Dia Compe GC700 brakes-any impressions?

[wood chuck]

I see Dia Compe has a new (to the USA) long reach center pull brake, called the GC700.  Has anyone used them, and what do you think of them? How much did you pay? Doing a 650b conversion on a Salsa Pistola and I'm not happy with the Tektro 559s with Kool Stop salmon pads. 

Thanks for any advice.

[Eric Daume]

I don't have any experience with that brake, but the reach only goes up to 70mm--that might not be enough for many 650B conversions (my Raleigh Technium needs at least 75mm)

Eric

On Sun, Jan 15, 2017 at 12:40 PM, wood chuck <dirtba...@gmail.com> wrote:

I see Dia Compe has a new (to the USA) long reach center pull brake, called the GC700.  Has anyone used them, and what do you think of them? How much did you pay? Doing a 650b conversion on a Salsa Pistola and I'm not happy with the Tektro 559s with Kool Stop salmon pads. 

Thanks for any advice.

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[Igor Belopolsky]

Where did you see them for sale? for the price id rather buy Paul Racers

[Harold Bielstein]

I think the GC700 will fit around a set of 42 mm tires whereas the Racers won't. As I recall the 700 will reach down to 70mm.

Sent from Hal's iPad

On Jan 15, 2017, at 2:59 PM, Igor Belopolsky <belopol...@gmail.com> wrote:

Where did you see them for sale? for the price id rather buy Paul Racers

On Sunday, January 15, 2017 at 12:40:32 PM UTC-5, wood chuck wrote:

I see Dia Compe has a new (to the USA) long reach center pull brake, called the GC700.  Has anyone used them, and what do you think of them? How much did you pay? Doing a 650b conversion on a Salsa Pistola and I'm not happy with the Tektro 559s with Kool Stop salmon pads. 

Thanks for any advice.

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[TomT]

Dia compe said Merry Sales should have them.  I contacted them about it and also about the specs of their rando bars- drop/ reach/ width at hoods etc. and they sent me a drawing of their racing bars instead.  ;)

[Igor Belopolsky]

The racers will clear 650*42 but the reach is 57-67

[nm matt]

yup, what igor said. i am using racers on babyshoe passes and 50mm Berthoud fenders. i had to file the slots for the pads to get a bit more reach, but are good stoppers even with the pads slammed, and then some...

[wood chuck]

Not sure just who is selling them in the U.S., but I saw them on J&B Imports consumer site-jbi.bike.

[satanas]

I googled them a few weeks back after seeing them on the DC site, and found a UK source, or maybe two. IIRC it was ~£55 per brake, but that included 20% VAT which should come off for exports.

While we're talking about centrepulls, does anyone know which out of the Paul Racer, Compass/Raid and GC700 has the most or least lateral space inside the caliper?
I gather that Racers aren't likely to clear ~51mm tyres (TBs) adequately, but might any of the others do so? I'd prefer to avoid cantis if possible.

Later,
Stephen

[Igor Belopolsky]

Well the problem with this comparison is.. not all of these are center pull..Like the Compass claim to have the best clearance, but you need to have them brazed-on..

[Stephen Poole]

They *are* all centrepull brakes, but some aren't available with centre-bolt mounting, ie Compass. Paul have some weird name for "attaches via a bolt like most other brakes" (centermount?) and I suspect that's causing confusion here.

As I understand it, the Paul brakes have somewhat bulkier springs and spring housings, and these thus consume more space on the inside than other brakes, not a problem with 42mm. Last year various people suggested the Paul Racers weren't likely to clear Thunder Burts or SBHs by enough. What I'm wondering is whether any of the other options (including the new GC700) might, or whether cantis are still the go.

I'd like to have the option of using a 54-584 Thunder Burt occasionally, but these are going to be more like 50mm wide on Pacenti Brevets which are what I'm likely to end up with. If that could be done (sans fenders) with centrepulls that would make some things a bit less messy.

Later,
Stephen

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[Philip Kim]

Paul's have 54mm space between pivots. I've fit SBH on them. No fenders.

Compass says 42 plus fenders. Know Jan likes 10mm space between tire and fenders I'm guessing at 52mm

[Stephen Poole]

On 17 Jan 2017 2:00 am, "Philip Kim" <phili...@gmail.com> wrote:
>
> Paul's have 54mm space between pivots. I've fit SBH on them. No fenders.

Thanks - good to know.  :-)

> Compass says 42 plus fenders. Know Jan likes 10mm space between tire and fenders I'm guessing at 52mm

I remember Jan saying at least 20mm above the tyre, but not anything about sideways clearance. If it's 10mm total then that's less than the 54mm for Paul Racers above, but if it's 10mm *each side* that's a different story...

Later,
Stsphen

[Igor Belopolsky]

Does this help?

https://www.compasscycle.com/wp-content/uploads/2015/05/Compass_brake_instructions_web.pdf

[Ray Varella]

Stephen,

      Measuring my Raids at the mounting posts (brazed on), I get 55mm inside to inside. 

From the brake arch to center of brake shoe posts I get 70mm and the pads are near the bottom of the slots. 

Height is going to be less of an issue than width. 

You could probably run SBH without fenders. 

Seems like anything with knobs would clog with mud, assuming it would even clear. 

Ray

Vallejo CA

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[Justin Hughes]

I'm curious. On most frames these larger centerpulls find themselves on, isn't the fork crown and resulting width between blades often going to be just about as limiting as the caliper? Or are these brakes being installed on bikes with the Pacenti MTB, old school Nova MTB crown or something else?

[Jeffrey Kane]

Maybe not the fork crown/width/height so much as I think a lot of frames end up limiting the tire width the seat stays behind the BB ...

[Adam Paiva]

Here is a SBH in a Paul Racer

[Evan Baird]

I think they were in a recent Merry Flyer, but they don't really eat their own dogfood so I'm not surprised they had no clue what you were asking about. The joys on working with non cyclists.

[satanas]

Thanks guys. I guess that means the corner knobs on Thunder Burts will hit the caliper or have basically zero clearance. It doesn't sound like the Compass/Raids are going to be much different, so it seems cantis are the sensible choice. They will definitely work.

Re crowns, etc: Assuming rim brakes, the most resilient blades are likely to be the Toei ones Jan sells, but these only fit the matching 53mm crown; I don't know anyone who's good at TIG welding, so crown modification is out for me. If a more normal 28x19 crown is used there are wider options like the Pacenti PBP (58mm), Pacenti MTB (68mm IIRC) and others. This might mean a bit less fork flex with narrower tyres due to larger section blades, but wider tyres can be used, complete with lower pressures, knobs, etc.

IMHO more options are good. A wider crown to fit the Toei blades wouldnt hurt either. :-)

Later,
Stephen

[Philip Kim]

have you thought about segment forks? the ocean air ramblers look really good with them.

[Justin Hughes]

They have them. They're not cheap. 

[Harold Bielstein]

I thought the Rambler used the Pacenti PBP crown.

Sent from Hal's iPad

On Jan 18, 2017, at 10:07 AM, Philip Kim <phili...@gmail.com> wrote:

have you thought about segment forks? the ocean air ramblers look really good with them.

On Wednesday, January 18, 2017 at 7:00:16 AM UTC-5, satanas wrote:

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[Stephen Poole]

@Philip: I know of nobody here in Oz who builds segmented forks, have no idea what tubing they use, and also have no idea how they ride. Everything is an unknown.  :-(

Re Pacenti crowns: These appear to be pretty much extinct now that Kirk has lost interest in framebuilding stuff; I suspect that what's floating around now is likely to be it. There are other wider crowns around that fit various blade shapes.

BTW, the 2016 Columbus catalog downloaded from Ceeway listed several disc brake fork blades, including some "under development" with incomplete details; all appeared to have thicker walls and larger ODs at the dropout ends, with assorted sections at the top.

Later,
Stephen

[Justin Hughes]

For what it's worth, Stephen, I am having a custom with high rake fork built right now that will use Switchback Hills or Thunder Burts with fenders and the option of 700x38 or 27.5x2.25 without. There are a lot of cool tires that will fit in a PBP crown that won't quite fit in a Grain Bois crown. I'm not sure what, if any, modification my builder will make to the stock crown. 

I missed the details of your project, but my hunch is that if you want a PBP crown you can get one. You could also just have a fork made by a US builder with the PBP crown and shipped to Oz. I suspect a lot of builders stocked up once it was known they would no longer be produced. 

Justin

On Wednesday, January 18, 2017 at 7:00:16 AM UTC-5, satanas wrote:

[Stephen Poole]

Thanks Justin,

I already have a PBP crown in a box with some True Temper tubes and other bits, but have been wondering about fork blades, brakes, etc, given everything has to fit together.

Later,
Stephen

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[Alex Wetmore]

Hahn Rossman got Columbus to draw nice long fork blades that are a good match for high rake forks with a PBP crown.  You can choose somewhat where to trim any tapered fork blade to control the ride quality as well.

https://framebuildersupply.com/products/columbus-cromor-rando-fork-blades-28x19-oval-9-wall-length-450

I'd guess that Ceeway carries them in the UK.

For low offset forks just pick something reasonably light that suits your luggage requirements.  One nice thing about centerpull brakes (vs cantilevers) is that the mounting bosses are supported by the fork crown instead of the blades, and the blades can be lighter than what would work well with cantilever brakes.

alex

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From: 65...@googlegroups.com <65...@googlegroups.com> on behalf of Stephen Poole <nsc.e...@gmail.com>
Sent: Wednesday, January 18, 2017 9:58:53 PM
To: Justin Hughes
Cc: 650b
Subject: Re: [650B] Re: Dia Compe GC700 brakes-any impressions?

 

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[Stephen Poole]

On 20 Jan 2017 6:09 am, "Alex Wetmore" <al...@phred.org> wrote:
>
> Hahn Rossman got Columbus to draw nice long fork blades that are a good match for high rake forks with a PBP crown.  You can choose somewhat where to trim any tapered fork blade to control the ride quality as well.
>

Presumably leaving all of the 40mm small diameter section at the dropout end would give the best ride, but might that leave things a bit thin where canti bosses would go?

>
> https://framebuildersupply.com/products/columbus-cromor-rando-fork-blades-28x19-oval-9-wall-length-450
>
> I'd guess that Ceeway carries them in the UK.
>

Those blades are listed in current Columbus catalogs and Peter at Ceeway seems to be able to get anything they make. He's very helpful too.

>
> For low offset forks just pick something reasonably light that suits your luggage requirements.  One nice thing about centerpull brakes (vs cantilevers) is that the mounting bosses are supported by the fork crown instead of the blades, and the blades can be lighter than what would work well with cantilever brakes.

Yes, agreed and I have set of centre-mount Paul Racers that could be used as is or converted to braze-on. The question is tyre clearance with these or any of the other centrepulls. I'd like to have the option of using tyres around 50mm (actual width) partly to raise the BB a bit for non-technical offroad use.

From the pics posted it looks like the widest point of the casing with SBHs ends up next to the brake pivots/springs, where there's the least clearance. Maybe this could be fudged a little by spacing the pivots a few mm further apart and using thicker spacers between the pads and brake arms. Any comments?

Ideally, I'd like to use the Columbus blades in a PBP or Pacenti MTB crown, trim the blades at the top only, use braze-on Paul Racers and have them adequately clear 54-584 Thunder Burts on Pacenti Brevet rims. Is there any reasonable chance this might be possible?

It would be better not to have to compromise on tyre size, especially since there's little or nothing between 42mm and SBHs or TBs, both of which have been reported to be 50-51mm in reality.

Later,
Stephen

[Ray Varella]

Has anyone made an inquiry to Paul's Components about whether he has plans to introduce a centerpulls with more clearance?

Since they machine their arms they may be in a better position to respond to the wants/needs of potential customers compared to a company that has to make forging dies for new arms. 

Just a thought. 

Ray

Vallejo CA

[Evan Baird]

I asked about that in 2008 at Nahbs.

[Evan Baird]

Has anybody seen pictures of these IRL? I've been keeping an eye out because I'm thinking about rebuilding my homemade frame.

[Mark Guglielmana]

I just used a set on a fork build-they are loooooooong! Even after bending 65mm of rake on a 5" radius form there was a lot left to trim. 

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[Mark Guglielmana]

1" PBP crowns are available, but the 1" Pacenti MTB crowns are not, except for a few builders that bought a bunch to stash away (and if anyone can tell me differently, let me know!), but you can still get 1-1/8". The PBP crowns are plenty wide for 42mm tires and fenders. I used a 1" Pacenti MTB crown on a gravel bike I built up using Rat Trap Pass tires and 60mm wide fenders. 

[Daniel Eells]

The 1" Pacenti MTB crowns are actually in stock at framebuildersupply in Portland.

https://framebuildersupply.com/collections/fork-crowns/products/pacenti-1-mtb-fork-crown-74mm-inside-width-biplane-design

Daniel

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[Daniel Eells]

I notice that the description says 1 1/8, but the item title says 1.  It looks like they carry both sizes.

Daniel