Advice please regarding potential mechanical disc brake upgrade

Discussion in 'Bicycle Mechanics and Repairs' started by Howyadoinoutthere, 8 Mar 2018.

  1. I would like to improve the brakes on my wife's Cannondale CAADX 105 2016 cyclocross bike. It's only used for very light touring and short day rides on tow paths etc., but she isn't confident that the brakes can quickly stop the bike if need be. The bike came with Promax Render R, 160mm front and 140mm rear rotors. It is obvious from reviews that these are budget, poor performing brakes.

    I would like to upgrade the brakes and am thinking of the TRP Spyre as the most cost effective option but as someone who has never fiddled with disc brakes before am unsure about a few things before proceeding and would welcome any advice or encouragement.

    Do I just replace the calipers but retain the existing rotors? Or do I replace both the calipers and the rotors?
    The TRP Spyre caliper and rotor sets seem to be 160mm rotors so would I be correct in thinking that if I tried to replace the 140mm rotor and caliper with a 160mm set then it wouldn't fit?

    I'm keen to have a go at this - or do you think I should take it to my LBS?

    Any advice gratefully received.
  2. Tenacious Sloth

    Tenacious Sloth Über Member

    Huntingdon, UK
    I have the same bike, and have found that with a minor tweak the Pro Render brakes work very well.

    I upgraded the rear disc to a 160mm Rotor, for which I needed an additional bracket that moves the caliper a further 10mm out from the frame.

    The most important thing though is to bed the pads and Rotor in properly by repeatedly riding down a long hill with gradually increasing pressure on the lever, one brake at a time. Ensure you release the lever before coming to a standstill, unless you want to leave a blob of melted pad on the Rotor.

    Since doing this I can lock either wheel if I don’t distribute my weight correctly.

  3. Cycleops

    Cycleops Guru

    Accra, Ghana
    You can retain the existing rotors, just bolt the new calipers on, very simple.
    It seems with rotor size the post mounts can be shimmed out with spacers, that's how they work on my Specialized anyway (budget Tektros). I also aim to upgrade mine.
  4. vickster

    vickster Legendary Member

    I swapped BB5 for Spyres, Just the Calipers, very good move as the bike now stops without constant adjustment
  5. PpPete

    PpPete Guru

    Chandler's Ford
    TRP Spyre or HY/RD, or possibly the JuinTech cable operated hydraulics if you can find an adapter. Talk to for the latter.
  6. Pale Rider

    Pale Rider Guru

    The rear brake of a bicycle does next to nothing

    As a cost effective first step you could fit a cable actuated hydraulic to the front.

    There tends to be plenty of clearance around a bicycle's front brake so fitting the new brake should be simple.

    The bulkier hydraulic caliper can cause clearance problems on the back depending on where the existing brake is mounted.
  7. bikingdad90

    bikingdad90 Formerly chris harte

    You may need to fit a new brake cable if the existing cable is not long enough.
  8. I like Skol

    I like Skol I'm adamant I haven't got any PPI....

    Before you do anything it might be worth cleaning the rotors and replacing the pads with new ones. The current pads might be contaminated even if they look OK.

    See THIS for a little guidance.
  9. ColinJ

    ColinJ A big clot!

    I had a couple of very scary experiences with the inadequate Render R front brake on my CAADX. When I found myself descending a 20% hill and was not stopping despite having the front brake lever pulled hard onto the handlebar, enough was enough! :eek:

    I put a TRP HY/RD on the front of the CAADX and it did improve braking significantly. It still takes an awful lot of cable pull to lock the front wheel, but I can now do it.

    As pointed out by @Pale Rider above, the rear brake doesn't have much work to do so I left the Render R on. I can lock the wheel with it so it did not need replacing.
    Howyadoinoutthere likes this.
  10. ColinJ

    ColinJ A big clot!

    PS I found the Hy/Rd brake very easy to fit. If you fit one yourself be sure that you understand how to adjust it - it isn't done exactly the way that you would expect!

    You need to JUST take up the slack in the cable, no more than that. Make it so that the slightest movement of the brake lever starts to operate the brake.

    If you don't take up the slack then your brake lever will pull all the way to the bars without giving enough braking power.

    If you adjust too far and take up more than just the slack, you will defeat the self-adjust of the brake which compensates for brake pad wear.

    There is a little knurled screw which you can screw in on the side of the caliper to check that you have not over-adjusted the brake. If the screw can be screwed in, all is well. UNSCREW IT AGAIN AFTERWARDS! :okay:
  11. amasidlover

    amasidlover Veteran

    Another one here who switched from Promax Render Rs to Hy/Rd - the transition from a little braking force to lots is very smooth (albeit the lever throw is now longer) and locking the wheel (should you want to!) takes a lot less force on the brake lever.

    Dead easy to fit - although I found the return spring in the Hy/Rds nowhere near as strong (possibly explaining less force to apply the brake...) - which mean I ended up replacing my rear brake cable with Jagwire Road Pro XLs to get a 'clean' return every time.

    Although if I was doing the change now I'd be tempted to go full hydraulic now there are more choices of Shimano Hydraulic STI brifters.
  12. ColinJ

    ColinJ A big clot!

    The brake cables on my used CAADX had already been upgraded to Jagwires by its previous owner.
  13. Siclo

    Siclo Über Member

    Hy-Rd's are quite particular about which levers they like, for optimum results it needs to be a pretty new shimano. I can't remember when and how many times shimano changed the pull ratio. I do know 5600 (and equivalent) doesn't work at all well, 5800 (all latest 11 speed) is brilliant. Can't recall if 5700 works or not, although it is a different pull ratio to 5600. I think the latest tiagra is 100% compatible too, but don't quote me on that.

    There was a crazy situation where you couldn't buy a TRP lever that operated a TRP Hy-Rd correctly, but I think they've fixed that now.
    ColinJ likes this.
  14. byegad

    byegad Guru

    NE England
    I'd swap BB5s for a pin on a string!
    BB7s on the other hand rock.
  15. Elybazza61

    Elybazza61 Veteran

    TBH I would go the whole hog for full hydraulics rather than the HyRds although it will be more of a faff to fit(might need bleeding if the hoses have to be cut*), but you can pick up 105 spec hydraulics* for a good price now from someone like Merlin (cheaper than some trade prices:wacko:) .

    *These could be 'build kits" in plain packaging which will have 'easy-fit" connections but they may need shortening depending on the bike.
  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.
    Dismiss Notice