Canti power frustrations!

[531colin]

002 by 531colin, on Flickr

I think thats CR710...?
I was a bit underwhelmed....the design doesn't make it at all easy to get anything other than "narrow profile".
You can see in my photo where I had to file the brake arm and make up a different straddle wire barrel adjuster just to get the arms a bit wider than the design allows.

[531colin]

PLEASE have a look here....viewtopic.php?t=57410&start=30
I'm not tech. savvy enough to pick up a picture from that thread and post it here, BUT.......
In "cyclenut" post dated 10 Nov 2011, 6.50 pm, there is a photo of a narrow profile canti with 2 steel rules.
The horizontal steel rule passes through the centre of both pivots. The angled steel rule goes from the straddle bridge and passes through the cable attachment on the brake arm.

now heres the fun bit. where those 2 steel rules cross shows how wide a wide profile canti would need to be to generate the same MA as that narrow profile canti set up like that.

[Brucey]

this (post of 3.54) kind of underlines that these brakes won't work at all well on narrow-spaced bosses. I think it will not be possible to have the brake blocks bear on the rim at the right angle.

[Rhothgar]

Thought I’d posted just before Xmas to wish everyone a very Merry Xmas and Happy New Year.

Given the limited time I had, I had a lot of ‘fun’ playing around with different setups.

I got the Dia Compes working stupidly well in the end and without new blocks as yet.

I think it was beneficial to spend so much time trying different things as it gives you a better insight especially with the great advice given here.

I’m still not settled what setup I will go for.

Having re-read Brucey’s Boring McBoring’s guide again and looked to see what is currently available on Ebay, it made me think I may well just try the MC70’s Deer Heads I have.

Then again there is an ultra-rare set of Magura Hydraulic HS77 for sale on Ebay at present with an equally ultra rare price tag at £285 delivered!!!!! They would probably be nothing short of dangerous. Probably fine for a touring tandem where the chance of going over the bars is much reduced.

These weren’t the latest setup I had before taking the Dia Compe off as I managed to adjust the posts to be nearer to level.

I checked wheel dish and the wheel is perfectly central. Not much fun trying to set the brake pads but the final result was so much more powerful with a reasonable feel at the lever. Braking from the hoods provided adequate stopping power too which was a ‘FIRST’.

Going to polish up all the curved adjustment washers and remove any burrs in the arms where the washers have previously dig in slightly and try resetting the Dia Compe with some Kool Stop Salmon in a cartridge style post holder (just in case I end up opting for the BR-CX50) although there may well not be enough clearance for anything other than ‘Thinlines’.

Don’t ask me how the photo is actually in the correct orientation. Makes a nice change.

Of course, I am nervous about the straddle wire being so low so would probably raise that and end up with a good enough power and feel.

[Brucey]

the dia-compe brakes can be up on your frame with arms above boss height. This makes the brake (which btw is not safe with a conventional straddle and nothing to catch it in the event of main cable failure) weakly sensitive to straddle height, a little bit like a mid-arm brake is. I don't expect you to get MC70 arms as high as that; if so, the brake will never be as powerful. You might be better off sticking with the Alivio brakes.

[Rhothgar]

I'm just catching up Brucey.

You will no doubt have seen my post of the Boring McBoring's guide.

I'll briefly reiterate here for 531colin to see too.

Managed to source some CR720's. No good though as there are the older ones with the MTB V brake holders which are 70mm long. That's not an issue per se as I noticed they had nice narrow holders (this is despite not having seen your comment are Clarks brake shoe holders or modifying some Shimano ones with epoxy and a M6 bolt until today!).

What I particularly like about the CR720 design is the rotating anchor connection. Superb. Just like the Deore XT MC70's.

Unfortunately, it turned out that the CR720's are not suitable for 60mm bosses and 25mm rims. I can get them to work but the angle of the arm is too low. The upper leg of the arm should be horizontal or thereabouts. No such luck. I might try with my old worn Koolstop Thinlines to see if I have get a better angle before I try the Deore XT M730's I've just bought.

And my engineer mate knocked up his interpretation of the chain link idea you had. I am sure you said the link should be rotated up but he has cut them off because he said they wouldn't allow the cable to be gripped. I couldn't quite visualise what he was trying to explain to me over the phone.

I think the cable clamping here might cause too much of an eccentric load and thought your design called for the cable to go between the links? Again, I wasn't quite clear on that part of the description.

[[XAP]Bob]

Not having read the previous eight pages... has someone mentioned putting a mudguard under to protect in the event of a cable failure?

[Brucey]

...And my engineer mate knocked up his interpretation of the chain link idea you had. I am sure you said the link should be rotated up but he has cut them off because he said they wouldn't allow the cable to be gripped. I couldn't quite visualise what he was trying to explain to me over the phone.....

close but no cigar. My instructions were (I think) quite explicit and appear to have been ignored.

[Rhothgar]

Not having read the previous eight pages... has someone mentioned putting a mudguard under to protect in the event of a cable failure?

Yes. Don't panic Mr. Mainwaring!

I'm just playing with setup with lots of different cantis. I wouldn't ride it like that.

[Rhothgar]

...And my engineer mate knocked up his interpretation of the chain link idea you had. I am sure you said the link should be rotated up but he has cut them off because he said they wouldn't allow the cable to be gripped. I couldn't quite visualise what he was trying to explain to me over the phone.....

close but no cigar. My instructions were (I think) quite explicit and appear to have been ignored.

He is a beneficiary in my will. Maybe that has something to do with it...

This is where my own thought process broke down:-

5) fit a suitable M5 threaded pinch bolt.
6) the main brake cable can be sandwiched between two pairs of chain side plates.

Obviously the pinch bolt is intended to go through the drill hole and the double side plates.

But are the side plates meant to be crushed by the pinch bolt to grip the main cable?

[Rhothgar]

Also the Circles Calculator that has been posted about on numerous occasions and is dead can be found here:-

https://web.archive.org/web/20230811124 ... ntilevers/

I am not entirely sure if this is the complete calculator and what it looked like previously when the sliders were used because I never saw it originally before the site went down.

There is also a 6 page PDF blog I have downloaded.

[Brucey]

...But are the side plates meant to be crushed by the pinch bolt to grip the main cable?

yes, but if you don't like this, there is nothing preventing the use of spacer washers.

I think you could make a very good pinch bolt for this job, using an M5x10mm screw (ideally 8.8 grade or stainless). The method would be to add a blob of MIG weld to each side of the screw prior to drilling a 1.6mm hole (for the cable) between them, about 2mm away from the head. The screw can be SG'd so it still fits in a 5.05mm drilling and positioned so that the hole is correctly located between the sideplates, using shims if required. In use, the screw could be held via the head during tightening of the nut.