In developing our bikes, we always employ the principles of simplicity and quality to offer the best experience for each application. For urban use and shorter journeys, in less rugged areas we have our line of Singlespeeds.
But what is the solution for longer journeys in more pronounced relief or even for those who want more comfort? If you've thought about a bike with gears, you've got it right. But it couldn't be any change. We wanted to preserve the advantages of a Singlespeed bike, such as high efficiency, low maintenance, less risk of getting in the way due to breakage and at the same time offer more transmission ratios (gears). All this without complicating the experience of riding a RIVA and above all preserving our principles of minimalist design, discreet and without pendants. Solution: IGH (Internal Gear Hug) or internal hub gear system.
Ao contrário dos sistemas de câmbio com descarrilador (ou Derrailleur), onde as engrenagens e o mecanismo ficam expostos, um Câmbio IGH é um sistema de mudança de marchas com engrenagens planetárias ou epicíclicas, similares no conceito ao que vemos em partes de alguns sistemas de transmissão automotivos. Em resumo, é como se todas aquelas rodas dentadas enfileiradas, tensionadores e passadores fossem compactados de forma engenhosa dentro do cubo traseiro da bicicleta.
Long life
As engrenagens e os lubrificantes são vedados dentro da carcaça do cubo, um sistema blindado, por isso, é um sistema praticamente livre de manutenção e são mais confiáveis ao longo do tempo do que os sistemas de câmbio com descarrilador comum, que podem exigir mais ajustes e substituição de peças (coroas dianteiras, pinhões traseiros, corrente, por exemplo ). Um chainline único não exige que a corrente se dobre ou torça. O contato da linha entre as superfícies dos rolamentos, em vez do contato pontual de uma corrente descarrilador, aumenta muito a vida útil de todos os componentes.
How to use
Uncomplicated use of gears in the city - Conventional IGH is also simpler to use, because there is only one shift mechanism to operate and there are no overlapping transmission ratios, unlike gear shift models with external derailleur that usually have two shift levers on the handlebar (one on each side) and require a bit of reflection to avoid problematic combinations of gears or derailment (fall) of the chain. On IGH it's simple: up, light gear, down, more speed!
With the IGH you can change the ratios (change gear) when the rear wheel is not turning. This can be useful for cycling with frequent stops, such as at traffic lights, pedestrian lanes or junctions. It does not require that uncomfortable pedalling when resuming movement to turn until the gear is changed, always with a ˜crack crack˜ and with risk of chain fall.
Consequences for the bike construction
A roda dentada externa única significa que a roda pode ter um cubo com mais distância entre suas flanges e ser construída de forma mais simétrica com pouco ou muito menos “ chapéu”, tornando-a lateralmente mais forte do que uma roda similar com espaçamento mais estreito da flange e mais “chapéu” para acomodar várias rodas dentadas. Além disso, para oferecer a possibilidade de uso de correia (no lugar da corrente), que vem se revelando uma tendência para bikes de baixíssima manutenção, é necessário construir o quadro com uma abertura para permitir a montagem da correia na bicicleta, já que correia não pode ser segmentada.
IGH systems generally have a long and virtually maintenance-free service life. They are commonly found in versions ranging from 2 to 14 gears. An IGH gearbox also allows the use of transmissions compatible with belt drives or cardan shaft drives.
Specs
The model used by RIVA in its urban bikes is the Sturmey Archer RS-RK3, with the housing made out of aluminum 6061.
- 3 speeds with a wide transmission ratio of 177%
- 33% and 33% marching steps
- Compatible with 17 to 19 tooth pinion
- Anodised finish
- Weight - 1095g
Gear ratios
- Total range - 177%
- First gear - 75% (second gear - 25%)
- Second March - 100% (direct drive)
- Third march -133% (second march + 33%)
The Operation
Commonly found in versions ranging from 2 to 14 gears, the choice of the number of speeds is always a compromise between cost, weight (more gears, more weight) and need according to the relief where the bike will be used. To explain the principle of operation, we will use the example of a 3-speed gearbox . The 3-speed hubs usually use a single set of planetary epicyclic gears. The solar gear (in yellow) is mounted solidly on the axle and is therefore fixed in relation to the bike structure.
In low gear, the gear wheel drives the ring (in red above) and the planetary conveyor (in green above) drives the hub, reducing the gear.
In the intermediate gear, the sprocket drives the hub directly.
At high speed, the sprocket drives the planetary conveyor and the ring moves the hub, resulting in an increase in gearing
Most hub gears are operated with a single turn, trigger or gear shift knob. The gears of an IGH gear shift are indexed (as if they were self guided by the gear design itself). In practice, gear shifting and consequent internal damage is unusual, except in high mileage units.
