| Model Number | WH-6600-G | |
| Series | ULTEGRA SL | |
| Wheel | front | rear |
| Brake Type | rim brake | rim brake |
| Freehub Body Material | - | aluminum |
| Cassette Compatibility | - | 10-speed |
| Over Locknut | 100mm | 130mm |
| Axle Type | Quick Release | Quick Release |
| QR Skewer Length | 133mm | 163mm |
| Axle Length | 108mm | 141mm |
| Axle Material | steel | aluminum |
| Contact Seal | yes | yes |
| Hub Shell Material | aluminum | aluminum |
| Hub Shell Finish | anodized | anodized |
| QR Lever Material | aluminum | aluminum |
| QR Lever Finish | anodized | anodized |
| Rim Type | Clincher | Clincher |
| Rim Size | 622x15C (700C) | 622x15C (700C) offest |
| Rim Material | aluminum | aluminum |
| Rim Finish | anodized | anodized |
| Rim Height | 24mm | 24mm |
| Rim Tape Recommended | ||
| Rim Width | 20.8mm | 20.8mm |
| Spokes | 16 | 20 |
| Spoke Gauge/Shape | butted (2.0/1.8/2.0) / bladed | butted (2.0/1.8/2.0) / bladed |
| Spoke Material | stainless steel | stainless steel |
| Spoke Color | Black | Black |
| Nipple Material | aluminum | aluminum |
| Nipple Color | Black | Black |
| Spoke Protector (Option) | - | CP-WH20-A |
| Spoke Configuration | ||
| Reflector (Option) | CAT EYE: RR-550-WUW SW W/O BRACKET (JIP/CPSC), RR-550-WUA SW W/O BRACKET (AS), RR-317-WUA SW W/O BRACKET (DIN) | |
| Average Weight | 753g | 943g |
| Note | Weight does not include quick release |