Condensed Answer: A 10-speed front derailleur can be combined with an 11-speed drivetrain, but the setup is not ideal because the derailleur’s cage is slightly wider and can create shifting issues.
For best performance, it’s better to use a front derailleur designed for 11-speeds.
How Do Front Derailleurs Change With Gear Each Gear Increase/Decrease
Front derailleurs are not as pretentious as rear derailleurs. Nonetheless, they also have to adapt to some drivetrain changes that happen with each gear increase or decrease.
Below is a list of those adaptations.
- Derailleur Cage Width
The width of front derailleurs’ cage depends on the chain’s width.
The wider the chain is, the wider the cage has to be.
Chains have two widths – inner and outer. The outer width is the distance between the external plates whereas the inner width is the distance between the internal plates.
The internal width of a chain doesn’t change or does so slightly with each gear increase and decrease because the overall thickness of cassette cogs remains the same.
The inner width of 10 and 11-speed chains is identical at 2.18mm.
The table below contains the inner and outer widths of 7-12 speed chains:
|Number of Speeds
|7.3mm (Shimano), 7.1mm (SRAM)
|7.3mm (Shimano), 7.1mm (SRAM)
As shown in the table, the outer chain width decreases with each gear increase.
Why? Manufacturers try to keep the overall width of cassettes the same so that one rear hub can accept cassettes of different speeds. To keep the width of cassettes within tight margins, the spacing between the cogs gets smaller.
As a result, the chain has to get thinner or it will rub against the cogs surrounding it.
Since the inner width cannot be decreased, the only option is to decrease the outer width by thinning out the outer plates.
For that reason, when all parameters are equal, chains designed for fewer speeds are stronger thanks to their additional thickness.
In the case of the discussed topic, we have a 10-speed derailleur designed for a 10-speed chain. 10-speed chains are approximately 5.9mm wide whereas 11-speed chains are about 5.4mm.
Consequently, the cages of 10-speed front derailleurs are expected to be 0.6mm wider than those of 11-speed models.
The Problems That a Wider Derailleur Cage Creates
The wider cage creates the following issues when using a narrower chain than originally intended:
- Shifting Latency
Shifting latency occurs because the front derailleur has to travel slightly more to reach the narrower 11-speed chain to move it.
- Potential Overshifting
To reduce the latency, some users might tweak the limit screws on the derailleur to push the inner side of the cage closer to the chain.
This adjustment will eliminate the latency problem but will push the outer cage too far out.
When the FD’s cage is over the large chainring, it won’t be balanced evenly against the outer sides of the chainring. In extreme cases, this may cause overshifting and a dropped chain.
- Poor Clearance Against The Cranks
Another issue that the outboard position of the front derailleur can cause is contact between the drive-side crank arm and the derailleur’s cage. This applies only to road bikes as they have straight cranks whereas MTB cranks have a slight curve to clear out the wider chaintays.
Below is a list of questions that people interested in the main topic might find helpful.
Are 10 and 11-speed chainrings the same?
The thickness of 10 and 11-speed chainrings is approximately the same, but they’re spaced differently.
The distance between 10-speed chainrings is slightly wider to make space for the wider 10-speed chain.
Meanwhile, 11-speed chainrings are closer together because the chains designed for them have a narrower outer width.
The smaller spacing results in smoother and faster shifting. (It simply takes less effort for the front derailleur to move the chain.)
Can I use an 11-speed front derailleur in a 10-speed drivetrain?
Technically, yes. But 11-speed front derailleurs have narrower cages because they’re made for 11-speed chains.
When coupled with a 10-speed chain, the derailleur’s cage may rub against the outer plates of the chain due to the insufficient width. In such situations, trimming of the front derailleur could help.
Nonetheless, it’s still recommended to get a 10-speed front derailleur.
Will a 10-speed rear derailleur work with an 11-speed cassette?
10-speed rear derailleurs do not work accurately with 11-speed cassettes when coupled with index shifters.
The only exceptions are SRAM’s 10-speed exact actuation road derailleurs which have the same rear shift ratio as SRAM’s 11-speed road (exact actuation) and 10-speed MTB (exact actuation) derailleurs. (read more).
Can I use a 10-speed front derailleur with a 9-speed chain?
A 10-speed front derailleur can operate sufficiently well with a 9-speed chain. The main issue to look for is the rubbing of the chain against the derailleur’s cage (read more).