Another canti brake question, hopefully an easy one!

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gerrymcm
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Another canti brake question, hopefully an easy one!

Postby gerrymcm » 8 Jul 2016, 3:04pm

Hi folks,
I've got myself a nice Mercian frame (1989 year) and I'm starting to build it up and need some advice on canti brakes, I know it's been covered lots of times but this question should be simple!

The front forks studs/bosses are only 60mm apart and I wondered what the best canti brakes to put on it are?

I'm intending to use 8 speed STIs and after raiding the parts bin I have 4 sets of cantis to pick from.

Shimano BR-C510 brakes
br_c510.jpg


Shimano BR-R550's
br-r550.jpg
br-r550.jpg (8.04 KiB) Viewed 1402 times


Tektro CR720's
Teltro_720.jpg


Shimano CX50's
cx50.jpg


Which brakes will work the best?

Thanks
Gerry

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531colin
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Re: Another canti brake question, hopefully an easy one!

Postby 531colin » 8 Jul 2016, 5:33pm

See if you can set up the BRC510 as mid-profile (arms at 45 degrees, like the CX 50)
If you can set them up as mid-profile, they are your winner, because you can easily fit decent aftermarket pads.
CX 50 can be made to take aftermarket pads, but its hard work, and Shimano original pads are very abrasive.

gerrymcm
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Re: Another canti brake question, hopefully an easy one!

Postby gerrymcm » 8 Jul 2016, 8:29pm

Many thanks Colin, I appreciate your input.
I'll give that a go, I 'may' have made a mistake going for such wide rims at 24mm.

Thanks
Gerry

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531colin
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Re: Another canti brake question, hopefully an easy one!

Postby 531colin » 8 Jul 2016, 9:32pm

Those BRC510 look like they are designed as low-profile, so wide rims might help you persuade them to adopt mid-profile set up.

gerrymcm
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Re: Another canti brake question, hopefully an easy one!

Postby gerrymcm » 9 Jul 2016, 2:32pm

Hmm just had a thought, I have a spare pair forks, which are almost identical in design, same fork crown, same A2c and appear to be the same rake (with more mounts also :) ) so I'm considering putting these onto the frame as the studs are 78mm apart.

The rear studs are 70mm apart.

coling531 would that make a difference to you sugesting I use the BRC510's?

Thanks

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gaz
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Re: Another canti brake question, hopefully an easy one!

Postby gaz » 9 Jul 2016, 3:13pm

531colin wrote:... wide rims might help you persuade them to adopt mid-profile set up.

As demonstrated by Greybeard: viewtopic.php?f=5&t=70964&p=611806&#p611766
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531colin
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Re: Another canti brake question, hopefully an easy one!

Postby 531colin » 9 Jul 2016, 3:28pm

gerrymcm wrote:Hmm just had a thought, I have a spare pair forks, which are almost identical in design, same fork crown, same A2c and appear to be the same rake (with more mounts also :) ) so I'm considering putting these onto the frame as the studs are 78mm apart.

The rear studs are 70mm apart.

coling531 would that make a difference to you sugesting I use the BRC510's?

Thanks


80mm (ish) stud spacing gives you a choice of modern brakes, if you want to buy a modern brake (mini vee, CX70 ?....).....
.....but the BRC510s might set up OK as mid-profile on either pair of your forks....you won't really know until you bung them on....
The CR720s will be resolutely wide profile
The BRR550 I don't think will set up as mid profile, the pads won't adjust enough for angle apart from anything else?
CX50 are already mid-profile on 80mm studs, but won't accept decent pads without work. (and will probably need an adjustable straddle for best advantage.

MikeDee
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Re: Another canti brake question, hopefully an easy one!

Postby MikeDee » 9 Jul 2016, 3:30pm

The R550 is the best brake of all of them. They use ez to adjust pads. Stay away from the brakes that use unthreaded brake pad posts. They are a royal pain to adjust. Kool Stop also makes thinline pads, if you don't have enough clearance. Put the small spacer on the inside too. The Tektro's might be OK too, but in general, old fashioned wide profile brakes don't work as well.

gerrymcm
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Re: Another canti brake question, hopefully an easy one!

Postby gerrymcm » 9 Jul 2016, 3:40pm

Great thanks guys for the replies folks I appreciate your time.
The 80mm stud fork makes me think maybe mini Vs but as i have the cantis I might as well try them.
Cheers
Gerry

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531colin
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Re: Another canti brake question, hopefully an easy one!

Postby 531colin » 9 Jul 2016, 6:02pm

MikeDee wrote:The R550 is the best brake of all of them. They use ez to adjust pads. Stay away from the brakes that use unthreaded brake pad posts. They are a royal pain to adjust. Kool Stop also makes thinline pads, if you don't have enough clearance. Put the small spacer on the inside too. The Tektro's might be OK too, but in general, old fashioned wide profile brakes don't work as well.


BR550 is a low profile canti. The snag with all low profile cantis is the way the mechanical advantage alters with the straddle yoke position....
When the yoke is high, the MA is low, and when the yoke is low the MA is high......what we actually want is the other way round, when the yoke is low we could do with low MA, so the pads approach the rim quickly with little lever movement, and when the yoke is high(er) we want high MA so we stop.
(this also happens with mid-profile cantis, but the effect is nothing like as great)
The solution is to put the barrel adjuster in the straddle wire......

Image

Tektro do this on one low-profile canti, that I'm aware of.

The maths is all here......http://forum.cyclinguk.org/viewtopic.php?f=5&t=57410

Its true that low profile cantis have a maximum MA that is higher than mid-profile cantis, but they are harder to live with. You can start the day with excellent brakes, but a couple of hour's roughstuff or a wet hilly day ride can dramatically reduce your braking.
As above, I don't think the R550 will set up as a mid profile, but i would avoid thin pads and I would deploy the thick spacer to set the arms as far apart as possible.

Brucey
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Re: Another canti brake question, hopefully an easy one!

Postby Brucey » 9 Jul 2016, 6:56pm

MikeDee wrote:The R550 is the best brake of all of them. They use ez to adjust pads. Stay away from the brakes that use unthreaded brake pad posts. They are a royal pain to adjust.....


when the bosses are close together, the advice to 'stay away from post mounts' is absolutely the reverse of what you should do IMHO; as Colin suggests a post-mount low profile brake will fit onto 60mm bosses and work as a mid-profile brake. This is probably the best option if you want high MA.

By contrast there isn't a bolt-mount brake made (with the exception of CX50/70 model) that fits well on narrow bosses. If you try to fit BR-R550 onto narrow bosses you almost invariably won't be able to articulate the brake blocks enough.

FWIW if you want to upgrade CX50 to CX70 spec (cartridge brake blocks) you can do so, you just need to buy road holders with an M5 threaded boss and swivel built into the holder.

cheers
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531colin
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Re: Another canti brake question, hopefully an easy one!

Postby 531colin » 10 Jul 2016, 7:31am

Brucey wrote:............FWIW if you want to upgrade CX50 to CX70 spec (cartridge brake blocks) you can do so, you just need to buy road holders with an M5 threaded boss and swivel built into the holder........


I know this has been discussed before, but i can't remember the outcome?
CX70 has its own bushing that the brake arm pivots on, does CX50 have that too? (instead of pivoting on the frame boss)

Brucey
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Re: Another canti brake question, hopefully an easy one!

Postby Brucey » 10 Jul 2016, 9:32am

Image

Image

IIRC the brake blocks are different, but arms are the same on each brake, it is just the finish that varies?

cheers
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gerrymcm
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Re: Another canti brake question, hopefully an easy one!

Postby gerrymcm » 10 Jul 2016, 2:31pm

This is a mockup on my new forks with the CL510's (I'll get a real straddle/yoke before going out on the road :lol: )

Is this what is meant by "setting up the C510's as mid profiles"?

canti_setup2.jpg


This seems to be as close as I can lower the "imaginary" yoke without fouling the mudguards and the front rack mount.

I've bought some of these to go on these brakes.
http://www.clarkscycles.com/index.php/h ... -brake-pad

clarks_cp522.jpg
clarks_cp522.jpg (5.69 KiB) Viewed 1163 times


Any comments on the this setup would be appreciated.

I'll be honest and say I can't understand 90% of what's been written on the MA of brakes but will invest a bit more time into when I can.

Thanks very much.
gerry

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gaz
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Re: Another canti brake question, hopefully an easy one!

Postby gaz » 10 Jul 2016, 2:58pm

gerrymcm wrote:Is this what is meant by "setting up the C510's as mid profiles"?
Image

IMO yes.

gerrymcm wrote:I've bought some of these to go on these brakes.
Image

The assymetric post means the block extends back past the front of the fork blade. If they'll squeeze between the rim and the fork blade all is well.

If not Koolstop cross pads provide a solution. Available from Spa, be careful to select the unthreaded variety.
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