85 road hubs from Boyd Cycling. Simple, smooth, quick, effective.
Flange Sizing and Spacing
The spacing and sizing of the flanges is one of the most important things to ensure a stiff wheelset. I like to think of a wheel more as a triangle versus a circle, where the hub is the base of the triangle and the rim is the top point of the triangle. When designing a triangle, to make it more structurally sound, you want to increase the base as wide as possible. This helps to increase the bracing angle, the angle at which the spokes enter the rim.
With the front 85 hub we could push the flanges out almost to the edge of the hub. This helps to ensure a very stiff and well responding front hub.
Front hub measurements:
Center of hub to center of flanges – 39.0mm
Flange spoke hole diameter – 36.5mm
With the rear hub, it’s not as simple as just pushing out the flanges as far as possible. On the drive side, the position of the cassette prevents the flange from being placed at the edge of the hub. We wanted to move the right flange out as far as possible to help with the bracing angle. Because the drive side flange cannot be moved very far from the center of the hub, every tenth of a millimeter is important. . . much more so than flange height! As you move flanges further out, the height of the flange affects the bracing angle of the spoke quite a bit. However, the more directly under center the flange is, the less height affects the bracing angle. For example, if you changed the height of the drive side flange from 50mm to 100mm (double the flange height), that is the same change in bracing angle as moving the flange outward by 0.3mm.
On the non-drive side, there is much more room to push the flanges outward as there is no cassette in the way. However, as you push that flange outward the tension of the non-drive side spokes will drop to keep the rim in dish. Finding that good balance between tension ratio and flange width was a priority. We designed the OLD measurement of the hub to be 131mm instead of 130mm in order to help with moving the flanges wider and keeping good tension ratio.
With the rear 85 hub the measurements are as follows
Drive side spoke hole diameter – 55.5mm
Center of hub to center of drive side flange – 17.3mm
Non-drive side spoke hole diameter – 44.5mm
Center of hub to center of non-drive side flange – 37.7mm
This gives a drive side to non-drive side tension ratio of approximately 49%. Meaning if you build the drive side to 125KgF the non-drive side tension will be just over 61Kgf, more than enough to keep the spokes in tension and prevent going slack. The massive 55mm of spacing between flanges will ensure a very stiff wheel build!
Bearing sizes are often overlooked when looking at the performance of the hubs. Smaller bearings will save weight, but can come at the expense of a lower static load and decreased durability. We studied the loads of different sized bearings and in the end the increase of 5 grams per bearing was more than worth it for years of durability and increased stiffness of the wheels.
Bearing sizes are as follows
Front hub – 2X 6901
Rear hub – 2X 6902 in the hub shell; 2X MR15267 in the freehub body
Freehub body engagement
Engagement speed is mostly talked about in the mountain bike world, where a fast-engaging hub can be the different between making it over that rock garden or having to dismount. On the road scene, quick engagement is more of an afterthought and usually deemed not necessary.
However, we work with a lot of teams who race criteriums and the feedback is the quick engagement of the 85 hubs is very critical when jumping out of a corner multiple times per lap. There is a confidence inspiring feeling to stomp on the pedals and immediately have the bike respond, even when riding on the road.
The 85 hubs share the same freehub body and engagement as our Quest disc brake hubs. The 36 teeth and 6 pawls engage in a 3 by 3 manner which works out to a very quick 5 degree engagement.
Press fit axle and end cap design
To keep everything as simple as possible, we have moved to a press-fit end cap system. Everything is designed to be within tolerance so when you press the end caps on the system is smooth rolling with no play at all. Clamping the hub in the frame with a skewer or end cap keeps the hub tightened together.
This system means there is never any adjustments needed. You never have to worry about if your end cap is tight or loose or if your hub needs work. Just put the wheel in your frame and ride!
This keeps the hub extremely easy to service with no tools required. If you need to access the freehub body and pawls, you simply pull the end cap and freehub body off.
Future proofed thru axle compatibility
Thru-axles for rim brake bicycles are coming! Yes, you read that correctly. While disc brake bicycles are obviously going to become more and more popular, rim brake bicycles will always be around and popular. One of the reasons why people enjoy riding a disc brake bicycle is the increased stiffness and security that comes with a thru axle frame and fork. It’s only logical that at some point, rim brake bicycles are going to follow suit and start coming equipped with thru axles. We have designed the 85 hubs to be future proofed for when this happens. So, buy with confidence! In three years if you buy a new bicycle that is rim brake and thru axle, you simply only need to swap end caps and you can use the 85 hubs on the new bike!
Bearing are the most important part of the bike. Without them your wheel would not spin. Having good bearings in the hub helps them to spin well, and can provide years of trouble free riding. The hubs come stock with a high quality Revo cream precision bearing. Revo Cream premium bearings are made from high-carbon chromium steel and packed with a special blend of corrosion resistant Mobil grease. Each Revo bearing is designed for a specific cycling application and features a high-impact, high-sideload design for durability and long life.
Everybody likes a lightweight wheelset, but we have always had the premise that products can be designed reasonably lightweight and still have great durability. Rather than try and shave 10 grams from the weight of the hubs at the expense of stiffness and durability, we wanted to have a hub that would give you years’ worth of hassle free riding.
Weights for the hub are as follows
Front – 100 grams
Rear – 254 grams