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Force HydroR Discs Caliper Spacer Confusion

5K views 12 replies 7 participants last post by  cxwrench 
#1 ·
SO I swapped out an old set of TRP Spyres on my 2015 Giant TCX for a new set of Sram Force Hydro discs.

I'm super happy to have them on, they feel great at the lever, but I admit I haven't gotten to ride them yet.

One thing that keeps throwing me off though is that the front caliper spacing (in particular) looks...... weird. It just looks somehow too far out to me, and I noticed that when I look at down through the caliper from above there is quite a bit of space between the top of the disc and the top of the 'cavity' within the caliper.....moreso than I'm used to seeing on other brakes. It almost looks like the pads are only contacting 1/2 of the braking surface of the 160 disc.

I looked at the spacers my mechanic used, a 17.5mm and a 12.5mm, and see that this is the appropriate setup for a CPS Caliper and a 160mm disc on 140mm post mounts. ...it appears that IF my calipers were 'standard' calipers I would only need a 12.5 and a 7.5mm spacer. I just don't know how to tell whether my caliper is CPS or standard to tell whether the mechanic may have made a mistake or not. I looked at the picture on the sram caliper installation .pdf, but the differences between the two caliper types seem too minute for my eyes.

Anyone know how I can check my caliper type and ensure that my spacer arrangement is correct? Bicycle wheel rim Mode of transport Spoke Rim Bicycle accessory
Mode of transport Bicycle part Bicycle accessory Bicycle tire Bicycle frame
Bicycle tire Bicycle wheel rim Mode of transport Spoke Bicycle part
Bicycle wheel rim Bicycle tire Bicycle part Bicycle accessory Bicycle frame
 
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#2 · (Edited)
The piston appears to be in the right place for those CenterLine rotors.

Any closer and it appears the rotor would hit the caliper body.

I have never been a fan of the CPS Avid set up. I believe it was a major contributing factor to the dredded "Turkey gobble" many Avid disk brakes users have been plaqued with for yrs.

Here's a link to SRAMs fun about CPS, Std and Smurf mount calipers

http://cdn.sram.com/cdn/farfuture/u...000-000_rev_b_disc_brake_caliper_mounting.pdf

Here's a snippy from it.
Text Line Font Parallel Diagram
 
#3 ·
Just wanted to top this up... Brought the bike back to my mechanic and he now agrees with me that something is amiss with the caliper spacing... the pads definitely only contact about 1/2 of the actual braking surface of the caliper. He also agrees that there is clearly more space in the caliper body for it to be closer to the rotor. The interesting thing is that he followed the guidelines of the chart you've copied above, which is the same chart that I reference in my original post. If the caliper is a CPS caliper then I think it *should* be right....but I'm really starting to wonder if its possibly a 'standard' caliper and if I just need to remove the CPS spacers that came with it.... TBD...I'm away on vacation now, and when my mechanic tried to call Sram for guidance he ended up waiting on hold for a 1/2 hour until he got disconnected...

I'll let you know how it shakes out!
 
#4 ·
Looking at the photo of your caliper and the illustration I'd say it's obvious you have a non-CPS caliper. Look at the mount compared to the bleed screw. It looks like you have a fork made for 140mm rotors but are running a 160. So, get the adapter that goes from 140 post mount to 160 and mount the caliper with no washers. The adapter you have only works with CPS washers. If you had a 160 rotor with your Spyres use that adapter. I've seen some weird caliper/rotor/adapter combos and the best advice is to let common sense and what you see dictate the setup, not confusing and sometimes contradictory instructions. If the top of the rotor touches the caliper it's too close. If not all the pad is hitting the braking surface it's too far.
 
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