That’s pretty much what I guessed at - now just trying to find somewhere to buy some half decent (DT or Sapim) 14g black spokes not in boxes of 72 or 100 
These also look like a low profile caliper, but looks can be deceiving, so I sent Clarks an email asking about dimensions.
On my Oregon, running a D Brake adaptor and a 160mm rotor, 150 Venture II’s, with a 4mm bearing spacer, there is a maximum of 35mm of caliper clearance. The Quads would NOT fit.
The Quads might fit with Moments due to their higher Q, also a bigger disc would increase clearance with a high Q crank.
Keep in in mind that clearance will also vary depending on how far a crank goes onto the spindle, so if you don’t have much clearance and later you need to reduce the bearing spacer for crank creep, you may hit the caliper.
For comparison, a BB7 is 42 mm from disc center to outside, an Avid Juicy 7 is 30mm from disc center to outside. Add 5mm for a safe zone.
Glad I didn’t go for the BB7s then!
I suppose it doesn’t matter how thick they are on a bike as they’re just extending into air rather than towards a crank.
Hey Mowcius, I went down this road once before, when I first got my Oregon and wanted a different brake than the white Bengal, so I played around with the BB5/7, but they’re just too wide.
I have taken measurements from other brake clipers including the Hope mechanical and the Tektro mechanical, both were too wide.
Because there is no incentive to make a low profile (compact) mechanical caliper being as they are less popular and lower quality than hydraulics, they tend to run wide.
Roger, do you remember the name of the mechanical brake you tried that had sufficient clearance?
From Chain Reaction Cycles in the UK in response to my question about mechanical disc brake caliper width:
Maybe the Tektra Lyra would work with Moments?
Apparently the Tektro Lyra is a cyclocross brake, weighing in complete at 148gm! Reviews are few, but here’s a discussion piece from a cyclocross forum:
Maybe, but its standard rotor is only 140mm. Can you get it with a larger rotor?
I’m thinking the Quad QMD6 with a 180mm rotor and Moments is looking like a pretty good bet. Also with the Moments, at least for the type of XC riding I do, I’d be comfortable shaving a couple mm off the crank if necessary.
The Lyra comes with a 140mm or a 160mm.
I ride a 160mm on the Oregon and it is plenty powerful, anything bigger is just extra weight.
I will probably order a pair and see what they do.
One more thing, many disc brakes come without a rotor, so the caliper will be designated for a certain rotor size based on the adaptor sold with the caliper.
But any increase in rotor size can be accomodated by changing to a larger adaptor, so the Lyra could be used with a 203mm rotor if you bought the appropriately sized adaptor.
Well, that’s great news, looks like we have two contenders for mechanical disk brakes with the new hub!
I really like the look of the disk for the Lyra.
Now to try to find reviews of these brakes. . . .
Lyra reviews
I found two reviews of the Lyra, one negative, one positive, here:
http://www.bikeforums.net/archive/index.php/t-496235.html
Text inserted below for preservation.
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Anyone using/used Tektro Lyra disc brakes?
twoflats12-21-08, 08:41 PM
I can’t find any reviews or much any other information online about how these brakes perform, so I’m hoping that someone on here might be able to give a reasonable, brief review on these brakes. How do they compare to BB7s?
Thanks!
M_S12-22-08, 01:21 AM
If their like the mountain versions of the mechanical tektros, they are sucky compared to avids.
twoflats12-23-08, 07:13 PM
Well, I guess I’ll be the first person on the freaking (internet) planet to try these brakes out. I just ordered some and will post a review after I ride them for a bit.
twoflats01-10-09, 07:15 PM
First review of Tektro Lyra brakes!
Weights (per wheel):
Caliper: 148g
Rotor: 103g
Mounting bits (adapter + 4 bolts): 35g
The good:
Weight - nearly 100g lighter than the Avid BB7 Road per wheel.
Looks - they are damned pretty.
Brake action/modulation feels smooth, if a little stiff.
Cable tension barrel adjuster on caliper - you don’t need an inline barrel adjuster.
The bad:
Nearly impossible to setup. The mounting bolts don’t have any concentric adjusting washers (like the BB7), so if your caliper mount point isn’t exactly aligned/square, you’re SOL. I ended up borrowing the concentric adjusting washers from a set of BB7s just so I could get these set up.
Rotors were warped out of the box and they’re so flimsy that truing them was nearly impossible. I spent an hour getting them fairly straight, but there was one spot I couldn’t get quite right.
Outer pad isn’t adjustable, so you have to adjust the outer pad by partially closing the brake with the cable arm then tightening the cable. Any further adjustments must be made using the barrel adjuster on the caliper.
Requires too much cable pull. Even after jumping through the hoops to get the brakes reasonably set up, I was unable to get much braking power before bottoming out my SRAM Rival brake levers. The cable supplied with the brake kit is useless. A compressionless brake cable would help here, I suspect, because the crappy cable that came with this brake kit is not even close to a compressionless cable.
Brake pulses under hard braking. This is due to the design of the rotor and where the brake pads contact the rotor–the brake pad extends partially down the arms that attach the outer part of the rotor to the inner, and when that part of the rotor passes through the caliper, it grabs more and results in a strong pulsing under hard braking that made my fork (Nashbar carbon CX) shudder violently.
I ordered a set of BB7 Road at the same time I ordered these so I could compare them side-by-side. In short, there’s no comparison to even make, because the Lyra aren’t useful as they stand. The BB7s are smooth, setup was much simpler, more substantial rotor is easier to true (yes, one of them was a bit warped out of the box, too).
I’d really hoped the Lyra would work for me, because it’s very appealing to save 200g over the BB7; in fact, the Lyra would actually have saved a few grams on the rear of my bike compared to the cantis I had because I can remove the canti mounts from my frame.
Tektro, if you’re listening, you can fix the Lyra by making a few simple changes.
Spend $1 extra and include the concentric adjusting washers on the caliper mount bolts!!!
Make the outer portion of the rotor wider so that the pad overhang doesn’t cause pulsing when it contacts the arms. This is the real show-stopper. These brakes are borderline dangerous due to the shuddering caused by the brake pulsing. Maybe use a square-ish pad instead of a round one, too.
Reduce required cable pull just a bit.
Consider a lighter spring so the brake action isn’t quite so stiff.
Include a compressionless cable or don’t include a cable at all.
acorn_user01-11-09, 01:36 PM
You need some Magura HS77 levers and hydraulic brakes 
Have you tried the Shimano road discs yet? Thanks for the review!
scthomson01-24-09, 01:15 AM
I have been looking at these as well, and had some similar questions.
I had planned to use a different rotor and better housing anyway, but the cable pull issue is problematic. Do you feel it was because of the break-in period typically required? Has the braking force gotten any better since your review?
It seems they would have made the cable pull standard for road levers like the BB7s so I’m curious why there’s a noticeable difference.
Thanks for the help!
stefank02-28-10, 10:53 PM
I built a new winter-commute bike and used it now one season.
For the front I used a Mavic Speed City with Tektro Lyra disk brake;
here is the report.
I used this brake with Shimano Ultegra levers and ordered it with an
in-line Travel Agent. When it all arrived and I began fiddling with it,
measuring the throws and experimenting, I decided I didn’t want the
Travel Agent. I read the docs that came with the thing a second time
and experimented a little more and went ahead and built it without it.
I had no trouble mounting the brake. I just experimented with the mounting
hardware trying to get the center of the pads aligned over the quite narrow
disk surface. The Lyra does not have much width to the disk, I think getting the
center of the pads a little too far inboard would cause unacceptable pulsation.
The disk itself was perfectly true as far as I could measure with a straightedge.
I had no trouble getting the mounting to line up. Lever release definitely caused
daylight between the disk and pads, no problem there.
So how was it for the first winter? The braking power of this thing is adequate but
not impressive. I would say it is a little less powerful than a caliper, that is, with my
setup, I have to squeeze maybe 1/4 harder than I would on my summer bike with
the same levers and a caliper. There is no pulsation. One thing is, for some reason,
after say half an hour of riding in the winter saltbrine the next stop I get an almighty
howl from the brake for the first second or so. It seems to be the salt; once it’s clean
it’s fine. The action is predictable, pleasant, and easy to modulate. The disk has not
shown an iota of rust in spite of the witches brew the highway department uses around
here.
Basically, the thing is a success. I am quite sure I did the right thing in omitting the
Travel Agent as the 2:1 step-up would double the hand pressure, and as noted, it
requires somewhat more than a caliper already. The manual calls for “a lever capable
of 24 mm of travel”, well, that’s more than a standard road setup gets you, but at least
in my case, I really don’t need it. My setup would not be tolerant of excessive slop in the
system, but that has not been a problem; the travel available is more than enough to get
the pads clear of the disk. When I squeeze, the lever pretty much stops in about half
the travel available. I have had one emergency stop (left turning car). The rig howled to
a stop no problem with plenty of travel left. One other thing: if you look at the mechanism,
I don’t see how it could use 24mm of travel at the business end. I guess the admonition in
the manual assumes some of the travel will get eaten up stretching cables and compressing
housings, and the rest is for the lawyers.
I am using the Lyra only on the front with 80 cm of wire. I use a caliper on the rear, and I
dont know if I could get away with the same trick there if I installed a Lyra there, since it
would take 140 cm of wire and there would be more spring and slop in the system. As it is
though, the front disk and rear caliper brakes seem harmonious.
When I mounted the brake, I exchanged all the bolts they sent me for stainless steel, this
is after all, a winter bike. The brake feels basically, good. The worse part is that first honk
if I pull a hard stop on a dirty day, but then back in January when the car cut me off, it was
a bonus.
Yeah, the Lyra reviews were sketchy and they are not available in the US, so ordering them here would mean an expensive return. The Aquila got better reviews and it is available in the US, but the Chain Reaction tech guy reported that it was 3mm thicker than the Lrya, so on the bubble for fitting even with Moments. I may just order a set and eat the shipping, Crow Cycles out of California has them.
I have a mountain bike that came with Tektro IO brakes. They aren’t the fanciest but they work fine once adjusted. I recently measured them at 37.5mm; I was surprised they were as thin or thinner than the Quad brake. At some point I’ll probably try to get them to work on a unicycle.
Thanks David, good to know there’s a third relatively thin mech caliper. And this one looks to be more readily available than the Quad QMD-6 or the Lyra.
Lots of reviews here at MTBR. Too many to re-post here. Nice to know there are lots of them out there, so replacement parts shouldn’t be a problem. My overall read is that they look potentially good for the relatively light braking needed on a uni; better than a V but not as strong as hydro disk caliper. I’m thinking of trying these, and if I need more power then I can always switch to a larger disc, or a hydraulic caliper (but I’d really rather avoid hydro).
Quad QMD-6 reviews?
I can’t find anything about people’s experiences with these brakes. They look OK, and they’re super cheap, but I’m not excited about being the guinea pig.
Sorry, I made a mistake above. My bike has Tektro Aquila brakes. My measurement came out narrower than reported by Chain Reaction Cycles. I measured using uniShark’s image of the Quad brake as a guide.
Hey David, that was the information I was just looking for 
The Lyra and the Aquila are similar in design, the Aquila may be lighter only due to the wave design rotors, so I was wondering how the tech at Chain Reaction had the Aquila so much wider.
There’s a dometic source for the Aquila in California (Crow Cycles). I think I’ll order a set, $75 for two complete brakes less housing and cables, pretty fair if it works.
For those who have not set up mechanical disc brakes, the single side adjustment is usually on the spoke side, the fixed side is adjusted by moving the caliper on the mount. It’s a good system, the same as is used by Avid in their BB5.
Turns out I have a Tektro IO on an old bike. I can’t find my calipers, but with a ruler looks like at least 40mm from the disk.
Aquila is looking like the best probable choice for a mechanical caliper.
For completeness, the Magura MT2 hydraulic brake is ~20mm from the disk to the crank side.