What disc brake post mounts would I need?

[Deleted member 22722]

I'll be taking delivery of a new Cannondale Synapse Disc in a few weeks time. The Mavic Aksium wheels that come supplied with it are centrelock compatible and have 140mm rotors.

I've also purchased a set of lighter wheels that I intend to use with this bike. The problem is that they are 6-bolt rotor compatible. I am struggling to find any rotors that are 6-bolt compatible in size 140mm. Can anyone recommend any that will work ok with Shimano RS685 hydraulic calipers? The recommendation is to use the Shimano RT99's but these don't seem to be available as the 6-bolt variety.

I am guessing that it may be easier to just move up to 160mm rotors. However if I do that I think i'll need to change the size of the post mounts to accommodate the difference in rotor size, correct? I think i'll need a 20mm post adapter but does anyone know what type of adapter i'll require for the synapse ie. Post to Post, Post to IS, Flat mount etc

Thanks in advance.

 

[Yellow Saddle]

I guess you're from the UK so let me get my hobby horse out of the way first. Those discs on your disc brake bikes are called....discs.

You get adapters that go from 6-bolt to centre lock. That's one route.
The route of putting larger discs on is another but they are really over the top for a road bike application other than alpine use for heavy riders or loaded touring.

If you change discs, keep in mind that there are two broad types, resin-compatible only and metallic and resin compatible. Better brake pads are metallic (sintered metal) and requires a harder, more expensive disc. You can use the softer resin pads on them but you can't use metallic pads on resin-only discs. Although you can change pads, that is yet another expense to consider.

As for the type of adapters you need, only someone with a Synapse in front of them or intimate knowledge can tell you that. There will be lots of them here.

 

[Deleted member 22722]

You get adapters that go from 6-bolt to centre lock. That's one route.

Cheers for your response.

From what I've seen those 6-bolt to centrelock adapters are for converting 6-bolt discs to allow them to fit to centrelock hubs. I need it the other way around. I need to fit a centrelock disc to a 6-bolt hub. I'm not sure if these type of converters exist.

The 160mm discs may be unnecessary on a road bike but if it allows me to use my new wheels on the new bike I can live with that.

 

[Sea of vapours]

I think this is the right 'direction' of adapter you need?

http://www.ebay.co.uk/itm/New-ALLIG...563224?hash=item259ed53698:g:upkAAOSwYGFUyazc

 

[Milkfloat]

You want cheap http://www.ebay.co.uk/itm/like/252196674858
or good http://www.tweekscycles.com/components/brake-rotors/hope-technology-trial-zone-rotor ?

 

[Deleted member 22722]

I think this is the right 'direction' of adapter you need?

http://www.ebay.co.uk/itm/New-ALLIG...563224?hash=item259ed53698:g:upkAAOSwYGFUyazc

Unfortunately that adapter is still the wrong way around. That adapter will allow a centrelock hub to be converted to take a 6-bolt disc.

I have a 6-bolt hub that I'd like to fit a centrelock disc to.

Cheers

 

[Deleted member 22722]

You want cheap http://www.ebay.co.uk/itm/like/252196674858
or good http://www.tweekscycles.com/components/brake-rotors/hope-technology-trial-zone-rotor ?

Cheers for that. I'd rather pay for quality components so will investigate the Hope discs as it does seem that they offer quite a few 6-bolt discs in the 140mm size. I've contacted Tweeks to ask if these will be compatible with the Shimano RS685 calipers just in case there are likely to be any clearance issues etc.

Thanks

 

[Sea of vapours]

I have a 6-bolt hub that I'd like to fit a centrelock disc to.

Yes, that's what I understood. Are you quite sure that the linked adapter won't do that? Looking at it (again) it appears to have the five bolt locations on the wheel side and the away-from-wheel side appears to be a centre lock adapter ring onto which the centre lock disc would fit. i.e. the lock ring part would sit on top of and hold the centre lock disc, with the five bolt part being bolted to the five bolt hub.

 

[Tojo]

Here are some 140mm rotors............http://www.discobrakes.com/?s=0&t=4&c=55&p=186

 

[Deleted member 22722]

Yes, that's what I understood. Are you quite sure that the linked adapter won't do that? Looking at it (again) it appears to have the five bolt locations on the wheel side and the away-from-wheel side appears to be a centre lock adapter ring onto which the centre lock disc would fit. i.e. the lock ring part would sit on top of and hold the centre lock disc, with the five bolt part being bolted to the five bolt hub.

Yes, there's an expanded image showing the centrelock adapter sitting between the centrelock hub and 6-bolt rotor.

 

[lpretro1]

be careful - have found on some frames the use of such an adapter puts the disk too close to the fork/frame - they are often very close tolerance. Same with going up a rotor size - you may find it cannot take a bigger rotor