Shimano Deore is an MTB group set from Shimano. Consequently, one cannot simply install Deore parts on a road bike and expect them to work as intended right out of the box.
That said, there are a few pathways that can be followed for using some Deore components on a road machine.
Rear Derailleurs and Shifters
Modern shifters are indexed. In simple words, this means that the movement of the shifter is segregated into clicks. Each click results in a shift. The cable movement that the shifter generates is known as cable pull and is pre-determined and non-changeable.
The benefit of index shifters is that they make the shifting experience fast and efficient. A shift requires just a click.
The pre-determined cable pull is not enough to ensure predictable movement of the rear derailleur. Hence why derailleurs have strict rear shift ratios.
The rear shift ratio of a derailleur indicates how much the derailleur moves per 1mm pulled or released by the shifter. For example, if the rear shift ratio is 1.7, then the derailleur would move 1.7mm for every millimeter of cable movement.
The cable pull and the rear shift ratio vary according to the number of speeds that a bike has and its type (road or MTB).
Hence why it’s not always possible to mix MTB and road parts.
The table below shows the rear shift ratio of Shimano’s derailleurs. Deore parts come in 8/9/10/11/12-speed format.
| Brand | Number of Speeds | Rear Shift Ratio (MTB) | Rear Shift Ratio (Road) |
| Shimano | 8 | 1.7 | 1.7 |
| Shimano | 9 | 1.7 | 1.7 |
| Shimano | 10 | 1.2 | 1.7 |
| Shimano | 11 | 1.2 | 1.4 |
| Shimano | 12 | 1.2 | 1.4 |
Shimano’s 8/9-speed MTB and Shimano’s 8/9/10-speed Road derailleurs have the same rear shift ratios, namely 1.7.
This means that an 8 or 9-speed Shimano Deore derailleur can technically be integrated into an 8/9/10-speed Shimano road drivetrain.
Derailleurs are not “smart”. They are controlled by the shifter and have no idea how many speeds a bike has. As long as the derailleur has the correct rear shift ratio and the capacity to cover a cassette, it will work. And since MTB derailleurs have equal or greater capacity than road derailleurs, the capacity is not an issue when using a road cassette.
Note: It’s possible to integrate 10 and 11-speed Deore derailleurs into a road drivetrain by relying on Wolf Tooth’s Tanpan adapter which is installed before the rear derailleur to adjust the cable pull of the shifters. (read more).
Cassettes
A Deore cassette can also be installed on a road bike when the following conditions are met:
- The hub is designed for 8/9/11 or 12-speeds and uses the HyperGlide architecture (not Microspline).
Shimano’s 10-speed road cassettes are narrower than 8, 9, 11, and 12-speed models. Consequently, the matching hubs are narrower too. Hence why it’s not possible to combine a dedicated 10-speed road hub with anything other than a 10-speed road cassette.
Note: Some 10-speed road bikes use an 11-speed hub with a spacer to make up for the non-used space. If you remove the spacer, you will be able to fit an MTB cassette on that hub.
- The derailleur needs to have enough capacity to move up the entire cassette.
Most road bikes use high gearing and have derailleurs that cannot be combined with cassettes that have a large cog with more than 34 teeth. In that case, it will be necessary to replace the derailleur or use a derailleur hanger extender.
Shifters
Deore shifters are designed for MTBs and thus can only be mounted on flat and urban handlebars. Technically, you can put such shifters on the flat part of a road bike’s drop handlebars, but then you will lose the ability to shift while riding in the hoods or the drops.
Thus, using Deore shifters makes sense only if you have a flat bar road bike.
If you plan on using Deore shifters, you may have to use an MTB derailleur in some cases due to the dissimilar rear shift ratios and cable pulls of road and MTB bikes.
The table below contains the cable pull of Shimano MTB and road shifters.
| Brand | Speeds | Cable Pull (road) | Cable Pull (MTB) |
| Shimano | 8 | 2.8 | 2.8 |
| Shimano | 9 | 2.5 | 2.5 |
| Shimano | 10 | 2.3 | 3.4 |
| Shimano | 11 | 2.7 | 3.6 |
| Shimano | 12 | unknown* | unknown* |
*There isn’t accessible data that can reveal the cable pull of 12-speed Shimano MTB and road shifters. It’s known, however, that the numbers are different from those of 11-speeds parts.
When you take into account the rear shift ratios posted above and the cable pulls, we get the following viable combinations:
- 8/9/10/11/12 Deore shifter + 8/9/10/11/12 MTB Derailleur
- 8/9 Deore Shifter + 8/9/10 Road Derailleur
Front Derailleur
Installing a front MTB derailleur on a road bike can cause issues because road and MTB bikes have different seat post angles. Moreover, road chainrings are larger and road derailleurs have longer cages to ensure smooth shifting. For that reason, it’s not recommended to install an MTB front derailleur on a road bike.
Cranks
Technically, it will be possible to install Deore cranks on a road bike as long as the bottom bracket is the correct type. However, it’s recommended to stay away from this practice because MTB and road cranks are different.
Road cranks are closer to the frame whereas MTB cranks are further away. Thus, if MTB cranks are installed on a road bike, the chain line will be off. The result is subpar shifting and loss of efficiency.
