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What can I do to improve my disc brake performance?

lozbrown85lozbrown85 Posts: 3
edited December 2010 in MTB workshop & tech
I've had my bike for about 2 months and I'm still having issues with the front brakes.

Its a Lapierre Spicy with Formula RX1 brakes, the back one seems ok and locks up under heavy braking but the front does not seem very powereful, pulling the front bake hard at speed results in gently gliding to a halt when i would exspect it to result in launching me OTB or at least a stopie. The behavour is quite consistant, it does not get worse or better, its just allways a bit poor. I originally put this down to bedding in but it does not seem to be improveing

I've tried:
- Cleaning the rotors with Isopropyl Alcohol
- Give te pad surface a light sand to remove any shiny bits

Do i need to cash out on one of these and get messy with bleeding them or is there anything else I can try first?
http://cgi.ebay.co.uk/Epic-Formula-R1-R ... 2a0c4772ac

I'm also having dificulty getting them to stop rubbing, I've tried unding the retaining bolts, holding the lever and re-tightening them but the still rub very slightly, is there anything else I should try?
Please help as its ruining my enjoyment of my new purchase, I ended up in a snow filled ditch last weekend because I couldn't stop fast enough, which was cold to say the least.

Posts

  • I'd swap the pads front to back and see if the problem moves with them.
    Northwind wrote: It's like I covered it in superglue and rode it through ebay.
  • peter413peter413 Posts: 5,120
    Don't be lazy with aligning your caliper, look at the pads with your eyes and see why they are rubbing, unscrew one bolt and push the caliper so that the rotor is in the centre then tighten the bolt up. Repeat for the other bolt. This is after you have partially aligned the caliper with the method you described
  • Do you have anything to compare the relative performance with? I'm just thinking you're expecting too much.

    If it's rubbing, a rule of thumb for the front is turn bike upside down, and spin wheel hard and if it comes to a stop in less than about 10 turns then there's something up, if not don't worry.
  • Cool thanks for all the tips, all usefull.

    My old bike has Hayes HFX 9s which apart from one issue with poping the bleed plug out were pretty excellent.
  • captainflycaptainfly Posts: 1,001
    Firstly swap pad from front to rear, just to chec. Then there is the softer pads on the front and a bigger rotor, but it is probably a riding thing, having too much weight at the front of the bike combined with stiffer front suspension. Try hanging you bum over the back wheel when braking downhill stylee :lol:
    -_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_
    Mongoose Teocali
    Giant STP0

    Why are MTB economics; spend twice as much as you intended, but only half as much as you wish you could afford? :roll:
  • jimexboxjimexbox Posts: 200
    peter413 wrote:
    Don't be lazy with aligning your caliper, look at the pads with your eyes and see why they are rubbing, unscrew one bolt and push the caliper so that the rotor is in the centre then tighten the bolt up. Repeat for the other bolt. This is after you have partially aligned the caliper with the method you described

    Good advice.

    I recently fitted a set of Formula The One, I spent ages aligning the callipers until I was happy. Once bedded in they are awesome, dangerous to the unwary. Pull too hard and you will imitate superman.
  • Do you have anything to compare the relative performance with? I'm just thinking you're expecting too much..
    This just isn't right. Any brakes, even really average ones should be fully capable of totally locking the wheel - and he has good ones. Back wheel - giant skid, front straight over the bars..... Unless there is something wrong.

    Does the brake lever feel solid when the brakes are applied? eg does the brake lever feel it has nowhere else to go? Or does it feel spongey like you can squeeze it harder? If so you may have air in the system and need to bleed.

    If not my guess is duff pads - maybe contaminated? this is where you can rule this out as suggested by swapping the pads from front to back.

    If none of this works, take back to the shop..... you have a 12month guarantee on the parts so use it. The brake aint right.
  • NorthwindNorthwind Posts: 14,675
    Do you have anything to compare the relative performance with? I'm just thinking you're expecting too much.

    Definately not, any brake should be able to beat what he's describing and RXs certainly can, they're pretty meaty.

    OP- pads first, then bleed. You'll need a bleed kit and new pads sooner or later so rather than letting it spoil your fun bite the bullet.
    Uncompromising extremist
  • nicklousenicklouse Posts: 50,675 Lives Here
    new bike then back to the shop for them to sort it.

    it is either poor set up or contamination.
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • cavegiantcavegiant Posts: 1,546
    I was going to say buy formula brakes...but you did..dammit.

    They are more fiddly to set up than normal brakes but worth the investment.
    Why would I care about 150g of bike weight, I just ate 400g of cookies while reading this?
  • mc11asmc11as Posts: 12
    i had similar problem with my front brakes, needed new pads as they were contaminated.
    blead the system to be on the safe side and gave the rotor a good clean, they are stopping me instantly now.
  • ali$tairali$tair Posts: 373
    Back to the shop where you got it from....let them sort it under warranty!
    Trek Fuel EX 8 (2010)
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