The Greeks, oops, I mean geeks*, at SRAM are at it again, but what exactly is the end game of their latest Trojan Horse, a UDH-like push to standardize brake mounting on frames (and forks?).
*{Meant with affection}
Mountain bicycles were perfected years ago, and in the time since then no minor elongation of maximum dropper post travel, electrified tubeless valve stem, or fancy carbon rim shape has managed to generate a pressing need for folks to replace their current rig. Even going all-in on eebs apparently can’t save iconic brands from becoming the next Diamondback.
But never fear gentle marketing team members. Yes, the only immediately obvious advantage of the semi-axle-mounted design is that the threaded component that our brakes mount to is easily replaceable should said threads be damaged*. But it clearly has to be something more?! Something experience changing!? What Odysseusness are they up to this time?!
*{Like any IS brake adapter going back a quarter century.}
No, I can’t answer the one UBM (Universal Brake Mount) question that everyone is burning to know – Can you now also put your bike on the ground derailleur side down and stand on it? – but I do have some theories on what they might be getting up to.
I’ll note here that I have no inside information, so if there’s any truth to what I’m writing it has nothing to do with the fact that I occasionally bump into Stephen Matthews at the S’wich Cafe – Sandwich Shop*. (Don’t worry Stephen, they’ll never suspect us of colluding now).
*{Drewitors note: A name drop and a plug in the same sentence!}
I’ve put a bit of skin into the game by placing these into my order of suspected likeliness, but I’ll also contend that the UBM may allow for multiple exciting fresh, and refreshed, features either rolled out all at once or over time.
1) Powertrain & Flight Attendant AXS Sensor Module
I keep wondering when we’ll see 30% smaller AXS-2/eTAP-2 battery packaging. It will inevitably allow for a slimming of the current form factor of derailleurs, suspension, and dropper posts. It will hopefully also be backward compatible with the current generation using the same footprint or an adapter.
Until that time comes we have to assume that anything using AXS batteries requires a minimum amount of real estate, and the UBM certainly has enough space to quietly (visually) contain such an animal. Is it just a way for SRAM to cleanly package, and quality control, swingarm battery mounting?
Why such a big battery on the brake mount? Imagine you were trying to wirelessly juice wheel sensors for an eeb motor (Powertrain), automatic shifting (Transmission), anti-lock braking (SkidWiz?), and automatic suspension adjustment (Flight Attendant). That sounds like thirsty work to me!
{Above photo: Danny Milner / MBR}
2) Full Mount Braking
One of the key design and selling features of T-Type AXS wireless, and presumably T-Type cable, drivetrains is a precision alignment of the hub and derailleur that allows SRAM to do away with the weird wizardry of adjusting high and low limit screws*. Imagine a future Full Mount brake caliper that is just bolted straight to the axle and frame and requires zero additional adjustment to put the brake rotor in the center of the pads.
*{A) Transmission/T-Type still has B-Tension adjustment it’s just friction based instead of being held in place by a screw. B) I still prefer limit screws.}
Now old folks might be giving me prune-face right now as they remember shimming IS-to-IS brake calipers, adapters, or rotors. And someone wants to point out that Center Lock (CL) rotors don’t allow for any inboard-outboard adjustment but, to steal from Abbey Tools, precision wasn’t religion back then despite the best intentions of international standards for IS mount placement and disc hub dimensions.
I find it easy to imagine myself manically massaging the pistons on – front & rear – axle-mounted, fixed-position, Maven calipers to get the pads sitting perfectly next to a rotor and then the ensuing spiel about how I’m just a grumpy elitist gatekeeper because I want people to value my mystic knowledge of the old ways of brake/derailleur adjustment.
3) Suspended/Floating Brake Mounts
Many past examples of coaxial brake mounts are integrated with floating brake arms designed to isolate suspension performance with braking. This is a concept that has gone in and out of the light every three to five years for almost as long as sag wagons have been around. I’d guess this largely comes down to appearance (ugly) and maintenance (floating brake arm rattle is the worst).
But I can imagine the smart folks at SRAM coming up with a much sleeker way to integrate the floating brake arm, which attaches to the front triangle. I also wonder about semi-isolating braking forces via an axle-mounted brake caliper and ButterCups-esque suspension module built into the UBM.
Either way, why couldn’t this integrated isolation of suspension and braking forces be brought up front to the fork as well?
{Above photo: BikeRumor / Boris Beyer}
Add-Ons?
I have a few other more fanciful ideas but tried to keep this in the realm of reason. If you have a solid theory and you’d like to add it to the list fire me a paragraph and I’ll post it here so we can look back and laugh – or in wonder – when SRAM unlocks the gates one night while everyone is sleeping.
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