domingo, 21 de setembro de 2014
terça-feira, 16 de setembro de 2014
Cambio interno, matéria interessante publicada na Revista Bicicleta.
+bicicleta - Entenda Melhor
Câmbio Interno
Revista Bicicleta por Fábio Zander
17/01/2013
Foto: Divulgação
Nos últimos anos se tem feito muito no mercado dos câmbios internos. De oito até, em breve, dezoito velocidades, é possível achar câmbios para todos os tipos de uso e terrenos. O mercado tem lançado periodicamente novos produtos.
Câmbios internos são mais antigos do que os câmbios tradicionais que conhecemos. Até os anos 90, os câmbios internos com poucas velocidades e freios de contra-pedal eram usados apenas em bicicletas urbanas e em passeios curtos por terrenos planos.
Um lançamento em 1998 mexeu com o mercado dos câmbios, principalmente na área domountain biking. O renascimento dos câmbios internos com a inovação Speedhub 500 de 14 velocidades da empresa alemã Rohloff. O lançamento não tirou o domínio dos câmbios tradicionais, mas ofereceu uma nova opção na mudança de marchas.
Muitos usuários dão importância à eficiência mecânica na transmissão total entre a marcha mais leve e a mais pesada. Por exemplo, para os aficcionados em mountain biking, o importante é pedalar bem montanha acima e ter bastante pressão nos pedais morro abaixo, assim necessitam de pelo menos 500% de transmissão.
Quanto menor a diferença na mudança entre duas marchas (aquele “salto” quando mudamos de marcha), menor é a perda de energia durante a pedalada. As fabricantesPinion e Rohloff saem na frente com respectivamente 11,5% e 13,6% para as transmissão entre cada velocidade.
Um pouco de matemática
Como calcular a transmissão total de uma bicicleta
O primeiro passo é calcular a menor e a maior distância percorrida pela bicicleta a cada volta de pedal.
Para calcular a menor e a maior distância, é preciso achar o comprimento da circunferência (Y), que é o resultado da multiplicação do diâmetro da roda (em metros) por pi (3,1416).
Menor distância: Dividir o número de dentes da coroa menor pelo número de dentes do pinhão maior. O resultado dessa divisão, multipica-se por Y e chega-se ao resultado da menor distância.
Maior distância: Dividir o número de dentes da coroa maior pelo número de dentes do pinhão menor. O resultado dessa divisão, multipica-se por Y e chega-se ao resultado da maior distância.
O segundo e último passo é o cálculo de transmissão em porcentagem com a seguinte fórmula: (distância maior / distância menor) X 100.
Como calcular a transmissão entre cada marcha
Já começo com um exemplo para descobrir a transmissão entre um pinhão com 34 dentes e o seu vizinho com 30 dentes. Divida 34 por 30 e o resultado que se chega é 1,133 que também significa 13,3%.
Tabela comparativa entre câmbio tradicional e interno
Abaixo segue um gráfico que compara um câmbio tradicional de 27 velocidades e um câmbio interno Rohloff de 14 velocidades.
Para esse gráfico foi utilizado um conjunto de coroas 24/32/44 e um conjunto de pinhões (cassete) 12-34.
Repare que no caso do câmbio tradicional de 27 velocidades, as marchas em vermelho são repetidas e que na verdade existem apenas 14 velocidades “verdadeiras”.
Informações adicionais para entender a tabela acima.
Câmbio tradicional de MTB
Transmissão = 519 %
Distância percorrida a cada volta do pedal (aro 26”): de 1,45 a 7,55 metros
Câmbio interno Rohloff
Transmissão = 526 %
Distância percorrida a cada volta do pedal (aro 26”): de 1,44 a 7,56 metros
As vantagens do câmbio interno
O que faz o câmbio interno ser tão interessante atualmente?
- O câmbio interno, por ter um “corpo” estanque e protegido contra água e pó, não tem grande desgaste de peças internas. O intervalo das revisões e a troca de corrente é feita a cada 5.000 quilômetros ou uma vez ao ano. Já a corrente sofre bem mais desgaste com a chuva, lama e pó, sendo trocada a cada 2.000 quilômetros, aproximadamente.
- A mudança de marcha com a bicicleta parada não é problema para o câmbio interno. Além disso, por não precisar ter um câmbio do lado esquerdo para trocar marchas na coroa, o ciclista executa todas as mudanças com apenas uma mão.
- Robusto. Não existem peças expostas com risco de serem danificadas, por exemplo, em uma queda.
- A roda traseira é mais estável. Só existe uma catraca para a corrente. Ao contrário dos câmbios traseiros tradicionais em que a corrente trabalha em até 10 catracas e que deixam os raios de um lado quase verticais ao eixo da roda.
O mercado de câmbios internos
Os câmbios internos de série oferecem bons preços para ciclistas urbanos, cicloturistas em curtas viagens e e-bikes. A tendência é que esse mercado dos câmbios internos cresça e a concorrência entre as empresas gere bons produtos e preços mais acessíveis para nós, ciclistas.
domingo, 7 de setembro de 2014
sexta-feira, 5 de setembro de 2014
Lauf Fork
Lauf Fork - avaliação.
recentemente adquiri uma suspensão Islandesa da marca Lauf.
Peso 1Kg, fácil de montar e, segundo o fabricante custo zero de manutenção.
Quero dizer inicialmente a maneira pessoal com que fui tratado e o envio da suspensão de maneira exemplar.
O Lauf Fork foi montado ma minha Niner Air Carbon Tang, peso total com os pedais 10,2Kg.
O nosso grupo, Rugas do Cerrado, faz normalmente estradões de terra, sem single traks, mas com muitas costelas de vaca, descidas e subidas, cascalho solto e areia ou terra fofa.
A avaliação foi em um percurso de 65 Km, com área de descida com cascalho solto e estradão mais plano onde pegamos boa velocidade, mas com algumas erosões na estrada.
A suspensão passa segurança e não me deixou sentir falta da antiga did que estava montada anteriormente.
Aprovada e recomendada.
Lauf Fork - evaluation.celand recently acquired a suspension of Lauf brand .1Kg weight , easy to assemble and , according to the manufacturer cost zero maintenance .I want to first tell the personal way in which I was treated and the sending of the suspension in an exemplary manner .The Lauf Fork was mounted in my Niner Air Carbon Tang , total weight with 10,2Kg pedals .ut with lots of cow ribs , descents and climbs, loose gravel and sand or soft earth . The evaluation was on a journey of 65 km, with an area of descent with loose gravel and dOur group , the Cerrado Wrinkles usually makes dirt roads of land without single traks , birt road where the plane took good speed , but with some erosion on the road. The suspension passes safety and not let me miss the old did that was previously mounted .Approved and recommended .
quinta-feira, 4 de setembro de 2014
Fwd: Competition is Your Oxygen - New Niner AIR 9 Family! Are you ready for Cross Vegas?!
Peça já a sua Niner conosco.
Marcelo C. Daher
Marcelo C. Daher
Infectologista, CRM/GO 7127
Av. São Francisco, 251 bairro Jundiai, Anápolis/GO 75110-810
55 62 33246133
Início da mensagem encaminhada
De: Niner Bikes <info@ninerbikes.com>
Data: 4 de setembro de 2014 13:05:50 BRT
Para: dahermc@hotmail.com
Assunto: Competition is Your Oxygen - New Niner AIR 9 Family! Are you ready for Cross Vegas?!
Responder A: info@ninerbikes.com
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The new Air 9 RDO is a product of almost a decade of refinement and testing, courtesy of Niner's racing and engineering programs. Riders will see the results in everything from the weight, the geometry, the carbon frame design and the technical details.
The Air 9 RDO's sleek carbon frame design benefits from years of Niner engineering development, process improvement and testing - via both Niner's in house test lab and independent resources - it began with our first race bikes in 2005, saw significant changes with the introduction of the first Air 9 RDO in 2012 and culminates in the minimalist and light RDO Carbon Compaction version we've designed for the 2015 racing season.
The Air 9 RDO is beautiful from the inside out via Niner's Carbon Compaction System. Now used throughout the Niner RDO lineup, this CCS utilizes rigid internal molds and results in tighter, more consistent compaction of the carbon layers, yielding increased precision in wall thickness and significantly reduced resin pooling in the final product, allowing us to aim for better ride tuning, increased strength and durability along with the significant weight reduction that results from a more efficient and precise process. Even with the addition of a rear maxle, the Air 9 RDO is over 100 grams lighter (one-quarter of a pound).
The shapes of our Air 9 RDO frame draw from our long history in carbon fiber design - in particular from our experience in building light, strong hardtails with velvet off road ride-quality. The rigid sides of our signature downtube and top tube shapes maximize torsional stiffness, with buttery smooth ride quality achieved via the flat sections on each tube, which act like leaf springs. Chainstay and seatstay shaping also benefits from our years of hardtail expertise - they are one hundred percent designed for weight savings and ride quality via a minimalist carbon layup that, because of our RDO carbon Compaction process, still meets the most rigorous standards for mountain bike safety.
Cross section of the AIR 9 RDO down tube. The flat top and bottom surfaces act as leaf springs and produce the renowned Niner ride quality. The angled sides produce stiffness and efficient power transfer.
Niner's hardtail racing geometry is one that has has garnered multiple national championships via the original Scandium Air 9, a Singlespeed World Championship via the Air 9 Carbon, a Pan American Championship via the One 9 RDO and World Cup podiums and national series race wins via the original Air 9 RDO. Though time tested, Niners geometry has not remained stagnant - it has seen continual refinements to account for new technologies and to accommodate new fork travel lengths, while still meeting EN Safety standards for increased forces. The new Air 9 RDO can safely accommodate forks with up to 120mm of travel, while maintaining the stable, precise steering and handling that lets your relax, be confident and focus on being fast.
The new Air 9 RDO is offered in the full range of Niner size options, from XS through XL. Smaller sizes have adjusted layup for lighter weight and avoid toe overlap.
Our robust R&D program-computer modeling, physical prototype testing (both in-house and at independent testing facilities), and hours of ride testing under highly skilled and abusive test riders leave us confident that the AIR 9 RDO is going to exceed your expectations in both weight and safety categories. We maintain that our carbon fiber testing and design rivals the best in the bike industry, meeting EN (European) standards for safety, even at longer fork travel lengths) We choose to demonstrate this commitment to your well being and to product durability via our C5 warranty (five year) and commitment to exemplary customer service.
The AIR 9 RDO utilizes the Press Fit 30 standard, the larger shell mates beautifully with the larger carbon downtube for elegant looks and efficient power transfer so crucial in a race bike. Additionally, this allows for the use of the stiffer, lighter crankset designs that fit the PF30 standard.
The AIR 9 RDO frame can be paired with any standard taper steerer XC cross country fork from 100-120mm in travel. For the ultimate in light weight short track racing machines, pair it with Niner's RDO Carbon fork. Niner's award winning rigid carbon forks have set the standard for weight, ride quality and safety for years - we've used this experience to create an race fork with the off-road ride quality racers want. Fork stiffness prevents energy robbing brake rub and the thru axle plus taper-steerer combo ensures precision cornering on the toughest of courses.
The AIR 9 RDO frame details benefit from the same iterative process that drives the overall design - the headbage is sleeker and lighter, the cable routing is direct and easy for team mechanics (or privateers) to maintain. Each of these small changes adds up to a huge difference for a rider that wants to keep focus away from maintenance and on the competition.
The Air 9 RDO is available in two finish options, both heavily influenced by the race-specific demands of the model. For the Niner Team livery, we've pared the paint down to the minimum and used a light satin clear coat for a protective layer. The stealth version sees the same treatment, but in an aesthetic best utilized in sneak attacks.
The AIR 9 CARBON features the same sleek carbon frame design as the Air 9 RDO with a slightly simpler layup and material choice. Riders benefit from 10 years of hardtail development, engineering, process improvement and testing without breaking the bank. In this newest version, you'll find increased strength and durability along with the addition of a rear maxle for better descending and cornering.
The AIR 9 CARBON frame details benefit from the same iterative process that drives the overall design - the headbage is sleeker and lighter, the cable routing is direct and easy for team mechanics (or privateers) to maintain. Each of these small changes adds up to a huge difference for a rider that wants to keep focus away from maintenance and on the competition.
Get complete Air 9 Carbon details and pricing here.
The new AIR 9 in hydroformed alloy benefits from the same decade of refinement and testing as does the entire Air 9 family, while representing NIner's most economical racing option. Riders benefit from years of hardtail experience with the unique ride quality of a high end alloy frame.
This version of our alloy hardtail integrates hydroformed tubing throughout. More than a cosmetic feature, hydroforming allows us to shape tubes, control wall thickness and optimize strength and stiffness in key areas. This customization creates perfectly tuned frames with precise ride characteristics - in other words, ideal ride feel. You will find hydroforming in the toptube, downtube, headtube, chainstays and seat stays. Bottom line? A light, stiff frame with better ride feel and improved steering results in better power transfer and an overall efficiency improvement. In other words, the updated Air 9 will win more races.
Niner is commited to producing high-end alloy frames. The shapes of our Air 9 hydroformed frame are heavily influenced by our long history in carbon fiber race frame design - in particular by our experience in building light, strong hardtails with velvet-smooth off road ride-quality. The rigid sides of our signature downtube and top tube shapes maximize torsional stiffness, with buttery smooth ride quality achieved via the flat sections on each tube, which act like leaf springs.
Don't waste your training - a 142x12 spacing combined with a Maxle maximizes an athlete's power transfer via rear triangle stiffness. Maintenance is easier, too - the Air 9 shares same Niner derailleur hanger as many Niner models for easy replacement via your local dealer.
Best paired with Niner's RDO frames, our "spare no expense" 5-Star Builds are filled with top of the line components for the cycling connoisseur or athlete who refuses to compromise.
A careful blend of practicality and passion, 4-Star Builds know where to put the bling and where to get clever when it comes to optimizing performance. Perfect for the privateer racer or anyone who recognizes top-level performance but has bills to pay.
Field a loyal and trusty steed without breaking the bank. Our 3-Star Builds offer the best technical features from each manufacturer with an eye for substance over style. Great for riders who want a sweet bike but know that it's the engine that counts.
A 2-Star Build is designed to get Niner owners out on the trail, happy in the knowledge they got a great bike at a great price. Perfect for riders who desire a taste of how quality components can transform the riding experience.
These introductory builds are lovingly curated to deliver the most bang for the starter buck. The 1-Star Build is a popular choice for new racers and great for a first Niner because it's riding, not frills, that ignites passion for the trail.
Are you heading into your first season of 'cross racing? It is time for more great cyclocross videos from the CLIF team. In the second of a series of five how-to videos (get the first video, on choosing a cross bike, here), professional cyclocross racer Troy Wells talks about tire selection.
In the third how-to cyclocross video from Team CLIF, professional cyclocross racer Troy Wells discusses clothing choice for a variety of weather conditions.
Thanks to New Belgium Brewing for letting us hang out in their famous Tour De Fat workshop and on their cyclocross course for filming. Get more bike checks, technical information and ride stoke on our Vimeo channel or on our YouTube channel. BSB 9 RDO cyclocross bikes are available shops now - only 2 weeks till cross season starts!.
Niner rider and Team Backcountry.com athlete Chloe Woodruff continued her season of domination with a fantastic double at the Grand Junction Off Road last weekend on her XS Jet 9 RDO. Chloe killed the competition in both the Dirt Crit and the 40 mile XC race, winning a couple of nice big checks that will help take her to the world championships in Hafjell, Norway next week!This will be Chloe's first World Champs as an Elite rider - her first Worlds was Les Gets, France in 2004 as a Junior and her last U23 Worlds was in Canberra, Australia in 2009. We could't be happier to have such a great rider and ambassador on our bikes - Best of Luck in Norway, Chloe!
Though few would expect Miami to have quality singletrack, the area plays host to four mountain bike parks and miles of trail. Niner has found a great dealer in this corner of the cycling world with shop owner Arnie Freire and Bike Tech USA.
With three locations, Florida-based Niner riders have several opportunities to view the latest and greatest offerings. The east Miami location has the largest selection of mountain bikes, due to its proximity to the Virginia Key mountain bike trails, but all locations carry a solid lineup of Niner gear and bikes on the floor to drool over.
Bike Tech USA comes to mountain biking ready to play ball. Finding value in the big wheels for local riding, the strong grassroots presence and small company feel all hold a strong appeal. However, it is the focus on big wheels and the aplomb with which Niners handle the sandy, rock-strewn singletrack that make Niner a strong choice for Florida riders.
Head in and check out the new shop and have the crew at Bike Tech get you setup for the season ahead.
Find Bike Tech at: biketechusa.com or like them on Facebook to stay connected for community and events.
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Niner Bikes
877-646-3792
Niner Bikes | 1611 S. College Ave Suite 202 | Fort Collins | CO | 80525
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