We did a long mountain descent on our Ventana ECdM MTB Tandem (descending 1000m over 7km on offroad trails). I noticed some plinking noises after the descent and realised it was the vented front rotor cooling down. The video below is a little recording of the noise. Our MTB tandem has the Hope Tech Evo V4 calipers front and rear with a Hope floating vented 203mm rotor on the front and a fixed Rohloff 203mm rotor on the back. When purchased I was told that we couldn’t have the V4 floating disc on the back as the Rohloff hub only allows rotors with with a 4 bolt attachment pattern (standard for normal hubs is 6 bolt).
The brake setup has performed pretty well but it is a shame we can’t have the vented disc on the back wheel as well; the vented disc definitely gives more reliable stopping power on a long descent over the non-vented disc. We are also getting a loud resonance noise from the rear brake when it is applied for more than a few seconds.
Update: 13th November 2013
I have been investigating rear brake options and have found that there is a 4 bolt version of the Hope V2 vented rotor. I am finding out if this will work with the V4 calipers. If it will work I plan to update the rear fixed rotor with the floating vented Hope version to see if it fixes the noise and fade issues we currently get with the rear rotor on long steep off road descents. The part number for the Hope V2 rohloff specific floating vented rotor is HBSP196:203:4R
Images below show the difference between the V2 and the V4 rotors (and the difference between the Rohloff 4 bolt and Standard 6 bolt fixings)
As you’re in the UK… pop a nice email to Hope and they’ll probably make a V4 vented rotor with a Rohloff bolt-pattern. A V2 one would work mind… just not look at pretty as a V4 one plus there’d be unused brake-track. Heh.
I had already ordered the V2 one when I saw this. Good idea though. If the V2 version fails (seems unlikely as it is pretty chunky) I will try this.