Rear disc brake conversion?

[Ubert767]

Can anyone advise on the conversion from worn CSS rim  "V" brakes to a rear disc brake on a Rohloff hubbed Mk1 Raven Nomad, please?
Rob

[PH]

I'm not sure what bike you have?  To convert to a disc brake the frame needs to have that fitting and the Raven didn't.

[Ubert767]

Hello PH,
As far as I'm aware my bike frame does have the necessary rear  braze-ons to accommodate a disk caliper, it's a 2007 MK1 Rohloff equipped Nomad.
Rob

[PH]

In that case - first see if the hub is disc ready or the rim brake version, some people chose to have that hub even with rim brakes to future proof it.  If not it needs the shell cap replacing which is a workshop job.  Then if it's an internal shift mech it needs converting to external (Can't fit a disc with an internal), you can do that yourself with the parts, but if you're sending it off for the cap you may as well have that done in the workshop. Cost of those two items was around £350 seven years ago, don't know what the current price would be.  Then of course you have the cost of the rotor and brake, plus the frame may need facing. Then it's just the wheelbuild. 
I went through it when I put the hub that originally came on my Raven, into a Mercury frame, SJS did the work.  If I had my time again I think I'd have sold the hub and bought a disc version new, there wouldn't have been much difference to the cost.

[Chris667]

I know this isn't what you are asking, but I have always felt a disc brake was more useful on the front, if at all.

[PH]

I know this isn't what you are asking, but I have always felt a disc brake was more useful on the front, if at all.

From a purely braking perspective, you're probably right, my folder has a better brake on the front than the back and it stops well.  But there are other considerations, if you want a lighter more flexible fork, that's more achievable with rim brakes and importantly for a Rohloff, if you want to avoid disturbing it for wheel builds a disc brake avoids the wear.   

[martinf]

Nothing to do with braking as such, but a rear wheel disc brake (or drum, roller or coaster brake) doesn't spray muck and water from the rim and onto the chain like a rim brake can.

Not much off an issue with a Chainglider, but it has made a difference on two of my bikes. Combined with a low hanging front mudflap to reduce spray from the front wheel.

[mickeg]

My Rohloff is on a rim brake bike and I have no plans to convert it.

One reason is that some rear Rohloff hubs with disc brakes have had oil leakage onto the rotor.  I say that based only on what I have read on this and one other bike forum. 

My point is that if you make the conversion, do your best to make sure that you have very good seals on your Rohloff to avoid any oil contamination on the rotor.  My Rohloff is one that I suspect would have a lot of contamination on the  rotor.

If you convert to a different rim, do not discard the CSS rim, those rims can't be obtained any more and I am sure someone would love to have it.

[in4]

I’ve had a rear css rim for 6 years now. The braking advantage remains good and much better than a non css rim.
The thought occurred how long a css rim is likely to last and if at some point  it would be necessary to fit a rear disc brake.

[PH]

I’ve had a rear css rim for 6 years now. The braking advantage remains good and much better than a non css rim.
The thought occurred how long a css rim is likely to last and if at some point  it would be necessary to fit a rear disc brake.

I have just one left in use, a 700c front dynamo wheel, it's been on three bikes since I think 2007, conservative estimate of mileage would be 80,000, the bulk of that while it was on commuting bikes.  It's currently on the Mercury and doing no more than 3,000 miles a year and less likely to be used in poor weather. it started life as almost 2mm thick and is currently 1.3, I'd expect it to be fine to 0.8. For me, that'll be another 20 years, there's a good chance of it outlasting me, or at least my cycling days.