Rim Brake Location for 700x30, and calipers that clear 30mm

I just posted this as a new topic, but thought I would add here to catch all potential interest!

Hello builders,

As some of you will know, a while back I worked with Craig Edwards on prototyping a version of the EE brake to clear large volume tires. This is a direct mount brake, with the bosses at 58mm width.

You can see a set of the prototype brakes on this build:

Performance is the same as the regular brake, but with clearance for up to 45mm tire width (or maybe a bit bigger depending on tire/rim). Or 40mm tires and fenders fit very comfortably.

Cane Creek are willing to do a very limited production run of these brakes, but all will need to be pre-sold. They are saying: “We are far away from our vendor MOQs, so we’ll have to pay prototype-level prices for the gravel specific parts. So the gravel eeBrakes will be $300 each/$600 per bike.”

If you are interested in any quantity of these brakes, please send me a message saying how many you would like. If there is enough interest then I can organise the group purchase and delivery would likely be in March.

thanks, Rob.

2 Likes

Bringing the thread back from the dead. After riding my new rim brake road bike (with 700x32 tires), I am convinced rim brakes still have a place in modern bike design. The hood size feels so pleasant in my hands. Braking is not an issue even at 200lb and SF’s steep hills. What was shocking was how comfortable the bike feels compared to my titanium disc brake bike w/ ENVE allroad fork and deep carbon wheels.

The caliper clearance on the fork was close! The limiting factor is the height of the tire:

I tried to land the rear brake at 358mm from the axle. It ended up .5 mm too high. Either it shifted higher during manufacture, or the SRAM RED calipers don’t have as much pad reach as claimed. If I were to do it again, I would aim for 356mm, especially since the fork was the limiting factor.

Direct Mount (Again)

Rim brakes can get a serious update with wider tires, rims, and brakes. I know people will suggest long-reach calipers, but raising the caliper (and having longer arms) reduces the mechanical advantage of the brake. I don’t like designs that are 1 step forward and .5 steps back because I know we can make 3 steps forward.

The mechanical advantage of direct-mount brakes does not change given tire clearance. After spending a weekend researching bike and brake designs I came across this brake: the Tektro T750R

image

This brake could allow for whatever spacing of the posts (within reason) without affecting the mechanical advantage. Allowing us to prototype and experiment with different brake post widths.

Unfortunately, the trail runs cold - I can’t seem to find this brake anywhere.

3 Likes

Before you rule out mid-reach calipers, you should give them a try first. Maybe you already have and haven’t mentioned it yet. But I think their performance is indistinguishable from short-reach calipers.

I think I offered this before, but I have a Whisky fork and some TRP calipers you can borrow for testing.

I’d love to see your project take off. Bringing back a practical road bike would be a big win.

3 Likes

A while back, I owned a Synapse with long-reach brakes; they were spongy. It could have been the Tektro calipers or the weird rear cable routing. I am sure the high-end TRP and Velo orange calipers are stiffer.

Even the latest generation Shimano “dual pivot” style brakes of the R8000 and R7000 are a huge step up from all the TRP and SRAM brake calipers. The Shimano style is based on a direct mount design, with independently pivoting arms and a stiff brace to connect them:

I am actually working on a XXS 650x38 bike design with long-reach calipers right now, but that is what lead me down the rabbit hole of direct mount again. The direct mounts have the potential to create better brakes and open up the design space for new designs. For example this linkage style Bontrager brake:

By swapping the main bulkhead and the pull link, one brake product could accommodate multiple direct mount post width standards: road, allroad, gravel. All without compromising the stiffness or mechanical advantage.

@Daniel_Y, I would love to see you work with Rolf/Astral to test current brakes (direct and standard mount long and short reach) before designing a new brake and standard.

It looks like their test rig could be a great starting point to test the effectiveness of a broad range of brakes. With their commitment to rim brake wheels I think it would be a great collaboration and marketing story to work with you through this process of finding/making the best rim brakes available.

You may find that one of the standard mount long reach calipers with the pads high on the adjustment range provides exceptional braking so you don’t need develop a new brake. Or you’ll come away with a metric to beat with your own design.

If you do end up making a new brake, I really hope you design it for both direct and standard mount similar to the EE brakes that share 90% of parts between both mounting styles. To be honest, I don’t like the aesthetics of direct mount and would rather have the ~8% worse braking.

3 Likes

YouTube told me about these brakes. Never heard of them before since I don’t do triathalons. But it appears they can clear a 34mm tire and can be used for direct or standard mounting.

3 Likes

I recently discovered these too! Interestingly enough, they don’t actually mount directly to direct mount frames. They use an adapter plate to go from a direct mount frame to the standard mount caliper. Presumably because they widened and lowered the pivots (just as Daniel is looking to do).
Screen Shot 2024-04-12 at 12.21.09 PMScreen Shot 2024-04-12 at 12.21.31 PM

It looks like they recently updated this Aero Brake but have yet to update their SL Brake. It would be rad to see them update their SL Brake with the same clearances.

2 Likes

These are neat, who knew roller-cams would make a come-back as road brakes? :rofl:

2 Likes

Found this today as I was looking for info on Velo Orange Grand Cru Brakes

Clearance Pt. II - Road Frames - Black Mountain Cycles (blackmtncycles.com)

And, FWIW, V.O. confirmed that their brakes can handle rim width up to 30mm.

2 Likes

Not completely relevant to this thread but the VO’s can clear 38s if the frame and fork are built to use every last mm of pad adjustment. David Kirk builds quite a few of his “MRB’s (Montana Road Bike)” doing exactly that.

Screen Shot 2024-04-12 at 3.36.47 PM

3 Likes

Very cool. I was wondering about that. Looks like a fun bike.