- OSPW - Over-Sized Pulley Wheel
- Half Tooth pulley wheels to reduce friction contact with the chain
- Delivers the reduced articulation benefits of oversized pulleys
- Lightweight from 49g due to carbon fibre and aluminium construction
- Available for Shimano and SRAM rear derailleurs
- Full Ceramic bearings for smoother and long-lasting operation
Half Tooth jockey wheels
Choosing an oversized pulley wheel to gain the benefits of reduced chain articulation will naturally add weight and potentially lose stiffness and, therefore, shift precision. Several techniques have been tried to minimise the contact points between the chain and the pulley wheels.
Furay introduces the HT (Half Tooth) concept, which aims to overcome the additional contact by removing half of the teeth. The HT concept allows the weight to be kept to a minimum despite the pulley wheels being larger. With lower teeth count, a side benefit has been a reduction in mechanical noise from the chain.
The upper pulley is the main guide and is responsible for shifting, so stiffness and precision are essential here. The pulley is kept close to the original 11T version size, but with only 6T, so it gains the friction benefit. The bearing is also large to ensure the pulley is stiff to provide precise shifts, and because of the strength, it can use a single-sided carbon fibre arm for the lower pulley.
The lower pulley is oversized to reduce articulation and also maintains the tension in the chain. The 18T equivalent pulley wheel in size but has only 9T; it is designed as 3 spoke wheel for aerodynamics and uses a small bearing mounted to the single carbon fibre arm . The carbon fibre arm has been optimised for aerodynamics-ultra marginal gains, but why not.
This is very similar to the R8000/R9100 version, except the upper wheel is 16T equivalent (actual 8T) and has two carbon fibre arms to connect to the lower pulley.
Ultimately both versions are pushing for those marginal gains with savings of 3.5-5watts (depending on gear/chain angle). They are also significantly lighter than competitor versions.
Shimano R90XX/R68XX Series compatible - Upper 16T Lower 18T equivalent pulley size (actual 8/9T) Weight: 49g
Shimano R91XX/R90XX/R80XX/R68XX Series - Upper 12T Lower 18T equivalent pulley size (actual 6/9T) Weight: 49g
SRAM RED11S/11S ETAP/FORCE 2*11S/RED AXS/FORCE AXS - Upper 12T Lower 18T equivalent pulley size (actual 6/9T) Weight: 51-53g
Carbon fibre arm and AL7075 aluminium ceramic-crystal anodised jockey wheels
Bearings: Full ceramic