peggysue Posted May 12, 2011 Report Share Posted May 12, 2011 Bought a new a2z 203mm front rotor off tarty , fitted Wednesday and went for first ride tonight . Braking was getting more powerful as I dragged it on and off towards town .... However decided to do my normal gap to front about 5 foot , landed fine , brake slipped abit (not fully bedded in) , only to find a nice big bend in the rotor . The wheel would hardly turn as at least 1/5th of the disc was bent to hell ! Is this a common problem ? I can only put it down to either 1.... I weight 18 stone ? 2..... A faulty disc ? Any help ? Thanks Quote Link to comment Share on other sites More sharing options...
Matthew_Gibson Posted May 12, 2011 Report Share Posted May 12, 2011 there may be contaminants on the disc. get the rotor nice and hot, and soak it with clean water. always worked for me..... Quote Link to comment Share on other sites More sharing options...
peggysue Posted May 12, 2011 Author Report Share Posted May 12, 2011 Contaminants on the disc can cause it to bend ?? Quote Link to comment Share on other sites More sharing options...
24martin Posted May 12, 2011 Report Share Posted May 12, 2011 Contaminants on the disc can cause it to bend ?? no i dont think so, was your caliper properly aligned / centralised with the disc?? and are all your bolts on the caliper and disc nice and snug? Quote Link to comment Share on other sites More sharing options...
Sam T Posted May 12, 2011 Report Share Posted May 12, 2011 Contaminants on the disc can cause it to bend ?? No, I think he misunderstood. Quote Link to comment Share on other sites More sharing options...
Matthew_Gibson Posted May 12, 2011 Report Share Posted May 12, 2011 yeh i was sorry. :$ but it helps if you do that too. what brake is it most likely not set up correct... Quote Link to comment Share on other sites More sharing options...
peggysue Posted May 12, 2011 Author Report Share Posted May 12, 2011 Avid bb7 and was set up perfect all nice and tight to , had a 185 disc on before with no problems at all .... Thought it might be the rotor design being to weak or something ? Or faulty ? Quote Link to comment Share on other sites More sharing options...
casualjoe Posted May 13, 2011 Report Share Posted May 13, 2011 Rotor on the wrong way round causes it to warp pretty quick. Quote Link to comment Share on other sites More sharing options...
peggysue Posted May 13, 2011 Author Report Share Posted May 13, 2011 Rotor was on right way too rang tarty and they thought it was weird too . Might not have been heat treated properly ! Will be sending it back to them Monday for them to have a look Quote Link to comment Share on other sites More sharing options...
giantwhore Posted May 23, 2011 Report Share Posted May 23, 2011 Had exactly the same problem with my bb7 when i was running a the same rotor. i think the main problem is that with a bb7, one pad is static and the other pad pushes the rotor against the static pad. Only problem with that is that if the rotor isnt very strong laterally then even in short space of time (1 ride for me) the rotor can bend. I bought a second one of the same rotor and had exactly the same problem. Anything heavy to the front wheel (gaps etc) and the rotor would just give up. It got to a point where i was having to bend the rotor straight at the end of every ride just so i could ride back to the car without it rubbing enough to slow me down. I've swapped to the standard avid rotor and had no problems at all. Chris Quote Link to comment Share on other sites More sharing options...
Luke Rainbird Posted May 23, 2011 Report Share Posted May 23, 2011 If you're running a brake where one pad is static you should always try to set it up as close to that pad as possible to minimise the rotor deflection. A steel rotor will have enough elasticity to be pushed across 1mm or so without being permanently bent! Quote Link to comment Share on other sites More sharing options...
Greetings Posted May 23, 2011 Report Share Posted May 23, 2011 Apart from what's already been said, the front wheel could have not been tightened properly to the fork. Quote Link to comment Share on other sites More sharing options...
peggysue Posted May 31, 2011 Author Report Share Posted May 31, 2011 Just thought I would update this .... I set the rotor back to tarty and they sent it off to the manufacturer who covered it under warranty . Only possible explanation off tarty was possible heat treatment was not done properly , but it's a guess . New rotor arrived and although I've ridden for 14 years and worked as a bike mechanic for a few years , tarty just advised me to bed it in slower this time . My setup is perfect . As I've read the replies to this thread and everything I've done is spot on . Once again my setup was great , put the new rotor on and off I went . I rode last week , with no front wheel moves at all , and Saturday with no front wheel gaps , just taking tartys advice . Went out tonight for a ride , the disc has bedded in nicely now and decide to try my first gap to front , and guess what ? It god dam bent again upon landing .... Really pissed me off now . Nothing is loose , and it's setup near perfect . This disc rotor is either a shite design or it can't handle my weight ! I'll have to ring tarty tomorrow and see what they can do . Quote Link to comment Share on other sites More sharing options...
craigjames Posted May 31, 2011 Report Share Posted May 31, 2011 It's not something daft like the forks/wheel twisting with the extra amount of force the bigger rotor is applying? Seems a little weird! Quote Link to comment Share on other sites More sharing options...
peggysue Posted May 31, 2011 Author Report Share Posted May 31, 2011 Not sure mate , it's just more of a big twist in the rotor rather than a in or out bend that can be bent back easily . It's nearly impossible to get a twist out the rotor Quote Link to comment Share on other sites More sharing options...
ogre Posted May 31, 2011 Report Share Posted May 31, 2011 lol you beast... get a solid disc... Quote Link to comment Share on other sites More sharing options...
Martin Reynolds Posted May 31, 2011 Report Share Posted May 31, 2011 Posibally by heavy breaking? can cause the rotor to heat up/cool unevenly, causing the disc to warp Quote Link to comment Share on other sites More sharing options...
craigjames Posted May 31, 2011 Report Share Posted May 31, 2011 Posibally by heavy breaking? can cause the rotor to heat up/cool unevenly, causing the disc to warp But that wouldn't apply to a gap to front. Sudden braking doesn't induce that level of heat and not to a big enough part of the disc. Quote Link to comment Share on other sites More sharing options...
kevind Posted June 1, 2011 Report Share Posted June 1, 2011 Sorry I dont know the disc in question, but from what you say, in my thought process is it that the SUDDEN loading from the tyre gripping and the weight applied from the rider and bike is causing the rotor part to move in relation to the wheel mounting part of the disc. (ie the small arms of metal that connect the two and are usually smallish to save weight) This would cause the disc to warp as the rotational forces would have to go some where other than parallel with the mount and the braking surface. I am 17 stone and although I dont do much on my trials bike, I have a downhill rotor and a old Hope M4 caliper (its what I had lying around) It never moves but probably weighs more, but I weigh more anyway!! Quote Link to comment Share on other sites More sharing options...
peggysue Posted June 1, 2011 Author Report Share Posted June 1, 2011 I think I'm putting this down to a flimsy design that's not been tested properly . It maybe alright with a 10 stone kid but as I'm 18 stone the 203mm rotor is too flexy or me . No other reason . I ran a 185 disc with no problems at all but as the trialtech forks are a +20 mount I have to use the 203 rotor now . Looking at the a2z design the arms that connect the centre of the disc to the braking surface are long and thin . I think thatsthe problem . The 203 version should be beefier . I can imagine the smaller versions of this disc being stronger and less flexy . The hope saw rotor looks strong as it's got such a stiff looking design . Quote Link to comment Share on other sites More sharing options...
LukasMcNeal Posted June 1, 2011 Report Share Posted June 1, 2011 You could still run a 180 just use a 160 caliper Quote Link to comment Share on other sites More sharing options...
peggysue Posted June 1, 2011 Author Report Share Posted June 1, 2011 Well I've just put an order in for a hope saw rotor in 183 mm size . Would be gutting if I tried a hope saw 203 and that bent If I flip the caliper mount upside down I can run a 185 disc so I'll do that with the 183 and hopefully the beefy design and stiffer size should be good and strong ! If it brakes again I'll be going back to vee's lol Quote Link to comment Share on other sites More sharing options...
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