rotor questions

[bitt3n]

I need an adapter to go from a 160mm to a 140mm rotor on this fork:



I'm having trouble figuring out where to get the correct adapter, as when I search for it all the adapters I've seen convert 140mm forks to 160mm. I suppose another option would be just to buy a 160mm rotor but I'm not sure it's worth it since I've already got a set of functional 140s.

I'm wondering if someone can point me to the right part number, and also I'm curious whether it would be worth just getting a 160mm rotor. Would the difference likely be noticeable?

[Mark McM]

Looking at the geometry, there doesn't appear to be enough clearance between the caliper and the fork to move the caliper inward enough to align with a 140 mm rotor (adapters can space a caliper outward, but they really can't space the caliper inward).

I think your simplest and best option is just replace the rotors. You'll get better performance with the larger rotors, anyway.

[Fatty]

Originally Posted by Mark McM

Looking at the geometry, there doesn't appear to be enough clearance between the caliper and the fork to move the caliper inward enough to align with a 140 mm rotor (adapters can space a caliper outward, but they really can't space the caliper inward).

I think your simplest and best option is just replace the rotors. You'll get better performance with the larger rotors, anyway.

That is what I would do. Keep the 140 for a spare for out back.

[ColonelJLloyd]

Your post is a little vague or I haven't had enough coffee.

Is that your photo?

The photo shows a 140mm rotor. If that's the fork you are using and your calipers are post mount then you do not need any adapter. The caliper mounts directly to the fork.

But, yes, a 160mm rotor in the front will offer noticeably better modulation and overall power. If you do not already have the adapter to use a 160mm rotor with that fork, it is this (or similar from other maker).

[bitt3n]

Originally Posted by Mark McM

Looking at the geometry, there doesn't appear to be enough clearance between the caliper and the fork to move the caliper inward enough to align with a 140 mm rotor (adapters can space a caliper outward, but they really can't space the caliper inward).

I think your simplest and best option is just replace the rotors. You'll get better performance with the larger rotors, anyway.

Thanks, I was afraid that might be the answer.

Originally Posted by ColonelJLloyd

Your post is a little vague or I haven't had enough coffee.

Is that your photo?

The photo shows a 140mm rotor. If that's the fork you are using and your calipers are post mount then you do not need any adapter. The caliper mounts directly to the fork.

To clarify, the way the caliper is mounted accommodates a 160mm rotor, but I have a 140mm rotor, so I either I need to swap out the 140 for 160 or find some kind of an adapter that allows me to use to the smaller rotor. However it appears such a thing does not exist. (That is my picture.)

[hollowgram5]

I can only assume that you have an older (but still great) QR Enve CX fork, as the RD fork was compatible with 140 rotors.

I'd just stick with 160 up front. I won't run anything less than 160 up front for myself. Just doesn't make any sense to try to go that small up front, but that is just my opinion.

There is no adapter to go smaller on a fork like that. They just don't exist, much like there are no adapters to take a flat mount caliper and get it to work on an ISO or Post mount frame/fork mounting point. ( Campag hydro )

[ColonelJLloyd]

Originally Posted by bitt3n

To clarify, the way the caliper is mounted accommodates a 160mm rotor, but I have a 140mm rotor, so I either I need to swap out the 140 for 160 or find some kind of an adapter that allows me to use to the smaller rotor. However it appears such a thing does not exist. (That is my picture.)

Then your fork is 160mm minimum. This is standard on a lot of forks for good reason.

[John H.]

Not sure why people feel the need for 140mm rotors.
Other than saving a few grams on the scale (of coffee shop test)- the 140mm rotor does not work as well.
It will heat up more quickly, causing your fluid to heat up too- All of this can cause the pads to drag on the rotor more than it normally would.
Stick to 160mm front and rear for best function.

1st year disc bikes were out- my local shop sold a bunch of Roubaix disc bikes that came with 140mm rotors- Lots of issues with people making their fluid boil on descents.

[bitt3n]

Originally Posted by John H.

Not sure why people feel the need for 140mm rotors.
Other than saving a few grams on the scale (of coffee shop test)- the 140mm rotor does not work as well.
It will heat up more quickly, causing your fluid to heat up too- All of this can cause the pads to drag on the rotor more than it normally would.
Stick to 160mm front and rear for best function.

1st year disc bikes were out- my local shop sold a bunch of Roubaix disc bikes that came with 140mm rotors- Lots of issues with people making their fluid boil on descents.

interesting. I took this group off a Cannondale Black Inc Disc 2015, not realizing rotors are typically 160mm

[bitt3n]

Ok I guess I'll buy new rotors..

I'm going to need a rear adapter also. Just to confirm, given that my frame has an IS mount, is this the adapter I'll need to use a 160mm rotor with my post-mount caliper used as a rear brake?

[hollowgram5]

That appears correct yes. What frameset are you putting this on?

[bitt3n]

Originally Posted by hollowgram5

That appears correct yes. What frameset are you putting this on?

A Seven Airheart, which is the Evergreen model with S&S couplers

[hollowgram5]

Sweet! That will be an awesome build!