Struggling with TRP integrated brakes setup

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OhPinchy
Posts: 80
Joined: Wed Feb 27, 2013 5:38 pm

by OhPinchy

I have a Dolan Scala TT bike and after replacing the handlebars am having trouble reconfiguring the integrated TRP brakes. I kinda got lucky and managed to get the front brakes working by fluke despite not really knowing what the right method is. But I'm struggling with the back brakes. And I've also fitted my Gigantex 50mm carbon wheels into it - they're running Veloflex Arenberg tubs which are 25mm if I recall correctly, and I think the width of the wheels is thicker than usual, 23mm or so.

Not sure how to post a full resolution photo, so I've uploaded a file to http://1drv.ms/1CLc9IQ

At the arrow below point C in the photo, you can see that the brake fitting is rubbing off the tyre. Would using a Dremel to remove the bit sticking out from the brake fitting solve this, or is it ill advised and I have to accept that using the bike with these wheels won't work? Major bummer if so as I have a RAL Tech carbon wheel cover on those wheels specifically for time-trials on that bike, so will be a bit of a gutshot if not possible.

I couldn't find any info online on how to configure the brakes so just played around with it and undid bolt A using a special star screwdriver fitting, pushed in the brake pads, and then tightened it - gap is way too big between pads and wheel and I'm guessing there's a smarter way to do it? Does it involve adjust the fittings at point B at all? There's also screws on the side of the brakes that I can't figure out what they're for (they're separate to the bolts that hold the pads in). Any and all advice to get this thing figured out is much appreciated as I need to get out on this bike this week to have my position full dialled in for a TT event at the end of the month.

natefontaine
Posts: 249
Joined: Wed Mar 31, 2010 3:37 am

by natefontaine

Be sure that when you installed the arms that the adjustment spring is correctly positioned and under tension. Alignment is set by the tensioner screws, loosen the NDS tighten the DS. To gain some pad clearance you can remove the spacers between the pad holder and the arms. Then adjust the cable length. Once you have it all dialed down, cut the cable and feed it back through the hole behind the pad holder for a nice clean look. I'll try to get a pic of mine soon for you.

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OhPinchy
Posts: 80
Joined: Wed Feb 27, 2013 5:38 pm

by OhPinchy

Thanks natefontaine. I do believe the adjustment springs on the arms are correctly positioned and under tension, they do spring back after I squeeze the pads in and release.

Whereabouts are the tensioner screws, and what does NDS and DS stand for? I did muck about with the bolt at point B in the photo a while back and think it undid the tension in the adjustment spring, so a mechanic fixed that at the time and I haven't gone near it since. Are the tensioner screws on the side of the arms or are they visible in the view in the photo?

Any thoughts on whether 25mm tyres can fit with this setup and potentially filing off the bit of metal sticking into the wheel, or will a cleaner install prevent the need to do that? Thanks!

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dwaharvey
Posts: 470
Joined: Thu Oct 26, 2006 8:54 pm
Location: USA

by dwaharvey

NDS = NON Drive side
DS = you guessed it

With the arms properly centered on the wheel I suspect that the part at "point C" won't be above the high point of the tire any longer and therefore won't cause you an issue. But if it does, I wouldn't be overly worried about modifying it a little bit if that was all it took to work.

To center the arms one the wheel, as nate said, you need to adjust the tensioning screws. There is one on each side of the arm, not visible in your photo because they are on the side of the arm facing outwards. If memory serves, they're 2.5mm or 3mm allen bolts. If you tighten the bolt, then you increase the tension on the spring on that arm, and consequently move the arm away from the wheel. Since you want to move the arms towards the DS, you need to either: 1) loosen the bolt on the NDS, or 2) tighten the one on the DS, or 3) do both 1 & 2.

OhPinchy
Posts: 80
Joined: Wed Feb 27, 2013 5:38 pm

by OhPinchy

Nice one dwaharvey, that makes it quite clear. I'll give that a go this evening. Would it be best to loosen the cable bolt and restart (what steps should I follow if so)? Or leave it as it is and adjust the tensioning screws on the side of the arms?

Marin
Posts: 4035
Joined: Wed Jan 22, 2014 11:48 am
Location: Vienna Austria

by Marin

With V brakes, you can often swap spacers on the brake pads from the inside to the outside to change the brake arm angle when the brakes are engaged to compensate for rim width vatiation. This could already move the retainer off to the side.

You should be able to dremel of a mm or two as well.

BTW your cable is torn at the clamp it seems.

natefontaine
Posts: 249
Joined: Wed Mar 31, 2010 3:37 am

by natefontaine

Unfortunately, you need the brake cable under tension to set up the alignment. An in line cable adjuster helps, but can be difficult to install for the rear. Also, mine came with a liner that fits in the elbow, it extends outside of the elbow possibly reducing friction. I noticed yours doesn't have that liner.
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My camera sucks, but you get the idea

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OhPinchy
Posts: 80
Joined: Wed Feb 27, 2013 5:38 pm

by OhPinchy

Thanks for the pic. I wonder if that sleeve was initially present on my brake (it's there on the front brake) but was a casualty of the last round of adjustments that were made by the mechanic to the brakes to fix the adjustments I had made to the tensioner bolts.

I used a cable puller tool to put some pressure on and then screwed the cable-holder bolt closed. When the bolt tightened, the brake arm on the far side jumped inwards. Wonder could the absence of the sleeve be causing that?

Hope I don't have to get a new brake. Will play around with the tension adjustment screws on the side when I get a chance tonight, after replacing the brake cable given it is frayed.

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