Without further information or context, it is difficult to determine if the bike gear is broken. It would be helpful to inspect the gear system, listen for any unusual noises while cycling, and test the gear shifting functionality to determine if there is an issue. If there are any visible damages or if the gears are not shifting smoothly, it is possible that the bike gear is broken and may require repair or replacement. **

The racing bike gear system is typically found on racing bikes, also known as road bikes. These bikes are designed for speed and efficiency on paved roads, and the gear system is essential for riders to adjust their pedaling resistance and maintain an optimal cadence. The gear system on racing bikes is often lightweight and designed for quick, precise shifting to accommodate the fast-paced nature of road cycling. **

The bike gear is shifting to allow the rider to maintain an optimal pedaling cadence and power output based on the terrain and riding conditions. By shifting gears, the rider can adjust the resistance on the pedals, making it easier to pedal uphill or allowing for faster speeds on flat terrain. Proper gear shifting also helps to prevent muscle fatigue and improve overall efficiency while riding. **

Going on bike tours with a fixed-gear bike requires some preparation and consideration. First, it's important to ensure that the bike is properly fitted and adjusted for long-distance riding. This may include adding a front brake for safety, as well as choosing the appropriate gear ratio for the terrain. Additionally, packing light and efficiently is crucial, as fixed-gear bikes lack the gear range of multi-speed bikes. It's also important to be mindful of the physical demands of riding a fixed-gear bike for long distances, as it requires more effort to climb hills and can put additional strain on the knees. **

For a small man, a suitable adventure bike would be one with a lower seat height and a more manageable weight. Bikes like the Honda CRF300L, Kawasaki Versys-X 300, or the Suzuki V-Strom 250 are good options as they have lower seat heights and are lighter, making them easier to handle for smaller riders. It's important for a smaller rider to be able to comfortably reach the ground and have control over the bike's weight, so these factors should be taken into consideration when choosing an adventure bike. **

Without further information or inspection, it is difficult to determine if the gear shift on the bike is broken. Some signs that the gear shift may be broken include difficulty shifting gears, unusual noises when shifting, or visible damage to the gear shift mechanism. It is recommended to have a professional bike mechanic inspect the gear shift to determine if it is broken and needs repair or replacement. **

The rear bike gear shifting system works by using a derailleur to move the chain between different sized sprockets on the rear wheel. When the rider shifts gears using the shifter on the handlebars, the derailleur moves the chain to a different sprocket, changing the gear ratio. This allows the rider to adjust the resistance and speed of pedaling to match the terrain they are riding on. The rear gears are typically controlled by the right-hand shifter on the handlebars, with each click of the shifter moving the chain to a different gear. **

On a regular mountain bike, the gear that corresponds to that of a regular BMX bike would be the middle gear. This gear provides a good balance between speed and power, similar to the gear typically used on a BMX bike for general riding and tricks. It allows for efficient pedaling while still providing enough resistance for acceleration and control. **