TPU tubes are gaining attention as the third force in bicycle tires. We summarize its features, advantages and disadvantages of using it on road bikes and MTBs, and major manufacturers.
Table of contents
Main Number of Shifts on Road Bikes
Number of Shifts for Shimano Road Bike Components
Shimano components for road bikes have a maximum of 3 front and 12 rear gears. The number of gear shifts is determined by which grade of component you use.
The number of gear shifts for the current and one previous grade of road component is as follows.
Number of speeds in Campagnolo’s road bike components
The current line of road bike components from Italian bicycle parts maker Campagnolo all have at least 12 speeds in the rear, with the exception of the CENTAUR, and the EKAR, which is designed for gravel, has 13 speeds in the rear.
Number of Shifting Gears in SRAM’s Road Bike Components
American bicycle parts manufacturer SRAM’s road bike components feature a wide range of gear shift options in the higher grades, as the company also offers a front single-component lineup in line with recent trends.
SRAM’s XPLR gravel component is not a stand-alone component but a front single when combined with Red, Force, or Rival.
Advantages of Increasing the Number of Gearshifts
Easier fine tuning at cruising speeds
The biggest advantage of having more gears is that it allows for fine adjustments at cruising speeds because there is less difference in the top gear.
For example, if you are cruising at a speed of 30 km/h, and you feel the need to “rest your legs a little” when there is a headwind or a 2% gradient, the gear ratio will drop by about 0.3 if you have a small number of gears, and the speed will drop by about 3 km/h to 27 km/h if you continue at the same cadence. On the other hand, if the speed is reduced to 11 or 12 gears, the speed will drop to 27 km/h.
On the other hand, if there are more rear gears, such as 11 or 12 speeds, the top 5 or so gears have a 1 tooth difference, so the speed difference at the same cadence is only 1 km, or 29 km per hour.
When riding on suburban roads or bike paths with few traffic signals, there are times when you want to “maintain speed as much as possible while resting your legs a little,” so this is effective in such situations.
The low side can be widened.
If you keep the gear ratio in the cruising speed range in a cross ratio, the maximum gear on the low side will inevitably be smaller.
However, if the number of shifting stages is small, widening the low side will increase the gear difference on the top side, sacrificing fine adjustment at cruising speeds.
If the number of shifting stages is large, even if the low side is widened, the top side can be configured with a certain amount of tooth difference, allowing for a wide range of roads to be covered.
There are more choices in the front end.
Since the gear ratio of a road bike is based on the denominator of the number of teeth in the front chainring, the front choices have a large impact on the overall gear ratio of the bike.
When riding on hills such as hill climbs with a small number of shifting gears, it is often necessary to use a compact crank such as 50-34T for the front chainring to lower the overall gear ratio.
However, if rear shifting is more common, widening the low side (32T for 11-speed, 34T for 12-speed) is an option, so you can take measures against hills even if you keep the front chainring on a normal crank such as 52-36T. Moreover, if you use 11-speed or higher, even if you widen the low side, the top side will have about 4 teeth difference of 1, so you don’t have to kill the gears at top speed.
Demerit of increasing the number of shifting gears
Higher replacement cost of parts
The current DURA-ACE and ULTEGRA have 12 and 11 speeds, and 105 has 11 speeds, so if you want to upgrade to a rear multi-step component such as 11 speeds, you will need parts for 105 or higher. The cost of parts is higher than lower grades.
For example, if you broke your STI lever in a fall, a new ST-R2000 for an 8-speed CLARIS will cost about $160 for both sides, but a new ST-R7000 for an 11-speed 105 will cost about $220 for both sides, a difference of $60.
Consumables are more expensive to maintain.
The number of shifting gears on road bikes has increased over the years, but the end width (the width between the wheels) of road bikes has remained about the same as in the past. This means that as the number of shifting gears increases, the sprockets and chains are getting thinner.
Thinner sprockets, chains, and other consumable parts mean that their life expectancy is reduced, so they need to be replaced more frequently. Moreover, the higher the number of gear shifts, the higher the grade, so replacement parts are not cheap, so maintenance costs become higher.
If you ride a bicycle because you like it, there is no problem at all, but if you ride it as your everyday footwear, the cost of consumable parts is important, so you need to think about this carefully.