Author Topic: Rohloff Disk Brake  (Read 4545 times)

lestat_12345

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Rohloff Disk Brake
« on: May 24, 2018, 09:26:35 PM »
I'm thinking of adding a rear disk brake to my Nomad - preferably a mechanical one like the TRP. Does anyone on this forum have this setup? Is it recommended? I remember reading somewhere in one of the Thorn brochures that a disk brake can place a lot of force/strain on the frame and lead to problems as a result. I currently use a CSS rim on the back and a normal rim on the front but find braking in the wet severly lacking. I'm hoping a rear disk brake will fix this issue. I live in Scotland where it rains every other day although we have had a good spell of weather recently.

David Simpson

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Re: Rohloff Disk Brake
« Reply #1 on: May 24, 2018, 09:58:12 PM »
I do. I live in Vancouver, so same weather as Scotland, and I wanted good braking in the rain. I have a TRP Spyke brake on the rear, and it works great. (I have a Shimano V-brake on the front.)

Some mechanical disk brakes are wide, and interfere with the rack. The Spyke fits nicely. My only complain is that the adjustment screw in the center of the brake is behind my rack strut. I have a Tubus rack, not a Thorn, so it may be better with a Thorn rack. You can see the adjustment screw in this photo.
    https://www.trpcycling.com/product/spyke/
It is the small screw that is above and to the right of the main pivot. It is above the "y" in "spyke". It is the screw in the middle of the pivot, and is for adjusting the pads laterally on the disk. The small screw at above the main pivot goes through the "ears" of the pads and holds them in place. On my bike, this small screw is easily accessible.

The force on the frame caused by disk brakes is a concern for front brakes, where the fork can bend. I have not heard of any such concern for rear brakes. If it was a concern, they would not have a mounting bracket for rear disk brakes. In any case, the Nomad has an extra brace between the seat stay and the chain stay.

If you have any more questions, post them here, and I will try to answer them for you.

- DaveS
« Last Edit: May 25, 2018, 06:46:23 AM by David Simpson »

lestat_12345

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Re: Rohloff Disk Brake
« Reply #2 on: May 24, 2018, 10:08:15 PM »
It's the Spyke I was looking at. Can you recommend a 4 bolt rotor for this or will any 160mm rotor do? I bought a second hand Rohloff already built into a Mavic rim with a rotor attached.

David Simpson

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Re: Rohloff Disk Brake
« Reply #3 on: May 24, 2018, 10:16:11 PM »
Short answer: What you already have should be good.

Long answer:

Any Rohloff-specific disk should work. It needs to be Rohloff-specific, because Rohloff has a 4-bolt pattern, instead of the usual 6-bolt pattern. I'm not aware of any standard for 4 bolts, so having 4 bolts does not automatically mean it will fit the Rohloff.

I'm going by memory, but I think all disks are a standard thickness, so no issue there. The rear disk should be 160mm diameter.

- DaveS

mickeg

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Re: Rohloff Disk Brake
« Reply #4 on: May 25, 2018, 01:00:28 AM »
You are right that a frame gets a lot of stress from a disc brake.  But the Nomad frame which can take the stress of a Rohloff on the dropout should be able to take the stress.  Don't worry about it.

If you put a disc on the rear and use V brake on the front, you might consider switching your CSS rim to the front - but that would only work if both front and rear have the same number of spoke holes.

I use V brakes on my Nomad, so I can't comment on fitting of a rack on the Nomad with a disc.  But I use a disc (TRP Spyre) in the rear on my Lynskey Backroad (a titanium derailleur fitted touring bike) and a V brake (with Koolstop Salmon pads) on the front.  Thus, with both a V brake and disc brake on the same bike I can compare them.  (Simpson also has both types on one bike, as he noted.)  I find that the V brake in dry conditions seems to work a little better than the disc brake, but in wet conditions the disc brake is clearly better.  On that bike, my rim brake is not on a CSS rim.

The Spyre instructions recommended compressionless housing, which I used for most of my cable run.  I do not know if that is important or not, but I think that my brake action feels better than it would otherwise if I did not use compressionless housing.  Note that brake cable housing that is compressionless is different than shifter compressionless housing.  You cannot use shifter housing for braking, you must use brake housing.

I have never used any disc other than the TRP Spyre, so I can't compare.  But I think that the TRP mechanical brakes that actuate a pad from both sides instead the disc brake units that actuate only one side make a lot of sense.  Last month I was on a trip and someone had problems with her non-TRP brake.  I tried to adjust it so that it did not rub, it would have been a lot easier to adjust her brake if she had a TRP.

The photo is of my Spyre on my Lynskey.  It is mounted on the chainstay, not the seatstay like on the Nomad.  Thus, I have no clue if your rack would fit with that brake or not.  And if you could put both the brake and rack on the bike, would the rack interfere with your ability to adjust the brake?


PH

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Re: Rohloff Disk Brake
« Reply #5 on: May 25, 2018, 03:11:05 AM »
I have a Spyre on the rear of my mercury, it works fine. Though I'd agree with this from DaveS
Quote
Short answer: What you already have should be good.
Particularly as most of your braking ability is from the front wheel - with the same brake the stopping distance from rear only would be twice that of front only, and the fastest way to safely stop a bike is with a front brake hard enough to be close to lifting the rear wheel.   However much you were to improve the rear braking it isn't going to be a great improvement on the overall stopping ability and IMO it'd better to find ways to improve that. 

David Simpson

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Re: Rohloff Disk Brake
« Reply #6 on: May 25, 2018, 06:08:13 AM »
Sorry, my comment was ambiguous. When I said that what he had was good, I meant the disk that he had should work.

I agree that in dry conditions, V-brakes will be as good at stopping as disk brakes. But in the wet, I have found disk brakes to be much better than rim brakes.

- DaveS

David Simpson

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Re: Rohloff Disk Brake
« Reply #7 on: May 25, 2018, 06:47:35 AM »
In a previous post (reply #1 in this thread), I was wrong about the adjustment screw. I have corrected that post above.

- DaveS

martinf

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Re: Rohloff Disk Brake
« Reply #8 on: May 25, 2018, 07:21:43 AM »
I'm thinking of adding a rear disk brake to my Nomad.

Not yet had disk brakes (I have in the past used coaster brakes, and currently have rear roller and drum brakes respectively on two family bikes). An advantage of non-rim brakes is less muck sprayed off the rims and onto the chain, this is not relevant if using a Chainglider.

The rear brake is less effective than the front, so for better wet-weather performance you might also need to improve the front. I find Koolstop Salmon brake pads (V-brakes) or Aztec brake pads (cantilever brakes) work well enough for me on non-CSS rims.

CSS rims have been reported to be less effective than normal rims in the wet. I have CSS front and rear on my Raven Tour, but have not yet had any issues.

PH

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Re: Rohloff Disk Brake
« Reply #9 on: May 25, 2018, 10:36:41 AM »
Sorry, my comment was ambiguous. When I said that what he had was good, I meant the disk that he had should work.
Ahh, my misunderstanding. 
My point still remains - that the rear brake has little impact on stopping distance compared to the front, assuming the limiting factor is the contact with the surface, off road different rules apply!
This might be worth a read;
http://sheldonbrown.com/brakturn.html

lestat_12345

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Re: Rohloff Disk Brake
« Reply #10 on: May 28, 2018, 11:59:05 AM »
Can anyone tell me if a Rohloff hub wheel that uses a disk brake needs to be dished? Also, will the TRP Spyke disk brake work with Shimano deore v-brake levers?

PH

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Re: Rohloff Disk Brake
« Reply #11 on: May 28, 2018, 12:49:00 PM »
On the first point I would say probably not dished.  Mine has been converted and the hub shell with both flanges hasn't been changed, also the online spoke calculator I use only has one Rohloff option and that has equal spoke lengths.  Those two things make me 99.9% certain...
On the second point, I'm 100% they work fine together as those are the levers and brake I'm using.

David Simpson

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Re: Rohloff Disk Brake
« Reply #12 on: May 28, 2018, 03:12:56 PM »
Yes, I can also confirm it. I built a wheel using a disk Rohloff, and there is no dish. All of the spokes have the same length. And I am using a TRP Spyke brake with Shimano Deore v-brake levers.

- DaveS

mickeg

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Re: Rohloff Disk Brake
« Reply #13 on: May 28, 2018, 03:43:17 PM »
In my previous post I suggested you consider moving your CSS rim to the front, but if that rim has Rohloff drilling and your front rim does not, that was a bad suggestion on my part - disregard it.

PH

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Re: Rohloff Disk Brake
« Reply #14 on: May 28, 2018, 03:58:53 PM »
I'm still of the opinion that before spending money on the rear brake doing everything possible to maximise the front braking would be time and money better spent.