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Help with disc brakes

Old 12-03-17, 01:03 PM
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Yossarian22
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Help with disc brakes

I'm building up a new Ti frame bike that is configured for cable shifters and disc brakes. Most of the hardware is pretty straightforward, except for brakes, where there seems to be quite a few types and mounting systems.

The frame was sold to me as a post mount, however, when I got it, I saw that the brake mounts, located on the seatstay, are not threaded and measure about 51mm. A quick net search indicates that this means IS type. I'd like to do an Ultegra build with ST-RS685 cable shifters and BR-RS785 hydraulic calipers. The brakes are only available as post-mounts however. Another internet search seems to indicate that post mount will work, but requires a 51 to 74mm IS to post adapter. Is that the case?

Apologize in advance for the newbie questions. I'd like to think that I'm a pretty competent shade tree mechanic: I've rebuilt a number of older bikes and do nearly all my own repairs as well. While I'm familiar with motorcycle disc brakes, from replacing rotors to bleeding hydraulic systems, I'm brand new to bicycle disc brakes and am trying to make sense of IS, post and flat mounts, and CLD and XLR hubs to boot.
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Old 12-03-17, 01:33 PM
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JonathanGennick 
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What is the frame? Can you link us to the specs online?
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Old 12-03-17, 02:31 PM
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Yossarian22
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It's a Lynskey Urbanskey, new but a 2014 model. There's no longer anything on the factory website since it's been replaced by the Urbano, but there are still leftovers on Lynskey's ebay web site that should have the specs and definitely show the mount. I'm a new member, so can't yet post links.
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Old 12-03-17, 02:41 PM
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dsaul
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You need an IS to Post Mount adapter. They come in different sizes depending on what size rotor you will be using and whether it is on the front or rear. I don't think anyone has actually made an IS mount caliper in a great number of years, but IS mounts are pretty standard on frames.
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Old 12-03-17, 03:43 PM
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I concur w/dsaul. Here's a link to a Shimano-branded adapter that will support a 160 mm rotor on the rear:

Shimano 160mm Is Disc Brake Adaptor | Jenson USA

Take note that the adapter that you would use to put a 160 mm rotor on the rear is going to support a 180 mm rotor on the front. For example, here is the front version of the above part:

Shimano 180mm Is Disc Brake Adaptor | Jenson USA

Good luck with your build. I did find the frame on eBay. Looks nice. And titanium! That's good stuff.
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Old 12-03-17, 07:13 PM
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Yossarian22
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Originally Posted by JonathanGennick View Post
I concur w/dsaul. . . .

Take note that the adapter that you would use to put a 160 mm rotor on the rear is going to support a 180 mm rotor on the front. . .
Good luck with your build. I did find the frame on eBay. Looks nice. And titanium! That's good stuff.
Thanks for the help and to dsaul as well.

I demoed a Roubaix at RAGBRAI this past summer and got the bug for an endurance/sportive bike. I had been demoing Synapse and Domane when a fellow cyclist suggested that consider a Ti frame. I found a Litespeed at a local shop and that ride impressed me enough to do some more digging on titanium frames. I soon found that Lynskey got rid of their older stock through their factory eBay site and was seduced into bidding by the attractive price. I put a bid in at $10 over the minimum asking price and "won" the frame (in truth, I was the only bidder and there was no reserve). I was very impressed when I opened the box and saw the frame - the weldments are some of the best torch work I've seen.

Since you mention rotors (again thanks - you help clear up another point of confusion regarding sizing for adapters), let me ask a related question. What rotor size would you recommend? The Urbanskey will see an occasional fire road and gravel loop, but will primarily be ridden as an endurance bike. I don't think I'll often need the improved braking that 160mm rotors can provide but since the weight penalty for them is fairly small, it may make more sense to go with them rather than 140mm.

And another related question, this time about hubs. I will be having a wheelset built up and am leaning toward CLD hubs. I know this drives a TA system, but the Urbanskey can do either QR or TA so I'm good there, though I will need to get the adapters as the frame comes with QR. I'm probably going with a Lynskey gravel fork which takes a 15 x 100mm TA. It's my understanding that CLD is more flexible in that you can use 6 bolt with a CLD hub and adapter, but not the reverse. Any reason not to use center-locks?

As I said, this is all new to me so any advice is appreciated.
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Old 12-03-17, 07:15 PM
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Originally Posted by JonathanGennick View Post
I concur w/dsaul. . . .

Take note that the adapter that you would use to put a 160 mm rotor on the rear is going to support a 180 mm rotor on the front. . .
Good luck with your build. I did find the frame on eBay. Looks nice. And titanium! That's good stuff.
Thanks for the help and to dsaul as well.

I demoed a Roubaix at RAGBRAI this past summer and got the bug for an endurance/sportive bike. I had been demoing Synapse and Domane when a fellow cyclist suggested that consider a Ti frame. I found a Litespeed at a local shop and that ride impressed me enough to do some more digging on titanium frames. I soon found that Lynskey got rid of their older stock through their factory eBay site and was seduced into bidding by the attractive price. I put a bid in at $10 over the minimum asking price and "won" the frame (in truth, I was the only bidder and there was no reserve). I was very impressed when I opened the box and saw the frame - the weldments are some of the best torch work I've seen.

Since you mention rotors (again thanks - you help clear up another point of confusion regarding sizing for adapters), let me ask a related question. What rotor size would you recommend? The Urbanskey will see an occasional fire road and gravel loop, but will primarily be ridden as an endurance bike. I don't think I'll often need the improved braking that 160mm rotors can provide but since their weight penalty is fairly small, it may make more sense to go with them rather than 140mm. Your thoughts?

And another related question, this time about hubs. I will be having a wheelset built up and am leaning toward CLD hubs. I know this drives a TA system, but the Urbanskey can do either QR or TA so I'm good there, though I will need to get the adapters as the frame comes with QR. I'm probably going with a Lynskey gravel fork which takes a 15 x 100mm TA. It's my understanding that CLD is more flexible in that you can use 6 bolt with a CLD hub and adapter, but not the reverse. Any reason not to use center-locks?

As I said, this is all new to me so any advice is appreciated.
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Old 12-03-17, 07:40 PM
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JonathanGennick 
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Originally Posted by Yossarian22 View Post
Since you mention rotors (again thanks - you help clear up another point of confusion regarding sizing for adapters), let me ask a related question. What rotor size would you recommend? The Urbanskey will see an occasional fire road and gravel loop, but will primarily be ridden as an endurance bike. I don't think I'll often need the improved braking that 160mm rotors can provide but since the weight penalty for them is fairly small, it may make more sense to go with them rather than 140mm.
I'd probably go 160 front/rear just because it's a common size and easy to find. I sort of see it as a default.

Years ago I once tried 140 rear and 160 front on my Salsa Fargo. I didn't really like the 140 in back. It felt just a little bit too wimpy.

And another related question, this time about hubs. I will be having a wheelset built up and am leaning toward CLD hubs. I know this drives a TA system, but the Urbanskey can do either QR or TA so I'm good there, though I will need to get the adapters as the frame comes with QR. I'm probably going with a Lynskey gravel fork which takes a 15 x 100mm TA. It's my understanding that CLD is more flexible in that you can use 6 bolt with a CLD hub and adapter, but not the reverse. Any reason not to use center-locks?
I ended up with a center-lock hub for the first time ever this summer because of a wheel that I bought premade that just happened to come that way. You won't go wrong either way, but I sure did enjoy the ease of installing that centerlock rotor. FWIW, I am pretty sure you can get a centerlock rear hub that is QR. Definitely go TA in front though.
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