New to discs. What am I doing wrong?

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don1
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New to discs. What am I doing wrong?

Postby don1 » 13 Jul 2015, 2:48pm

Hi. I have a 2015 Croix de Fer with TRP hy/rd cable actuated disc brakes.

I've never had a disc brake bike before so it's likely the performance of the brake is down to my ineptitude of setting up/maintaining them.

It's meant to be an excellent brake, so I don't think it's a quality thing - I'm sure it's down to me.

Are there some general idiot guides about regarding setting up and maintaining disc brake systems ?

I clean with MucOff disc brake cleaner, and also experimented with Isopropylalcohol but not sure which is best.

Any general advice for bedding in brakes would also be appreciated.

Thanks in advance.

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[XAP]Bob
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Re: New to discs. What am I doing wrong?

Postby [XAP]Bob » 13 Jul 2015, 3:11pm

They are meant to be excellent brakes.

Loosen the bolts, apply the brake lever (hard) to centre the caliber then do the bolts up (still holding the brake lever, a toestrap might be good)

Ensure that the brakes don't bottom out (I.e. That you can't get the lever to touch the bars)
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Brucey
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Re: New to discs. What am I doing wrong?

Postby Brucey » 13 Jul 2015, 3:26pm

if the pads are contaminated with oil (or have been, ever) then no amount of cleaning will fix it; you need new pads.

If this is the problem, the brake might work OK the very first time it is used (for one stop perhaps) after the pads and discs are cleaned, but then immediately turn bad again.

cheers
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gerrymcm
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Re: New to discs. What am I doing wrong?

Postby gerrymcm » 13 Jul 2015, 4:08pm

I guess it's possible your pads are glazed.
I found I did this to my pads when I first went over to discs. Google the procedure bedding in your brakes but it's essentially repeated hard stops to wear away the glazed surface and get back to fresh pad.
good luck

freeflow
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Re: New to discs. What am I doing wrong?

Postby freeflow » 13 Jul 2015, 5:35pm

Are you having any specific problems?

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NATURAL ANKLING
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Re: New to discs. What am I doing wrong?

Postby NATURAL ANKLING » 13 Jul 2015, 5:52pm

Hi,
Pull the brake a take a Picture of the calliper arm and post it.
If the calliper brake arm makes more than 90 degrees with the exposed cable (from outer cable to cable clamp) with brake on then you may have to adjust the fixed brake pad.

I am finding with disc brakes that they need adjusting every 80 - 100 miles or so on off road.
Definitely more finesse needed to adjust than motor bikes cable / hydraulic.
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freeflow
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Re: New to discs. What am I doing wrong?

Postby freeflow » 13 Jul 2015, 6:37pm

Hi,
Pull the brake a take a Picture of the calliper arm and post it.
If the calliper brake arm makes more than 90 degrees with the exposed cable (from outer cable to cable clamp) with brake on then you may have to adjust the fixed brake pad.


There are no fixed pads on TRP HY/RD disc brakes. As the OP hasn't indicated what problems, if any, they are facing, its difficult to answer the question.

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NATURAL ANKLING
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Re: New to discs. What am I doing wrong?

Postby NATURAL ANKLING » 13 Jul 2015, 10:45pm

Hi,
I admit in being a bit naïve in modern disc brakes on cycles.
Dual action, well that eliminates the maintenance problem that I have but my bike was just £20 so fitting £60 brakes is unlikely unless I get lucky :)
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foxyrider
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Re: New to discs. What am I doing wrong?

Postby foxyrider » 14 Jul 2015, 8:41am

Been using the TRP's almost a year now and performance is well if not great, not bad. I do find that if the cable movement is set as the book braking is not brilliant so I keep that trimmed. Also as the pads wear - and i've seen this on other road hydraulic systems too, there may be a 'pulsing' when you brake. Not entirely sure what causes it but resetting the brake pull and or replacing the pads - organic are better than sintered, normally sorts it.
Convention? what's that then?
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NATURAL ANKLING
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Re: New to discs. What am I doing wrong?

Postby NATURAL ANKLING » 14 Jul 2015, 10:32am

Hi,
From my very limited knowledge of cycle disc brakes, you sum up does not sound good.

Much worse than my junk cable mechanical disc brakes, which are single activating.

Mine work as well as 110 MM V brakes and they are hot for sure.
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niggle
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Re: New to discs. What am I doing wrong?

Postby niggle » 14 Jul 2015, 1:37pm

The Tektro Io mechanical disc brake on my commuter, acquired for free from an MTB intercepted on its way into the recycling centre metals bin, was reasonable brake to start with, once set up properly, but when I recently replaced the pads with 'semi-metal' ones it was transformed into a powerful beast, though a bit noisier at times.

pioneer
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Re: New to discs. What am I doing wrong?

Postby pioneer » 14 Jul 2015, 2:15pm

For once, I disagree with Brucey. I contaminated my pads by accident with over zealous use of spray grease on the hub. Some found it's way onto the pads. They squealed like hell and caused juddering at the fork. But after taking them out and a good clean with some glass paper to remove the muck, the pads were good as new again. Also found (again, by accident), that white spirit is not the stuff to use to clean the discs. Apparently it leaves a very thin, oily residue which again, bungs up the pads. The proper disc cleaning fluid is the stuff. It would be, it's much more expensive! And though in heavy rain, you don't get that horrible noise of rim brake pads literally wearing away the rim every time the brake is applied, you may still get some serious squealing from the disc and pad interface time to time. I like to think of it as an audible warning device!
I think with any new technology on a bike, there is a little settling in period of time which needs to elapse for the rider to learn about, and adapt to new stuff and ways of doing things. I wasn't at first overly impressed with the disc brakes on my Genesis, but now after almost two years, I think they are the canines whot-sits.

Brucey
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Re: New to discs. What am I doing wrong?

Postby Brucey » 14 Jul 2015, 2:27pm

in fairness grease varies and in any event does not penetrate pads like oil does. Furthermore pads vary too. I'd fancy my chances of cleaning a set of (say) sintered pads that were briefly contaminated with a spray grease, whereas organic pads contaminated with a light oil are scrap for sure. IIRC the TRPs are supplied with organic pads.

The OP hasn't said what the issue is but given that pads are consumables anyway, it doesn't hurt to clean and reset everything and to fit new ones. Often simply doing all this reveals other issues. If the pads are actually OK then they can be kept as spares, so nothing is really lost this way.

BTW a cheap and efficient solvent for cleaning discs etc is cigarette lighter fluid. Use a little on clean tissues to wipe suspect parts, and examine the residue on the tissues. You can buy the fluid in the pound shop. It leaves no residue of any kind, and unlike some other solvents (eg acetone, cellulose thinners etc), it does not attack paintwork and plastics.

cheers
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Dave W
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Re: New to discs. What am I doing wrong?

Postby Dave W » 14 Jul 2015, 5:04pm

Have a look on Youtube - plenty of info about on how to set up TRP disc brakes.

Mattyfez
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Re: New to discs. What am I doing wrong?

Postby Mattyfez » 14 Jul 2015, 8:08pm

Not much to add, but some further considerations..

Not sure what cable actuated hydraulic is, some kind of hybrid system I guess, on mountain bikes they tend to be either one or the other.

Mechanical disc brakes do not self adjust with pad wear, so will need to be moved closer to the discs as they wear.
They can also be a faf to set up correctly, but work great when well adjusted, plenty of videos on YouTube to give you an idea, but eventually you'll get a feel for it.

Also I've heard that quite often the genuine pads are removed and cheaper ones supplied.

Just things to bear in mind, not saying that is the case.
There are also different pad materials available, the main ones being organic and sintered (semi metallic) which have slightly different characteristics, plusses and minuses.

Bedding in the pads is very simmilar to bedding in car brakes as they are simmilar.. Most times it just happens naturally, but there is a process if in doubt, drag the brakes slightly for five or ten minutes to warm them up a little, (in cars this is to prevent thermal shock to the rotors, probably not a massive issue on a bike but I thought I'd mention it) and then get some speed up, and anchor on but don't come to a complete stop, just coast. Build speed back up again and repeat five or ten times.
You want to be braking as hard as possible without locking the wheels up.

On a bike it might be easier /safer to bed front and rear separately.