Description
The Altus RD-M310 is a light action MTB rear derailleur for 7/8-speed shifting systems. It features a low profile concept with double servo-pantograph technology that improves adjustability and resists weather and contamination. The rear derailleur always keeps close to the cassette sprockets, allowing smooth and effortless gear changing. Wide link for durability and precise shifting.
Product Features
- Compatible with 7 and 8-Speed shifters
- 13T upper pulley and 15T lower pulley
- Wide link design for more rigidity and precise shifting
- Advanced light action
- Smartcage pulley plate
Specifications:
Speed: 7 Speed, 8 Speed
Shifter Compatibility: Shimano Road & Mountain
Shift Mechanism: Cable Actuated
Max. Tooth: 34T
Min. Tooth: 11T
Chain Wrap Capacity: 43T
Cage Material: Steel
Chain Retention: –
Color: Black
Weight: 326g
FITTING AND ADJUSTING TIPS
SIZING
How to measure your foot length
- Stand with the heel to a wall and put a measuring tape under your feet
- Read off the measured foot length in millimeters before your longest toe
- If you are between two sizes, choose the next higher, because feet are minimally greater under load
You can also use our template:
Download the foot measurement template
Birkenstock products are offered in European sizes. Please reference our Size and Width conversion charts below to determine your SA/UK size.
Your feet should be able to move freely without your toes hitting the edge of the footbed.

Before trying them on, put one hand under the toe and one under the heel, then flex the footbed a few times. This will initiate the break in period and will your help your new sandals feel comfy sooner.
Open all straps and step into the footbed. Close the straps comfortably, leaving enough space to allow your feet the freedom of movement. Exhale and enjoy.
For the first five or six times you wear your new footwear, limit the time to just a few hours. This allows your feet and body to gradually get used to the contoured arch support as well as the straps and buckles.