Weight weenie report. Dia Compe 980 brakes

[Bill Lindsay]

I've got a road build coming up that will use cantilever brakes.  I've got a TON of cantilever brakes in my stash, but even so I decided to buy more.  I really like the super simple, minimalist design of the Dia Compe 980s that Riv now sells.  I decided to buy two bikes worth and I'm going to shape and polish one set.  They seem about as light as cantilever brakes can possibly be, so I decided to do a weigh-off compared to some Paul Touring cantilevers in my parts box.  I weighed two arms, with springs, and with the mounting bolts.  I did not include straddle cables or straddle hangers or brake pads.  Arms to arms, the 980s are a few grams lighter 82g vs 91g.  I'll post photos and updated weights after they are polished.  After I've got them on my new build, I'll report back on how well they work.  I like that they are forged, light and cheap.  Hopefully I can polish them pretty, and hopefully they work well. 

Bill Lindsay

El Cerrito, CA

[John G.]

Any thoughts on the vertical adjustability of the pads? Wondering if they’d suit a 27inch to 700c conversion. I guess Canti post spacing is also an issue that is have to consider.

[Bill Lindsay]

I have no specific thoughts about the 980 suitability for a 630 to 622 conversion.  My general thoughts are that 630 to 622 conversions with cantilever brakes are always massively compromised, and I'd personally never bother with such a project.  If I was helping a friend who was dead-set on such a project, I would use vintage style brakes that use post style brake pads.  Like from my parts box I have some vintage Shimanos that I'd try. 

Bill 

On Wednesday, August 22, 2018 at 10:50:33 AM UTC-7, John G. wrote:

[John G.]

Thanks. You're right. I revisit the idea of a 630 to 622 conversion periodically, and always walk away immediately. 

In any case, looking forward to your thoughts on the 980s on your road build.

[Belopsky]

Very cool. I bet they stop well and are 1/4th the price of Paul.

RBW seems to be the cheapest place (and one of the only online from what i've found) to stock at current

[Paul Clifton]

Hey Bill,

What are the compromises converting 27 to 700?

I've never had a problem with it, and I can fit fatter tires, but I've only done it to a couple bikes.

Paul in ATL

On Wednesday, August 22, 2018 at 2:15:45 PM UTC-4, Bill Lindsay wrote:

[Bill Lindsay]

Paul

Please don't misunderstand me.  I specifically referred to converting from 27" to 700c on cantilever equipped frames. If the cantilever posts are in the right place for 630mm rims, you have to run the pads quite low for 622mm rims and the mechanical advantage gets all messed up, forcing compromises on braking performance, or brake feel, or brake equipment choices or brake setup choices or some/all of the above.  If you want me to comment on your two bikes, I'd be happy to look at your photos and run the numbers.  Basically, you'd want to start with a bike that was built wrong (in the right way). 

Don't confuse my comment with a general statement about 27" to 700c conversions.  For centerpull and sidepull brakes, I think it's usually straightforward and usually awesome.

Bill

[Bill Schairer]

Compass claims their Rene Herse to be 75g if you want to shave off another 7g per wheel. Don’t know what the $/g might work out to be...

Bill

[Bill Lindsay]

Compass brakes are $300 for two wheels.  Dia Compe 980s are $52 for two wheels.  The price difference is $248.  If the weight difference is 7g per wheel, then that would make that $17.71 per gram.  When I'm going weight weenie, I'm looking for $1/gram opportunities.  If I can throw $450 at my bike and drop a pound, that's a $1 per gram opportunity, and might be worth doing.  When it gets into the $5 per gram range, and would cost an additional $2000 to drop one pound, I'm usually out at that point.  $17 a gram is pretty dear.  If I ever bought Compass Cantilevers, it would be for beauty and performance, and the fact that they are not heavy. 

[lconley]

The difference between 622 and 630 is 8mm in diameter and 4mm in radius. The 622 pad will be 4 mm (1/6 inch) closer to the canti post than the 630. If it is within the range of the standard slot for pad mounting, it is not a problem - every pad slot on a brake arm that I have seen was considerably longer than 4mm. I would not worry about 4mm upsetting the brake balance or feel. A 650b conversion from 700c using longer side or center pulls is a much more radical change to caliper ratio, and they seem to work pretty well.

Also remember that you can play around with the cantilever straddle cable length to change the brake pull ratio - a slightly longer straddle cable will cancel the 4mm pad closer to the pivot. Don't ask me to do the math - Google Sheldon Brown.

The only problem that I have ever had with a 27 to 700c is on my P-15 Paramount, normal reach Campagnolo Nuovo Record sidepull on the rear with a Campagnolo dropbolt reaches a 27 x 1 but not a 700c (nor a 27 x 1-1/4) - When you are on the limits of the brake arm slot, the rim width can come into play. Back in the mid 70s all we had was 700c sewups and 27" clinchers, no 700c clinchers. Many bicycles had greater tire clearances in the rear than the front (thus the mixed Weinmann and later Dia-Compe 750R, 610F centerpull brake sets). I actually have Dia-Compe 750R, 610F centerpull brakes on a couple of Rivendells. 750s are 14mm longer than 610s - again I wouldn't worry about 4mm if it bolts on with no modification.

Laing

Cocoa FL

[Craig Montgomery]

I've converted 3 or 4 27" canti-bikes to 700c over the decades. Zoomed down mountains fully-loaded. Never died. 

Craig in Tucson

[John G.]

I think I hijacked this thread. Apologies. I’ll DM next time.

[Bill Lindsay]

Haha, don't worry about it. It's just a few old timers trying to show off how much we know. Nobody has said 'get off my lawn' yet.  The Riv-content remains: Dia Compe 980 brakes are subjectively nice looking, objectively light weight, objectively inexpensive, and objectively in-stock at Rivendell Bicycle Works in Walnut Creek, California.  The jury is split on 630 to 622 canti-conversions, and at least one of us is objectively not-dead. 

Bill Lindsay

El Cerrito, CA 

[R. Alexis]

The new Dia-Compe 980 brakes look interesting. I have the original Dia-Compe 980 brakes, http://velobase.com/ViewComponent.aspx?ID=D2AA4D24-29A3-4F50-B3CD-C789F21E144E&Enum=117&AbsPos=144 in use on my 1994 Bridgestone MB-1 retro build and on my 1987 Schwinn Voyageur 27" to 700c conversion. Don't know why Dia-Compe didn't come up with a different model# for these brakesh.

As for the 27" to 700c conversion, it may be a case by case issue on how well it works. When I initially built this frameset up I used some hybrid wheelset and Dia-Compe 984 brakes. The brakes didn't allow for the pads to hit the rims squarely. I still rode it. When I sold the bike I mounted some high profile Shimano Deore DX post style brakes. When I got the bike back and revamped the build I mounted some 980 brakes. These work well in use. The front have to be adjusted to the point that the brake arms angle slightly downward. I have a Dia-Compe quick release roller straddle cable carrier along with quick release TRP RRL brake levers help in getting the brakes unhooked for wheel removal. With both quick releases it is possible to get the brakes open enough so the wheel can clear without unhooking the brakes from the straddle cable.

Reginald "Another Old Timer" Alexis

[Harald Kliems]

I'll be curious to hear how they compare with Tektro CR-720s. I'm reasonably happy with mine, but the Diacompes are certainly prettier and also shave off a bit of weight. And people have complained that the Tektro has too much flex/play.

 Harald in Madison (WI)

[Bill Lindsay]

I took one bare arm and my smallest file with me on my commute today for some meditative filing.  I knocked out the forge parting lines pretty quickly.  Now is time for the biggest aesthetic decision:

Do I remove the "Dia Compe" that is forged in?  It's not deep, so it wouldn't be terribly difficult, and the thinning would be very JPWeigle-esque.  I'm not one of those anti-branding zealots, though.  I'm leaning towards erasing the "Dia Compe" 

Bill Lindsay

El Cerrito, CA

[lconley]

If I can remove the branding with Simichrome, I usually do. - Tektros were usually good for that before they started using paint instead of polishing the aluminum. IRD derailleur clamps and Microshift derailleurs too.

I remember the old Universal brakes that put blue paint in the recessed branding.

Laing

Cocoa FL

[Belopsky]

What brake levers do you plan on using with these brakes?

[Bill Lindsay]

Igor asked which brake levers I’ll be using.

I will use either SRAM S500 or S900.

Bill Lindsay
El Cerrito Ca

[Paul Clifton]

Got it. I noticed the canti clarification as I clicked post, but I still wasn't sure why it mattered. Makes sense now. My canti conversion to 622 is the worst stopping bike I have, but there are so many potential reasons for that (pads aren't nice, cable hangers are whack, straddle cable hanger is also whack, cables haven't been adjusted since I built the bike, etc.). I'll try adjusting things before I write it off. The pads hit the rim just fine at least. I'm using some of those old Shimano cantis that everyone recommends. Anyway, I'll keep the MA in mind when I adjust things, but no need to share photos of my brake butchery at the moment. Sorry for derailing the thread.

Paul

[Mark in Beacon]

On Thursday, August 23, 2018 at 4:44:37 AM UTC-4, R. Alexis wrote: Don't know why Dia-Compe didn't come up with a different model# for these brakes. 

I have been thinking the same thing, as they have no relationship to the original other than the name of the company that makes them. Both the design and the look are fundamentally different, and the new brakes, like most modern cantis, will get hung up on the fork blades or the seat stays, limiting the tire width; in fact, Rivendell recommends the Shimano CX50s for anything over 45mm. The original design keeps the brake blocks in front of the braze-ons, so the brakes can open all the way. Ironically, that feature--being able to open fully like old-style cantis-- is what Riv used to tout about the CX70-CX50 brakes, though I see that has been removed from the description. Riv's ad copy says they are a much improved version, but the only potentially objective statement supporting this statement seems to be "far, far, better brake shoes." Of course the originals could be upgraded with far, far better brake shoes as well.

I look forward to seeing what kind of carving Bill does, as I am somewhat underwhelmed with aesthetics of the "new" 980 and prefer the styling of the originals. Then again, while it seems they often not fondly regarded in terms of looks, I find the simplicity and angularity of the CR720s to be quite attractive, and they also carry out in a timely manner the cessation of the spinning of the bicycle wheels required of them.

[Bill Lindsay]

I've made a bit of progress on the first of four brake arms.  Here's a photo of the before and during.  I've filed off enough material to make the Dia Compe stamped-in logo go away, and to make that front face of the arm more of a continuous curve.  I'm still at 400 grit, so I haven't really begun the smoothing and polishing part of the process.  I might go back with the file and remove more material, possibly to make it taper down a little narrower where the cable end goes in. 

Bill Lindsay

El Cerrito, CA

On Wednesday, August 22, 2018 at 10:38:49 AM UTC-7, Bill Lindsay wrote:

[Belopsky]

Nice!

I got my set it from RBW yesterday and installed today. Going to take a bike around the block and report back on how well they work with Tektro RL340 levers..

[Belopsky]

Ride report: Seem to work well. I'll swap for Kool Stop pads eventually. 

[Max S]

What’s the optimum post spacing (on fork and stays) for these?..

- Max “they don’t make them for narrow posts anymore” in A2

[Mark in Beacon]

It depends somewhat on rim width, but I think around 80-85 is generally what most v-brake/canti posts are set at these days? Builders will know, but I believe I read 80mm suggested on a framebuilding forum (Curt Goodrich?). That's what I used for my spacing when I redid some posts for a conversion. I'm running Tektros and they fit fine. Maybe a bit more for really wide rims?

[Garth]

   Max,  Any cantilever intended for a cyclocross frame is by nature for narrow spacing.  

You might try a Tektro CR 710 for example. These are easy on the pocketbook AND work well. I replace all Tektro pads with Kool Stop blacks or salmons even before installing. I have this brake on my Bomba front and it's fantastic. Very firm, immediate response and strong braking, no squishies.  It would also work on my canti road bike with narrow spacing, which I currently use SunTour XC Pro and those are outstanding !  

The CR710 seems to get overlooked for whatever reason compared to the 720, which on the Bomba was decidedly "just okay".  

On Tuesday, August 28, 2018 at 10:20:16 PM UTC-4, Max S wrote:

[Belopsky]

FYI these work better than other brakes I've had, but perhaps it's the lever. I have not put KoolStop pads on the Dia Compe 980 yet. Any suggestions for which? I am thinking just the Supra, same as I have on some V-brakes unless there is a better type to use on V-brakes and I'll swap

[Max S]

Garth,

I agree that the 720 is a good brake and a good value. In fact I have it installed on one bike, but had to move all of the spacers / washers to the outboard side of the pad holder bolt, because the canti posts are closer to each other than currently standard. It actually works fine, but just — at the limit of the adjustment range for the brake. Just wondering if there is a simple and inexpensive option that works better (besides the old XT cantis).

While we are on this tangent of narrow post spacing, are there V or mini-V style brakes that work better than others in this instance?..

- Max “narrow (post) minded for the moment” in A2

[phil k]

Got a pair in.

So far it's been a breeze to set up, but I ditched the straddle hanger for moon units. The spring tension seems pretty even out the box. Did not have to adjust spring tension at all so far. So in that sense, it was just slightly easier to set up than the Paul Neo Retros. Can also adjust toe in.

Initial impression - less braking force than Paul Neo Retros, but not as grabby either. I think for a road bike it's a great option, but I would pick the Neo Retros for dirt/off-road applications. I don't feel the need to switch pads at the moment, but haven't been able to put its paces through any rain yet.

[Garth]

Max, Apparently my reply may have been misread as I pointed to the CR710 for narrow spacing(they are designed for cross bikes with 33mm+/- tires), not the 720.   The 710 costs about $20-25 each.


https://www.tektro.com/products.php?p=46

[David Hays]

Does anybody know if these will work with the RB-T?

Thanks.

David Hays

Williamsville, New York 

[Dave Redmon]

My 1991 RB-T bike was stolen a couple years and I found a 1994 RB-T to replace it. Cantilever post widths are significantly different. I can fit a number of brakes to my 1994 fork that would not fit my 1991 fork.

Dave in Kansas

[David Hays]

My RB-T says Synergy on the crossbar and the last of the serial number is 0121039. Anyone know what year this would be?
Thanks

David Hays
Williamsville, New York

> On Mar 25, 2019, at 12:53 PM, Dave Redmon <daver...@hotmail.com> wrote:
>
> My 1991 RB-T bike was stolen a couple years and I found a 1994 RB-T to replace it. Cantilever post widths are significantly different. I can fit a number of brakes to my 1994 fork that would not fit my 1991 fork.
>
> Dave in Kansas
>

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[Dave Redmon]

My 1991 frame was black and said Synergy. The 1992 frame was dark green, as I recall. 

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[David Hays]

Thanks. Just found this:

http://www.cyclofiend.com/notes/bsfaq.html

Identifying the year of my bike as well.

[Angelo Gatti]

Just saw this as I am in search of canti brakes without having to break the bank with the likes of  Paul's or Velo Orange (as nice as they are...).  I notices the 980's and am wondering what your experience has been with these.....

[David Hays]

Hi Angelo,

In just went out and checked my RB-t. I had gone with Shimano of similar style but not exeactly the same as my model and especially tight canti post clearances.

I have ordered a set of these for my Appaloosa that’s on it’s way.

I’ll let you know how they are.

David Hays

Williamsville, New York  

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