[denjen]

I just got a 2012 Specialized Stump Jumper EVO that came with post mounts for the rear brake. Getting ready to put a set of Magura Louise brakes with 180mm rotors front and rear on it. I can find the front post mount adapter no problem, but cant find the rear adapter anywhere. Is the adapter the same for front and back if it is post mount? Or does anyone know the correct part number I need?

Thaks for the help

 

[jonKranked]

who the eff puts post mount on a frame? unheard of.

 

[jonKranked]

to answer your question, i'm guessing that a front post mount would work for the rear... try it and find out.

 

[IH8Rice]

who the eff puts post mount on a frame? unheard of.

plenty of mfg's are using it now

 

[jonKranked]

plenty of mfg's are using it now

why? what's the benefit?

 

[denjen]

who the eff puts post mount on a frame? unheard of.

Specialized, did you even bother to read my whole post?

why? what's the benefit?

I guess it eliminates the need for an adapter if you are using a 6" rotor.

 

[IH8Rice]

why? what's the benefit?

no adapter needed typically.
and of course, another "standard." but this one actually makes sense

spesh and c'dale are the first two that pop into my head that use it. i know several others do too.

 

[descente]

if its PM160 which i'm pretty sure it is, then you can use the same adapter for a front 180 to PM. the bikes specialized is shipping come with some spacers that serve the same purpose and save even more weight.

 

[gonefirefightin]

bottle of bacardi and JB weld

 

[denjen]

if its PM160 which i'm pretty sure it is, then you can use the same adapter for a front 180 to PM. the bikes specialized is shipping come with some spacers that serve the same purpose and save even more weight.

Thanks for the info. I will have to dig through the box of extra stuff I got from specialized to see if those spacers are in there

 

[oldfart]

PM front and rear makes sense to eliminate different front and rear calipers. IS rear with a post front is dumb. And centering IS can be a pain in the arse too compared with a simple post mount. And eliminate a rear adapter if you are going to use a rotor that does not require an adapter.

I would think descente is correct.

 

[sanjuro]

I wonder if the SJ Evo is designed for a 160mm rotor, which then the post mount is designed for mounting a brake without an adapter.

I know it is not what you want to do, but you much better off using a 160mm rotor. I'm sure getting a Magura compatible 6 inch rotor is much, much easier than a 180mm post-to-post adapter.

But I will also argue that a 160mm rear rotor is more than adequate. I'm over 200lbs, and one time I rode a hardtail with a 140mm rear rotor, which I didn't notice until the owner mentioned it to me about 6 miles into the ride.

 

[denjen]

I wonder if the SJ Evo is designed for a 160mm rotor, which then the post mount is designed for mounting a brake without an adapter.

I know it is not what you want to do, but you much better off using a 160mm rotor. I'm sure getting a Magura compatible 6 inch rotor is much, much easier than a 180mm post-to-post adapter.

But I will also argue that a 160mm rear rotor is more than adequate. I'm over 200lbs, and one time I rode a hardtail with a 140mm rear rotor, which I didn't notice until the owner mentioned it to me about 6 miles into the ride.

I agree a 6" rotor is more than enough for most of the riding I do. This is my only bike though, so it has to do everything I am planning on doing, from XC riding to several weekends a year doing DH runs at a resort.

 

[sanjuro]

I'll still argue that a 6 inch rotor will be adequate for even DH (and an 8 inch rotor in the front is way more important).

Put it this way, in DH you will put the brakes on heavy on high speed descents, which means you will be transferring your weight to the front wheel.

Even if you were to lock up the back wheel in a tech section, not only is it controllable, it might be a desired effect.

 

[sanjuro]

PS I guess heat dissipation is better with a larger rotor.

 

[oldfart]

PS I guess heat dissipation is better with a larger rotor.

It is and if your typical ride involves lots of slow on the brakes downhill it might be a good thing. Generally though the next smaller rotor size on the rear makes sense. I did have a VP Free a while back and the rear brake on it would fade from overheating. Juicy 7's. Needed a good bleed more than anything but the larger rotor helped too.