Author Topic: Rohloff Disk Brake  (Read 2282 times)

lestat_12345

  • Newbie
  • *
  • Posts: 49
Re: Rohloff Disk Brake
« Reply #15 on: May 28, 2018, 04:09:42 PM »
Well I've got XT brakes on the front using salmon pads. But I feel that using these to brake in the rain, combined with my rear CSS rims, is severely lacking - especially downhill and fully loaded.
« Last Edit: May 28, 2018, 04:36:18 PM by lestat_12345 »

mickeg

  • Hero Member
  • *****
  • Posts: 1552
Re: Rohloff Disk Brake
« Reply #16 on: May 28, 2018, 09:31:54 PM »
I assume you mean the Koolstop Salmon pads, I can't think of anything better on a regular (non-CSS) rim.

***

I assume you have not invested anything into this project yet.  So, I will mention one other option for you to compare prices on.  There now is an Nomad fork that can take a disc brake. 
https://www.sjscycles.co.uk/forks/48-26-650b-thorn-nomad-disc-fork-yellow-gloss/?geoc=US
https://www.sjscycles.co.uk/forks/48-26-650b-thorn-nomad-disc-fork-matt-black-powder/?geoc=US

Thus, you could leave your Rohloff hub untouched and keep using rim brakes on your rear CSS rim.  You I assume would need a new front hub, you could avoid buying the special four bolt Rohloff disc and use a standard disc, new spokes for the front wheel, maybe the cost to build up a new wheel on either your existing rim or a new rim, etc.  I have no idea if you use a dynohub or not, etc.

I do not know which would cost more, the disc on front or disc on rear, but you might want to do that research.

If you replace the fork, you might want to get a new crown headset race installed on the fork before they ship it to you.  You would also need a new star nut.  And, I have no idea if you would need to cut the steerer tube or not.


PH

  • Hero Member
  • *****
  • Posts: 641
Re: Rohloff Disk Brake
« Reply #17 on: May 29, 2018, 02:49:23 AM »
Well I've got XT brakes on the front using salmon pads. But I feel that using these to brake in the rain, combined with my rear CSS rims, is severely lacking - especially downhill and fully loaded.
Which makes it all the more puzzling, I have the same brakes, pads and Deore levers - I'm 95 kg and often carrying luggage.  I don't know what to suggest, having swapped components from a bike with Vs on both wheels to V front and disk rear, there hasn't been any noticeable reduction in the stopping distances.

martinf

  • Hero Member
  • *****
  • Posts: 569
Re: Rohloff Disk Brake
« Reply #18 on: May 29, 2018, 08:26:37 AM »
I'd second George's idea for front disc brake rather than rear if you need more rapid wet-weather braking. Or go the whole hog and fit discs front and rear. Personally, I find the factor that limits braking is tyre adhesion.

Cantilever front and U-brake rear (both rim brakes) were quite sufficient for me with an all-up weight of about 115 kg on wet mountain descents in the Picos d'Europa, but I expect discs would have had a much quicker response in the wet (lock the wheel quicker).

I had two braking issues on that tour. First issue was having to stop and wait to cool the rims on long, twisty descents, when it wasn't possible to go fast and use wind resistance as a brake (IIRC I had to stop twice in 3300 kms). This only happened in dry conditions as heavy rain water-cools the rims. The other issue was the muck sprayed off the rear rim getting onto the chain, this happens with all rim brakes but is even worse with a U-brake.

I don't think there is an easy solution to the first issue (discs can also overheat). I solved the second issue on my current touring bike by fitting a Chainglider.

geocycle

  • Hero Member
  • *****
  • Posts: 1157
Re: Rohloff Disk Brake
« Reply #19 on: May 29, 2018, 09:39:23 AM »
Well I've got XT brakes on the front using salmon pads. But I feel that using these to brake in the rain, combined with my rear CSS rims, is severely lacking - especially downhill and fully loaded.
Which makes it all the more puzzling, I have the same brakes, pads and Deore levers - I'm 95 kg and often carrying luggage.  I don't know what to suggest, having swapped components from a bike with Vs on both wheels to V front and disk rear, there hasn't been any noticeable reduction in the stopping distances.

The CSS rim braking thing is a mystery.  There are lots of reports of problems in the wet but I really haven't ever experienced anything untoward.  I recently replaced my front rim with a standard grizzly and I am already on the second set of pads.  When this wears I'll go back to CSS on front and back.  If disks were available I probably would try them although I would not expect a great improvement.
 

Andre Jute

  • Hero Member
  • *****
  • Posts: 3150
Re: Rohloff Disk Brake
« Reply #20 on: May 29, 2018, 09:48:48 AM »
Martin is right: Under any and all circumstance the friction between the tyre and the road determines and limits braking power.

Furthermore, I'd be most surprised to discover even one rear disc brake/front whatever other brake that is more effective than rim brakes all round; the rear brake takes care of perhaps 20% of braking, and that would be under the most favourable circumstances; normally it would contribute less, usually only keeping the bike straight and the rear wheel from overtaking the front. It seems to me a disc only on the rear wheel, unless it solves some other problem, typically on converted bikes, is likely to be wasted.

***
A couple of other braking options that are sometimes overlooked:

a) Shimano's roller brakes are a killer option. I don't know what model number they're up to now, but I have the -70 series roller brakes on my Trek Smover bike and they're as good as discs, except better in that nothing can splash on them because they're fully enclosed. Personally, I hate disc brakes and roller brakes both because they demand too much of my attention under threat of a faceplant through too-sudden braking, but there is no doubt in my mind that both offer tip-top braking. The Shimano roller brakes are compatible with Shimano hub dynamos and their reaction arm attaches to standard disc brake fork-side fittings. A novel use of earlier, weaker Shimano roller brakes is to fit the modern hugely effective roller brake on the front wheel, and an earlier series (I used the -41) on the rear for a very agreeable form of anti-skid braking, though you cannot do this on a Rohloff-equipped bike as there are no roller brakes that will fit a Rohloff's four disc bolts. Roller brakes require a service of a special grease squeezed in through a nipple on the outside which can be usefully combined with the Rohloff oil change and EXT click box service.

b) Having said that, on my current daily bike, which I've kept longer than any other bike, I have the biggest hydraulic disc brakes you can fit, front and rear. They're a full 622mm, over two feet across, near enough rim size. They're misnomered Magura Hydraulic Rim Brakes, they're sealed for life, they're never serviced though rebuilding parts and fluids are readily available if you can be bothered (the rebuilding parts and fluids add up to around half the street price of simply fitting brand-new when the old ones suffer some incident; like a Rohloff, they don't seem to wear out). The great thing about the Magura Hydraulic Rim Brakes is that the ones that fit touring bikes once upon a time came in two versions with different size chambers. I deliberately specified the weaker version for more progressive braking; I've never once wished for stronger brakes. (When the usual testorone-for-brains jerks on a bike tech conference I belong to sneered and screeched about how real men need the biggest, harshest brakes imaginable, a famous bike mechanic remarked that actually mine were the biggest disc brakes: full rim size.) As a small bonus, the Magura rim brakes are very economical on brake blocks, and your rims too. If your bike has the fittings for the Magura Hydraulic Rim brakes (if you"re lucky, it's a straight swap for the non-hydraulic fitted brake), I highly recommend them for touring bikes as a perfect, service and glitch free component. BTW, you can buy the cheaper version (HS11) with confidence. Technically it is the same as the more expensive version, just presented differently (and I think more attractively), as Magura no longer offers two chamber sizes in that line. The last time I looked there were several other types of the Magura Hydraulic Rim Brakes for different niches, including some with greater clamping force; if you consider these, you need to pay careful attention to the tyre width it will fit over. If you want to adjust the clamping strength of the touring type it is easily done by fitting or removing the so-called "brake booster", which is an upside-down U-shaped device for reacting brake torque before it gets to the fork; I specified my bike without; if your daily commute is over the Alps, by all means fit it, but for normal riding it is dead weight (if men can self-identify as women, I can self-identify as a weight weenie!). Magura's rim hydraulics are sold singly or in pairs at a saving over buying two singles; front and rear brakes differ only in the length of prefilled tubing and each is fully-selfcontained.

lestat_12345

  • Newbie
  • *
  • Posts: 49
Re: Rohloff Disk Brake
« Reply #21 on: May 29, 2018, 12:56:09 PM »
I did look at the Magura Hydraulic Rim Brake but I read somewhere that these will not fit on the Nomad. Maybe I'm mistaken but I'm sure it was someone from SJS/Thorn, on this forum, that said this.

martinf

  • Hero Member
  • *****
  • Posts: 569
Re: Rohloff Disk Brake
« Reply #22 on: May 29, 2018, 01:09:37 PM »
Shimano's roller brakes are a killer option.

I have about 7000 kms of experience with Shimano roller brakes on rear wheels, and currently have one on my large visitor bike, where it has replaced the U-brake, a roller brake was the only other option when using a Nexus Premium 8 hub gear on this bike.

My take on roller brakes (I have the older BR-IM41 and BR-IM50 models) :

- as for all hub brakes, cleaner than rim brakes and less affected by wet conditions.
- useful on some small wheel bikes, I found rim brakes were borderline on the old Moulton 16" wheel bikes I used to have - coaster, drum and roller brakes worked much better.
- I don't like the feel - the roller brakes I have used seem a bit all or nothing, even when regularly greased with the recommended special Shimano grease. So I wouldn't want to have one on the front wheel.
- no good for hilly touring. On long hills the brake gets hot and melts the grease, which then runs down the spokes.

Not relevant for hilly touring or Rohloff use, but my favourite non-rim brake is a drum brake. I still have one on the rear of the small visitor bike (but due to be replaced soon by a Thorn Raven Tour Step Through with modern V-brakes). I find Sturmey-Archer drum brakes are less harsh than roller or coaster brakes, more or less completely unaffected by weather, and require virtually no maintenance. The larger Atom drum brake I once had on a tandem worked similarly.

PH

  • Hero Member
  • *****
  • Posts: 641
Re: Rohloff Disk Brake
« Reply #23 on: May 29, 2018, 01:43:39 PM »
I did look at the Magura Hydraulic Rim Brake but I read somewhere that these will not fit on the Nomad. Maybe I'm mistaken but I'm sure it was someone from SJS/Thorn, on this forum, that said this.
Yes, answering your question!
http://thorncyclesforum.co.uk/index.php?topic=12451.0

I had them on my Raven for a while, good brakes but couldn't stop them squealing and when I changed to CSS rims there weren't the appropriate pads available.

When I built up the Mercury, I used compression-less cable on the front V brake (the off cut from the one on the rear disc) mainly to have matching cables but I'm pretty sure it also improves the braking slightly.   
I don't want to sound like I'm trying to teach anyone to suck eggs, but care taken getting the cable cuts perfect is worth while as are good quality ferrules, more so than many people realise.   I've improved the braking on new bikes by re-doing it! I also set my brakes with good clearance, this gives more movement in the levers before the brakes engage than is usual, not enough for the levers to come back to the bars but not far short.  Hands are naturally stronger at that point, the only minor disadvantage is that they require more frequent adjustment.
« Last Edit: May 29, 2018, 01:45:23 PM by PH »

lestat_12345

  • Newbie
  • *
  • Posts: 49
Re: Rohloff Disk Brake
« Reply #24 on: May 29, 2018, 04:50:31 PM »
My bad PH, I realised I had a previous post regarding the Magura's after I made my last comment. I'm getting old and the memory ain't as good as it was.

Andre Jute

  • Hero Member
  • *****
  • Posts: 3150
Re: Rohloff Disk Brake
« Reply #25 on: May 29, 2018, 10:30:53 PM »
...getting old and the memory ain't as good as it was.

You're not the only one. Now that Paul has told us, I too remember that post last year... Apologies for sending your thread off in the wrong direction.

PH

  • Hero Member
  • *****
  • Posts: 641
Re: Rohloff Disk Brake
« Reply #26 on: May 30, 2018, 03:14:09 AM »
...getting old and the memory ain't as good as it was.

You're not the only one. Now that Paul has told us, I too remember that post last year... Apologies for sending your thread off in the wrong direction.
My memory isn't any better than anyone else's, I was interested to see if the subject had come up before and did a search...
I also have a vague memory of there being another reason Thorn discouraged the use of maguras, but I can't find anything to substantiate it so I could be wrong.
 

martinf

  • Hero Member
  • *****
  • Posts: 569
Re: Rohloff Disk Brake
« Reply #27 on: May 30, 2018, 09:07:19 PM »
I also have a vague memory of there being another reason Thorn discouraged the use of maguras, but I can't find anything to substantiate it so I could be wrong.

I think it might be because repairing hydraulics on a world tour is more difficult than replacing a V-brake cable. Which is one of my own reasons for not having Magura rim brakes or (any) disc brakes on a touring bike.

I don't do expedition touring, but I reckon I could get repairs, workable spares or replacements for most of my bike components fairly easily in most small towns in the areas where I have toured, with the one notable exception of the Rohloff hub. The latter is supposed to break very infrequently, and Thorn/Rohloff seem to have a pretty good reputation of getting spares to remote places in a fairly short time.

mickeg

  • Hero Member
  • *****
  • Posts: 1552
Re: Rohloff Disk Brake
« Reply #28 on: May 31, 2018, 03:26:10 AM »
The sign says you can't buy fuel for your car or truck for 205 km, and if you can't buy motor fuel you certainly can't buy much else.

I never saw a bike shop when I did my Iceland tour.  But I met several people that were limping along on bikes that had some form of difficulty.  I agree with MartinF in that I would never use hydraulics on a tour either.


PH

  • Hero Member
  • *****
  • Posts: 641
Re: Rohloff Disk Brake
« Reply #29 on: June 04, 2018, 11:04:23 PM »
I was reminded of this thread today whilst walking a loaded bike down a steep ramp - apply the rear brake and the wheel just locks and the bike keeps moving, apply the front and I could stop the bike in an instant.  Yes of course the dynamics are different, but I believe the principle is the same.