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  • SuDiBe Tandemseiten - Literatur
    thirty years of enthusiastic cycling I ve only hit my head once a solo mountain biking endo that shattered my Giro in the same span of years I ve successfully used maximum braking to avoid a number of serious accidents mostly cars turning across my path And while not wearing a helmet may increase your odds of visiting the hospital if you can t decelerate quickly enough to avoid an accident while riding a tandem you ll put yourself AND YOUR STOKER in the emergency room So how do you learn effective tandem emergency braking As others have already surmised from learning to effectively stop a motorcycle or even a car with ABS braking if you want to stop short of having an accident you ll need adequate tandem specific practice Materials Your tandem a pair of tires you want to replace anyhow a good floor pump tire irons a big empty parking lot one with a 2 3 incline is best a stoker that is as heavy energetic and fearless as you are insert Tim Allen grunting sounds here and two hours when your regular stoker would prefer to be elsewhere Actually your best training partner will be another tandem captain willing to share the cost of a new pair of tires Why the floor pump and tire irons Because of rim irregularities most skids will occur along one section of the tire During your practice session you ll need to occasionally mark and rotate the tire on the same rim to keep from wearing a hole through it First lesson mastering the rear wheel skid Use the downslope to reach 25 mph before using the rear brake only to lay down a long skid mark Note that when the rear tire skids the tandem s wheelbase and lack of front braking keeps the bike from sluing sideways The rear wheel should skid readily it doesn t count if the tandem is already halfway stopped before the rear brake develops enough grip to slide the tire Further because it s easier to skid the rear tire when you apply both brakes together using the rear brake by itself is the only way to properly judge its effectivenees Next is to learn to modulate your braking at the limit of rear tire adhesion Keep practicing until you can leave three successive yard long skid marks Lesson two mastering the front wheel skid Psyche yourself up a bit this next part is scary Remember a tandem with an adult stoker will skid instead of flip In years of playing this game I ve never seen a captain skid their front tire on a first attempt Actually this is just as well At a degree of front brake application below the amount that will cause a skid the front fork becomes very active As you learn to apply the front brake harder tandems with inadequate forks can buck like a bronco How far can a fork flex On cheap tandems and tandems

    Original URL path: http://www.sudibe.de/articles/emergency_stops.html (2016-02-09)
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  • SuDiBe Tandemseiten - Literatur
    a 25 mile round trip from home to join the L A Wheelmen for their medium 40 mile route through central Orange County It was a hot day turnout was low and when nobody wanted to do the 40 we decided to go for the 55 miler As we rode up our driveway late that afternoon we d done 80 miles all in city traffic on a hot day Jan and I were toasted When I opened the garage door to park the triplet Pam ran in retrieved her 16 BMX bike and raced off down the block to visit some friends When we first started experimenting with child stoker kits in the mid 70s we played with both independent coasting and or differentially sized chainrings to lower a child s cadence Both features were scrapped when we learned children with scaled down cranks can maintain 110 RPM longer than their parents While independent coasting seemed like a necessity the noise of the clicking drove parents crazy While many have questioned the stability of a triplet or the ease of captaining one it is easier to ride a well designed triplet than it is to ride a tandem pulling a traditional trailer Both options are more stable than tandeming with a trailabike While Burley s Piccolo is a better solution than the cheaper seatpost mounted trailabikes a child who doesn t lean with the team will negatively affect handling Because the child s center of gravity is behind the rear axle with either a trailabike or a traditional over the rear wheel childseat children in either of these positions can destabilize a bike far more easily than a child riding in a normal stoking position So while all your options have advantages and disadvantages a triplet s only disadvantage is price For the past half dozen years we ve been watching a growing trend where parents buy the triplet soon after their child is born Step one family cycling with a weeks old infant A rear facing automobile infant child seat is firmly affixed between the center seatpost and handlebars Dad controls the bike while mom stokes and entertains the infant This is safer more comfortable and faster than a tandem and child trailer Step two family cycling with a two year old The triplet is equipped with both an over the rear wheel childseat and a central child stoker setup with 3 4 crankarms Both positions feature a harness Because mom is behind and watching children can safely stoke a triplet 12 months before they can be trusted to stoke a tandem at 24 months of age instead 36 Because nap times come frequently when they get tired a young child is simply rotated to the child seat Step three family cycling with a four year old By the time they reach the age of four the child s crankarms can be lengthened by an inch the harness can be removed and the unused childseat can be jettisoned Step

    Original URL path: http://www.sudibe.de/articles/children.html (2016-02-09)
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  • SuDiBe Tandemseiten - Literatur
    enough for tandems customers need to take special care when installing or repairing these chains There are actually three broad generations of chain technology I ll call them pre HG before the advent of ramped cogs HG today s 7 8 cog chain PLUS the original 9 speed chain HG 9 today s 9 speed chain with mushroomed pins The pre HG chain used relatively loose pins that extended beyond the edge of the outer plates The loose fitting pins were easy to install and allowed users to remove and replace pins for cleaning or splicing Relatively idiot proof The advent of HG HyperGlide ramped cogs created unanticipated chain pry apart problems The chain makers responded with tight pin technology The resulting chain was strong on the reel chain is made in a continuous length but had a weak spot where the pin was pushed out for sizing and then re inserted during installation Depending on the quality of the tool and operator the pry apart strength of the spliced link was cut by no less than 10 a trained operator using a pneumatic tool to as much as 40 an average Joe with a hand held chain tool To help solve this problem Sachs KMC and Shimano developed special installation links Trouble is some people even bike shop mechanics ignore these installation links and splice chains together the old fashioned way The result especially on tandems and mountain bikes is a high incidence of chain failure As if one weak spot created during installation wasn t bad enough some enthusiasts will split a chain to remove and clean it and create a new weak spot in the process Or they ll install a larger cog or chainring and splice in additional links and two more weak spots Still because

    Original URL path: http://www.sudibe.de/articles/ninecogs.html (2016-02-09)
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  • SuDiBe Tandemseiten - Literatur
    had never had any of his forks failure tested Second he declined to provide forks for independent lab testing Santana recently purchased and tested a current sample of the fork that AME claims is strong enough for tandems The results were unimpressive even by accepted single bike standards The October 8 issue Velo News reported that the steerer of an Alpha Q cyclocross fork pulled apart while being evaluated on a single bike A photo of the failed fork accompanies the review Personally I would not ride a tandem with an Alpha Q fork Hopefully the new owners of AME Mr Lee sold his company at the end of September will test and improve their product As for testing Reynolds Composites the California fork company not the British tubing company has never released a new fork until after they have destroyed 18 production samples Their internal protocol uses 70 more force and five times as many cycles as the international voluntary test standard that some fork builders don t even bother to use In addition to fatigue testing Reynolds also employs impact tests dropping a heavy weight on a dummy axle and yield tests applying increasing force through a hydraulic piston until the fork breaks Every carbon fork built by Reynolds is considerably stronger than a premium steel fork The new Reynolds carbon tandem fork is considerably stronger than a Santana steel fork An earlier post surmised that the weight of a carbon fiber fork might indicate its strength While this is generally true for steel forks Reynolds who has tested the popular carbon forks from over a dozen various manufacturers reports that the strength of equal weight carbon fiber forks can vary by a factor of four Reynolds new tandem fork is roughly twice as strong as their best single fork at a weight penalty of 100g a quarter of a pound How can a fork be twice as strong without being twice as heavy Instead of achieving doubled strength through additional plies of material the Reynolds tandem fork instead uses larger diameters especially the steerer tube 1 1 4 vs 1 1 8 a fork s all important fulcrum point To achieve this degree of strength without a tandem sized steerer would require an extra 200 300 grams of material One of the various carbon forks Santana tested a beefy looking unbranded cyclocross fork with a 1 1 8 steerer weighed 50 more than the new Reynolds fork and yet was not strong enough to meet our standards It is not surprising to me that the lightest tandem specific carbon fork with a 1 1 8 steerer built by Wound up weighs 900 grams If anyone tries to sell you a lighter 1 1 8 tandem fork you should be suspicious How much weight can tandem enthusiasts save with a carbon fork Tandem specific forks built from steel weigh about 1100 grams The Reynolds tandem fork with its evolution sized steerer weighs just over 500 grams In that

    Original URL path: http://www.sudibe.de/articles/carbonforks.html (2016-02-09)
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  • SuDiBe Tandemseiten - Literatur
    has been successful to the degree that wheel reliability became acceptable the resulting wheels are on average approximately 30 40 weaker than a 160mm wheel built with the same rim and spokes Ultra performance tandem wheels By 1996 a drop in warranty claims verified the incredible strength of 160mm and allowed us to consider radically lighter tandem wheels with fewer than 40 spokes While 36 spokes was an obvious choice our index pointed us to 32 We worked with Zipp and were disappointed to discover that light 32 hole rims cannot tolerate the higher spoke tensions required by tandems With the spokes properly tensioned the front rim would eventually distort into a wavy series of S bends that prevented smooth braking At a subsequent Eurobike Santana s favorite bike show I met Rolf Dietrich who was showing his original sets of paired spoke wheels I immediately realized paired spokes was the breakthrough that would allow tandems to use lighter rims with fewer spokes A few other people noticed those wheels too The next time I contacted Rolf he was contracted to Trek Nevertheless we later met and discussed the co development of Rolf tandem wheels with lightweight rims and 28 spokes Before Santana could supply Rolf with the sample hubs he requested however I was invited to an exclusive unveiling of Shimano s prototype 16 spoke wheels While many enthusiasts assume that all brands of paired spoke wheels have a comparable level of performance those with a clear understanding of spoke bracing immediately knew Shimano s cross over lacing had leapfrogged Rolf s efforts The day of that industry only preview I sat down to lunch with Shimano s product engineers and proposed a 24 spoke 160mm dishless version of their wheelset that would be suitable for tandems While they were excited we imagined the small size of the project would cause Shimano to prefer to license their wheel design to Santana who would produce wheels in the U S A A year earlier Santana had obtained a Shimano s first outside license to produce splined bottom brackets Because Shimano s engineers had a long backlog of projects Santana would need to develop our own prototypes Development and Testing Using only a photo of Shimano s still unannounced 16 spoke wheels Santana worked with Mike Hadley to create sample sets of tandem wheels with Shimano s unique lateral crossover lacing for testing and evaluation When we brought them to Interbike Shimano politely asked us to hide them away The reason Because Interbike was the first opportunity for dealers and the press to inspect Shimano s first ever wheelset that had already won Tour de France stages and the Polka Dot jersey for the best overall climber they hoped we wouldn t wish to diminish the impact of their debut We quickly agreed Except for dealers who saw them during the first hour of show the only attendees to inspect our wheels was a constant stream of Shimano employees who were

    Original URL path: http://www.sudibe.de/articles/tandemwheels.html (2016-02-09)
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  • SuDiBe Tandemseiten - Literatur
    compare our new carbon Beyond with previous exotic frames built by Santana Seven and Calfee the numerous advantages of IsoGrid and Bi Fusion technologies are undeniable For instance when weighed on an accurate scale the Beyond frame is at least 15 lighter than the lightest previous carbon frames and 20 lighter than our titanium frames When stressed on a precision testing jig the Beyond is stiffer than the stiffest frames built from steel or aluminum And beneath our testers delicate derrieres the Beyond is supremely comfortable most have rated it twice as comfortable as the tandem they currently own Mark again Very cool technology but I m still waiting to see the cost My reply 9695 will get you a uniquely efficient and comfortable sub 30 pound tandem with a lifetime frame warranty and proven components Gram shavers and competitors will be able to wring out an additional five pounds Either way you cannot buy a faster and lighter tandem at any price PS Because tandeming is a reliable indicator of an evolved lifestyle spending more signifies advanced intelligence PPS Your neighbors already think you re crazy Why not confirm it Some who responded to last weeks posts have questioned the effectiveness of the IsoGrid internal reinforcement the strength and stiffness of the molded tubes or the accuracy of the build process These are the same tough questions I asked before investing in this new project Why did Santana jump at this opportunity In the last post I explained that Santana had researched and rejected the three previous methods of carbon frame construction The reason I proceeded with this project is that five months of research convinced me that this technology will allow Santana to produce tandem frames with unprecedented levels of performance I ll let Craig explain Carbonframes gussetted process With that exception builders have either glued plain gauge tubes into lugs or molded a one piece monocoque Before someone nitpicks Yes I realize some companies combine both methods by gluing partial monocoques While monocoque forks have set new standards one piece frames have not yet lived up to their still enormous promise Until monocoque frame construction comes of age experiments are incredibly expensive each size specific mold for a single bike costs 8 10 000 and each immutable tandem mold will be 3x as expensive If a builder pursues a non monocoque direction the problem with all other carbon fiber designs including Calfee s and Santana s is the weight of the resulting overlaps and or joints With metal frames steel aluminum or titanium the connection weight of a lugless TIG welded frame is less than 1 of the weight of the frame The connection weight of a composite frame is many times higher In short while carbon is supremely efficient between joints it is woefully inefficient where connections exist Which explains why substituting a lightweight carbon fiber rear triangle to an aluminum or titanium frame actually makes it heavier Though the shiny titanium sections of a Bi Fusion frame may look heavy the co molded tips dramatically reduce connection weight by allowing carbon tubes to be welded directly to each other A number of people have asked to know the exact weight The latest Beyond prototype displayed at Interbike weighed 5 71 pounds complete with paint and all welded fittings in a MEDIUM size suitable for captains from 5 10 through 6 When compared against other painted frames in the same size the still heavy prototype is more than a pound lighter than any carbon frame I m aware of two pounds lighter than a medium frame built from the lightest Easton aluminum tandem tubeset and four pounds lighter than a Cannondale frame PS When will the Beyond reach production Now that our new frame jig and proprietary molds are finished one final hurdle exists before production is scheduled Next week an independent lab will pull apart some Bi Fusion tubes with various length overlaps to determine the correct length for the ti sections which are currently too long We ll also pull apart some same diameter Easton tubes to make sure our carbon Beyond remains stronger than our current aluminum frames While shorter ti sections won t get the weight under five pounds I am confident that 2 50kg 5 5 pounds is a realistic projection for a medium size painted frame with all welded fittings PPS Is weight the primary goal Hardly Every test rider so far has rated our current Beyond prototype both stiffer and more comfortable than any tandem frame they have previously ridden While weight is the easiest way to compare tandem performance I would argue that stiffness and comfort are better indicators of real world performance and owner satisfaction If you are an experienced tandem team and will visit Southern California this winter call our test ride line at 909 596 7570 ext 10 and leave a message with your names phone number and current tandem A post and apology from Bill at Santana While Craig Calfee and I would undoubtedly rather eat chocolate than quibble over definitions he correctly noted that my claim about Serotta s Ottrot carbon titanium frame was wrong The Ottrot DOES include Ben s inspired conically tapered downtube design Although our sport loves tubing with funny shapes most of the claims about these shapes are bogus Serotta s efficient Colorado Concept conically tapered downtubes on the other hand are a proven way to increase a frame s efficiency Sorry Ben I want to thank Calfee for his informative reply Craig certainly has more experience with carbon than I Additionally while most carbon frames intro d in the 80s are now obsolete the gussetted design used by Carbonframes Calfee has established an enviable track record Incidentally my bike shop was one of Carbonframes first dealers and Santana met and consulted with Craig s partner Steve Levin in 1992 to explore the idea of licensing their Carbonframes technology to produce a Santana carbon tandem I hope Craig does

    Original URL path: http://www.sudibe.de/articles/carbontandems.html (2016-02-09)
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  • SuDiBe Tandemseiten - Literatur
    Avid s just introduced Juicy hydraulic looks very promising for single bikes Part 4 Cannondale s disc brake testing Two years ago Cannondale s Testing Engineer Mark La Plante designed a tandem specific lab test to simulate a descent of New Hampshire s Mount Washington home of an annual bicycle challenge After every disc Cannondale tested failed this test they cut their tandem brake standard in half Instead of applying the lever to achieve 60 foot pounds of braking force with their new test the brake lever would be squeezed half as hard in order to create 30 foot pounds of braking force Still 30 minutes long they call their new test Half Mt Washington To put the 30 and 60 foot pound figures in perspective a strong squeeze of a brake lever can create more than 120 foot pounds of braking force When I asked Mark La Plante why Cannondale had decided to make their test twice as easy his reply was that without this change Magura s tandem approved Gustav M could not pass While the original Mt Washington test may have been a reasonable real world standard Cannondale was reluctant to fail a certified brake from a respected manufacturer By cutting their test in half the Gustav M could pass Once the bar was lowered Magura s Julie also passed And if Cannondale relaxed their standard a bit further by allowing the test to be paused for pad readjustment Avid s largest 8 203mm disc could also pass I then contacted Buck Mitchell from Magura USA to purchase a 3rd generation Gustav M and to ask about their tandem approved rating When the answer arrived from Germany I learned that Magura tests brakes for both power and heat To pass their tandem specific heat test a brake needs to produce 1000 watts of stopping power for 15 continuous minutes without boiling fluid or suffering from excessive fade And after cooling it needs to repeat this performance without needing readjustment or using up more than 30 of its pads Here is a quick summary of tandem specific disc testing Santana 15 grade for 2 3rds of a mile Cannondale 30 foot pounds of braking force for 30 minutes Magura 1000 watts for two tests of 15 minutes each Hayes Subscribes to Santana s test Hope and Shimano No tandem specific test standard Avid No testing whatsoever PS It is interesting to me that Cannondale s reason for cutting their original tandem test standard by 50 was to let a respected Magura disc pass But then in order to also pass an Avid disc Cannondale watered down its 50 standard to allow a mid test readjustment a fudge that is not allowed by Magura s test standards PPS Watered down testing reminds me of two years spent on a local school board If you can t get students to pass the tests are too hard Part 5 Avid denies tandem certified and Cannondale works on a new tandem disc test After Avid reportedly changed their long standing prohibition on installing their disc brakes on tandems I gave them a call Instead of a design change or test data however Avid referred us to Da Vinci and Cannondale for their test results Instead of a test Da Vinci s Todd Shusterman related a successful tandem descent of Mount Ventoux 13 miles averaging 7 5 Cannondale s initial test was a simulation of Mount Washington 7 6 miles averaging 12 When the Avid brake failed this test Cannondale cut the required braking force from 60 foot pounds to 30 foot pounds When the Avid disc failed the Half Mount Washington test Cannondale amended the protocol a second time to allow a pause for readjustment Based on passing this third version of a tandem specific test Cannondale s Product Managers were allowed publish a tandem specification that included Avid discs In the meantime Cannondale s Testing Department was unaware of Avid s still in place ban on tandem disc installation Because Santana had not yet tested the newest 8 inch 203mm version of Avid s not for tandems brake in September we scheduled a retest to see if Avid s biggest brake would survive Mountain Avenue 2 3 of a mile averaging 15 In case you ve forgotten three brakes have passed our six year old test a standard Arai drum and two tandem specific discs from Formula 185mm and 203mm When tested Avid s 8 disc failed after one half mile As is sometimes the case this test was a double failure the brake could not maintain the 15mph test speed excessive fade and was disabled in the process melted adjustment fittings Instead of moving the finish line we decided to mate a second Avid caliper the first one could no longer be adjusted with a prototype 10 rotor Unfortunately at the half mile point the Avid again experienced runaway fade Then before the tandem could be brought to a stop our prototype 10 inch rotor warped We later learned that our prototype a show only dimensional sample hadn t been heat treated Because the adjustment pieces again melted this test was a rare triple failure warped non Avid disc excessive fade and melted pieces When I visited Avid s Interbike booth two weeks later Paul Kantor was not surprised by the failures He then reminded me that Avid has never certified the brake for tandem use Surprised by his remark I asked for clarification Kantor replied that with tandem builders such as Da Vinci and Cannondale ignoring Avid s ban and performing their own tests Avid has decided to abandon their former position and will let builders dealers and customers make their own decision Avid s only change Kantor continued was to take no official position on tandem use Kantor then directed me their current OEM product sheet and expo signage While recommended uses for Avid s mechanical discs include cyclo cross touring and recumbents the word TANDEM does not

    Original URL path: http://www.sudibe.de/articles/billondiscbrakes.html (2016-02-09)
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  • SuDiBe Tandemseiten - Literatur
    popularized in France sixty years ago tandems built with this simple and inexpensive design include those by Rene Herse and Alex Singer Dormant for decades the open frame was revived in the U S twenty years ago by John Slawta under the trade name Landshark While Herse Singer and Slawta were are highly respected artisans the performance of their beautiful open tandems was dreadful I have not only personally ridden examples of all three frames I ve also personally sold new tandems to owners of these brands who desired frames with greater performance Did Bruni copy these older French and American designs Tom s contribution to the previously discarded open design was the use of larger diameter top bottom and down tubes in the belief that these larger and stiffer tubes would make laterals redundant Unfortunately Tom a brilliant designer and craftsman that I shared a number of long discussions with never had the means to verify this theory through scientific or direct comparison testing Other tandems lacking laterals designs totally different than those of Herse Singer Slawta or Bruni are frames of exceedingly small stature In this group I include Bike Friday s Two sday and Co Motion s Periscope What these smaller open frames have in common is that there isn t much room between their top and bottom tubes Finally all these former designs are quite different from a new fashion in superlight tandem frames that has captured Rudy s attention In comparison to these newest open frames Bruni s open frame was according to Tom an attempt to balance framebuilding costs with performance Tom simply thought it more effective to re invest the weight of the laterals in larger diameter top bottom and down tubes While Bruni frames were lovingly built and beautiful to behold Tom never claimed that they were particularly light The newest versions of the open design all appearing in the last year are born of the desire to build a tandem frame as light as Santana s 3 year old Beyond with IsoGrid weldable carbon tubing When introduced at 5 5 pounds in a medium frame size the IsoGrid Beyond was a pound lighter than a same sized Calfee or Zona A fourth contender in the sub 6 category is the magnesium framed Paketa The only way these others have been able to join Santana in the sub 6 category was to shed a pair of lateral tubes If Santana were to build an IsoGrid Beyond without laterals the weight in a medium size could be 4 5 pounds lighter than the lightest Calfee Zona or Paketa When will Santana do this Don t hold your breath Unlike those other builders Santana commissioned the electronic strain gauge testing that used real frames and strong riders to scientifically confirm the contribution of lateral tubes to the pedaling efficiency of a tandem frame We have also shared design information with three companies that computer modeled the pedaling efficiency of various tandem frame designs All

    Original URL path: http://www.sudibe.de/articles/billonopenframes.html (2016-02-09)
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