The axle plate is the Rohloff solution to tackle the inherent phenomenon of axle rotation and twisting in all internal gear hubs (IGH).
Historically this rear wheel issue has been easily solved in threaded axle hubs by using non-turn washers at the axle nuts or alternatively installing an ugly long brass arm clamped to the chainstay.
But since in 1998 Rohloff became the first high-end IGH offering a quick release version (and the unique until NuVinci added a QR option last year) a new design needed to be implemented instead of manufacturing a solid thru-axle with two flat sections where secure the tab washers.
The quick release (QR) is one of those features that are a MUST on a bike as it offers ease of wheel disassembly. Aside the low entry specs market, on mountain bikes the percentage is close to 99% except those riding single speed hubs or heavy load duties (tandems and so on).
The Rohloff was intended since the beginning for the top notch MTB/flatbar hybrid ghetto. Heavy duty all terrain bikes to sum up. That’s the reason it only came out and remains with a 135mm axle width and only flatbar shifter installation possible.
The axle plate in the Rohloff speech is the invention that will engage the hub securely preventing the axle from twisting whilst the rider applies force on the pedals, and also turning when shifting providing crispy gears. In physics this force is refered to as torque and must be secured somehow to a stationary point.
The axle plate comes in all RH units, and is part of a modular system that makes any frame with 135mm spacing, and any brake system out there, compatible with its assembly. There are three plates available.
They all have a hollow peg where the skewer passes through (remember this it’s not enough by itself to secure the hub) and an appendix or slot in its outer diameter to seat it properly to the frame. The difference between the three options is the fastening point to the frame.
Most of the times in a certain bike setup more than one solution is elegible. It will depend on the user/framebuilder preferences. As a consequence, there are many combinations possible because the axle plate choice should be pondered over with the core issue of how are we going to remove the chain slack in bespoke configurations growing the alternatives.
Let’s see some in the flesh:
- Bikes with rim brakes installed will have to use the standard axle plate with a long torque arm attached to the chainstays.
If the frame has an unused IS disc brake mount, the long torque arm can be removed and OEM2 mounting is doable by using the lower support hole.
Some users riding touring bikes with no disc brake mount or frames with special needs, managed to remove the long arm screwing torque support bolts on the mudguard/carrier fittings or close locations.
From now on OEM and OEM2 plates will cover the specific issue when installing the bike on a disc setup.
For standard MTB/ATB disc brake frames exists the OEM2 mounting. This is the one to consider when upgrading a bike or for simplicity reasons. I’ve got it in my bike as it came originally with standard vertical dropouts and a conventional drivetrain.
Now it is time to introduce the Speedbone. In the previous picture you can see the plate engages the shiny pin of a bigger arm called Speedbone that goes screwed to the disc brake adaptor from the other side of the frame mount.
The Speedbone has been superseded since the Monkeybone allows to anchor the axle plate directly to the disc brake mount adaptor with no downsides. Very clever!
In any case the Speedbone is still necessary if you’ve got an IS direct mount brake caliper.
The Monkeybone is a witty solution but not suitable for frames ready to go with postmount brake calipers though. Its groundbreaking appearance (sourced by an independient company) forced Rohloff to include it within the official accessories considering its importance. We will see shortly why.
In an attempt to simplify the RH configuration the company specified since the beginning what they call frames with RH ready OEM dropouts. This dropout uses the OEM axle plate and is easy to implement when you create a bike from scratch avoiding the hassle of the Speedbone and also the long arm present on bikes with standard brakes in order to secure the torque. Framebuilders could take advantage of an axle plate that comes this time with a notch resting in the lower position unlike the standard and OEM2 plates.
This axle plate is the favourite choice in custom bike builds where no conversion is needed (with or without removable dropouts). Since you can decide the features of the frame you want to ride and hence the dropout style, you can combine a RH OEM dropout with a sliding system to take up the slack in the chain saving even more weight.
On disc brakes where an IS/PM adaptor is necessary (the most common configuration, 95% of users?) the alternative of the Monkeybone has gained atenttion. With any type of rotor size compatibility in option and considering it integrates the look and functionality of the Rohloff OEM dropout design (even lighter) there is no need for framebuilders and users to stick to a pure RH frame just in case they want to move back to standard transmissions and also reducing frame costs. This is something to bear in mind as I said before with the method desired to provide chain tension.
All in all, 90% of bikes over 1000$-€-£ and suitable for a Rohloff have disc brakes. That’s the importance of the Monkeybone. Nearly every single mountain/hybrid bike frame will be likely and preferable to be used with the OEM2 axle plate relegating the OEM axle plate, and thus the specific design dropout, to a 10%-15% of community wishing custom builds with rim brakes and/or sliding dropouts combinations.
Finally, I’d like to point out that all the axle plates come with 12 holes drilled equally around the circumference. This hole pattern allow adjustment of the external gear mechanism in steps of 30º so that all type of frames can receive an optimum cable routing from the rear wheel.