Bad brakes

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PJ520
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Bad brakes

Postby PJ520 » 24 Jul 2017, 9:01pm

My Specialized Roubaix has the brakes it came with. The levers are Shimano 105 brifters. The calipers don't have a name on them, I presume they are bottom of the line Shimano, and they are not very good e.g. I couldn't send myself over the bars even if I wanted to. Thanks to a stroke some years ago and visits from Arthur my front brake grip isn't as powerful as it might be and I would like something more effective. Is replacing the no-name jobs with genuine 105 brakes likely to make much difference?
You only live once, which is enough if you do it right. - Mae West

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Si
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Re: Bad brakes

Postby Si » 24 Jul 2017, 9:08pm

I'd be inclined to try just changing the brake blocks first....shimano ones arent always that good in my experience. Also worth making sure the cables are nice and clean and free running.

PJ520
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Re: Bad brakes

Postby PJ520 » 24 Jul 2017, 9:18pm

I should have said that I tossed the Shimano "rim grinder" pads it came with and now use KoolStop orange which helps a bit. Recently I cleaned the rims with alcohol and sanded the pads down to virgin material but the brake is till not very good. I would like to be able to do one finger braking.(Single digit as someone once said) The rim is a Mavic CXP-22.

Good point about the cables I'll try new 'uns.
You only live once, which is enough if you do it right. - Mae West

Samuel D
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Re: Bad brakes

Postby Samuel D » 24 Jul 2017, 10:15pm

New, high-quality cables, lubricated (with Shimano Cable Grease, for example) and with optimised housing lengths and routing may make a big difference.

Are the pads accurately positioned so that their whole face contacts the rim’s braking surface? I ask because I see a lot of road bikes with the brake pads too low (or, worse, too high, risking tyre damage).

As for the callipers, are you sure they don’t have anything written on the back side of the arms? You may need to remove the brake to check.

Which Shimano 105 shifters do you have? You can peel back the hood to see the model number. What I’m getting at with these questions is that the brake lever and calliper may not be perfectly matched for cable pull.

New 105 callipers would likely be better (with Ultegra and even Dura-Ace better still due to the use of ball bearings to reduce pivot friction), but you’d need to get the right ones (matching the cable pull of your STI brake levers).

Brucey
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Re: Bad brakes

Postby Brucey » 24 Jul 2017, 11:17pm

CXP22 rims came in several flavours, including one with a large centrally positioned wear indicator groove. Braking is affected by this groove; a corresponding ridge usually forms on the brake blocks and should the brake arms flex at all, the braking efficiency immediately becomes worse than normal.

You can test if this is happening if you file any ridge off the brake block and then compare the braking performance before and after.

cheers
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old_windbag
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Re: Bad brakes

Postby old_windbag » 24 Jul 2017, 11:29pm

I imagine the brake release lever is in the correct position following adjustments? Yes obvious but I've seen people riding with them open and still have braking just very poor. I prefer campy in that respect having the push button on the lever.

Didn't offer this thought to be insulting.

tim_f
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Re: Bad brakes

Postby tim_f » 25 Jul 2017, 12:39pm

The calipers don't have a name on them, I presume they are bottom of the line Shimano,


Often they will save money by not fitting Shimano brakes. So if you can not see a model code on the calipers it is likely that they are not Shimano.

for example this 2015 model https://www.evanscycles.com/specialized-roubaix-sl4-sport-2015-road-bike-EV212308 has 'AX' brakes.

If replacing best to make sure you get the brakes from a 105 generation that matches the leavers.

I recall that when 105 went 11 speed they changed how the brake leveraged works.

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foxyrider
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Re: Bad brakes

Postby foxyrider » 25 Jul 2017, 9:05pm

Just buy a set of Campagdual pivots and you'll be wearing a face guide so save your gnashers from all the face plants! Almost any level will be an upgrade from Shimano.

My one Shimano braked machine has braking barely up to my discs which in turn are some where below the performance of my old Galli SP's from the 70's!
Convention? what's that then?
Airnimal Chameleon touring, Orbit Pro hack, Orbit Photon audax, Focus Mares AX tour, Peugeot Carbon sportive, Owen Blower vintage race - all running Tulio's finest!

flatout
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Re: Bad brakes

Postby flatout » 25 Jul 2017, 9:29pm

Agree with tim_f. A lot of bikes are built to a price point by compromising on components like brakes. The OEMs on my 2011 Cannondale Synapse lasted 18 months. The replacement Shimano brakes have so far done nearly 5 years without issue. I use Swissstop black pads.

gregoryoftours
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Re: Bad brakes

Postby gregoryoftours » 25 Jul 2017, 10:00pm

In case you weren't already going to, fit new cable outers, not just inners. Can be a large loss of power from outers that look fine on the outside but have worn lining. Also can try reducing reach in the levers with correct shims for the model or adjustment screws. Can apply more power with less reach as long as you make sure the levers aren't too close to bottoming out against the bar under heavy braking.

mattsccm
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Re: Bad brakes

Postby mattsccm » 26 Jul 2017, 8:23am

Can't comment from experience but many reviews refer to cost saving by manufacturers who fit non group set or non Shimano brake calliper. The latter is more likely.
The comments often suggest that this has led to a less than effective brake. May be an element of snobbishness or the desire to see a full group set but it may be true. Might I suggest trying a bike with full Shimano brakes.
Of course all of the other posts also apply.

Brucey
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Re: Bad brakes

Postby Brucey » 26 Jul 2017, 7:15pm

PJ520 wrote:... I would like something more effective. Is replacing the no-name jobs with genuine 105 brakes likely to make much difference?


There are a few issues ;

1) Shimano have changed their brake actuation ratio in recent years; as others have commented, a 'Matching caliper' (ie BR-5800 to go with ST-5800 etc) is probably a good idea. { IIRC Campag DPs won't work at all well with the most recent Shimano STIs BTW]

2) The actual brake performance will vary with the set reach of the brake; the same brake caliper fitted to different frames can vary by about 20% in MA depending on whether the brake blocks are in the top or bottom of the slots. Some of the most recent shimano brake designs have a moving caliper (that is slotted where it fits the frame) and these give more consistent performance (albeit with limited clearance over the tyre).

3) Shimano (in their wisdom) do not offer a deep drop caliper that perfectly matches their current STIs. Basically if your brake drop is over a certain amount (which is about 49mm IIRC) then the only brake calipers that shimano offer are the BR-R650 or the BR-R450 models. However these offer reduced braking power with the current STIs because they were really designed for the previous generation of STIs. Thus it may not just be cost-saving that causes manufacturers to use non-shimano calipers. Having said this, many of the non-shimano calipers that manufacturers fit do not have the correct actuation ratio either...

cheers
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PJ520
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Re: Bad brakes

Postby PJ520 » 27 Jul 2017, 3:56am

Thanks all for your suggestions. I've ordered 105 brakes and cable lube from Amazon. I'll let you know how it all works out.
You only live once, which is enough if you do it right. - Mae West

Brucey
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Re: Bad brakes

Postby Brucey » 27 Jul 2017, 7:43am

I hope they fit your frame; for some reason I have supposed that the drop on a Roubaix might be more than 49mm...?

cheers
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PJ520
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Location: Seattle WA USA

Re: Bad brakes

Postby PJ520 » 27 Jul 2017, 9:29am

Brucey wrote:I hope they fit your frame; for some reason I have supposed that the drop on a Roubaix might be more than 49mm...?

cheers
Let's hope. If they don't I'll return them and go to plan B whatever that is.
You only live once, which is enough if you do it right. - Mae West