:15 pm »
Photos, reports, etc of the new Nomad  ??



[edit] Ah, just found your thread in the Member's Gallery that I have missed while out in the wilds of the Red Centre. Cool bike set-up.
« Last Edit: October 06, 2012, 01:03:23 pm by il padrone »