Better brake blocks.

[slowster]

No, you can't do that with the Tektro Gizmo, see Brucey's explanation in the thread linked above.

Brucey's posts in that thread seem to me to address how to fit the Power Hanger irrespective of the type of cantilever. It does not appear to me that Brucey was suggesting that the explanation CJ provided of how to determine the mechanical advantage of cantilever brakes would not apply in essence similarly to the Power Hanger.

The mechanical advantage of the brake in CJ's photograph was 2.8, calculated by dividing the 140mm 'straddle distance' by twice the height of the pad above the brake pivot (2 x 25mm). CJ's brake model looks similar/identical to the OP's, but the OP's straddle height is clearly higher.

CJ has also positioned the brake cartridges as far as possible towards the end of the studs. That minimises the reduction in 'straddle distance' - and thus also in mechanical advantage - that occurs as the pad moves closer to the rim.

I suspect the mechanical advantage of the OP's brake is a lot less than CJ's, and I suggest that the OP measures it - ideally both with the brake at rest and also with the brake lever squeezed to bring the pads against the rim.

Edit - On reflection, I think that a difference between an ordinary straddle cable and the Power Hanger, is that with the Power Hanger there should be minimal reduction in 'straddle distance' and mechanical advantage as the pad moves closer to the rim. The reduction in 'straddle distance' with a straddle cable occurs because the angle of the straddle cable changes during the stroke as the yoke rises, but the height of the Power Hanger is fixed, so the cable angle should remain largely unaltered through the stroke.

[Vetus Ossa]

Well I have no experience with canti brakes or the brake booster gizmo for that matter, the setup as is was a starting point.
The rear brake is set up with the supplied straddle wire and is just as bad as the front stopping wise.
Having read the comments above I am a little confused to be honest, do I move the brake pads in or out, and as for the straddle wire I think from pictures I have seen that’s the way it supposed to be. Why is it called a brake booster if it isn’t as good as the normal shimano one.
I thing I will try the brake blocks suggested by Colin 54 and see how that feels.

[rjb]

If you lengthen the straddle wire the brake arm rotates and moves the brake shoe further from the rim. Move the brake shoe further in to compensate. By the look of your pic the brake shoe is already touching the brake arm so you can only move it in one direction.
BTW you will need cantilever pull brake levers, not V brake levers which will pull too much cable and the lever may hit the bars before the brakes are fully applied.

[mattsccm]

Forgetting the science for a minute (which is correct ) I know from experience that those brakes work a darn site better with the arms much nearer to horizontal. If that means ditching the funny straddle wire then do it maybe. I just use the ends of normal cables, the nipple on one side and a suitable length for the rest.

[pwa]

Never used a "power hanger" but having spent ages trying to optimise cantis, fully agree that they'll never work, regardless of blocks, with a straddle cable at that angle.

It's definitely not the blocks.

IME unless brand new, there's not a huge amount to choose between blocks anyway.

As a long time canti user, the first thing I thought when I saw the pic was wow, that straddle wire (or whatever we are calling it) is very high. I'd not expect that arrangement to have any bite regardless of the blocks used.

[531colin]

Nothing much wrong with the pads. Here are some I have been hoarding for maybe 25 years, the bike I wanted the brakes as spares for is long gone, so i bunged them on this old Marin, they are much better than what was fitted originally. Brakes and pads have been in my loft, if they had been in the sunshine for 25 years it would be different.

IMG_5591 by 531colin, on Flickr

I would always recommend modifying your braking in the wet, if you aren't going to do that you might be a bit better off with something like Koolstop salmon, but there is nothing fundamentally wrong with shimano brake pads.

[531colin]

003 by 531colin, on Flickr

Thats the closest I ever got to a perfect cantilever setup. Braking was limited by my ability to keep the back tyre on the tarmac.

Its complete marketing twaddle to pretend that all you have to do is bung a "Power hanger" on your bike and your braking will be wonderful; it can't possibly work for all shapes of brake and fork, and even if it did it would still need setting up critically. I expect they sold boatloads of the things, its much easier to buy a gizmo than to learn how the brakes actually work.

Follow the setup method that slowster linked, and your brakes will work.
Unless you are looking for excitement, in which case, have fun!

Has anybody said, make sure you have levers for cantis, not Vee brakes.

[Cugel]

Cantilever brakes are sensitive little rascals requiring a careful set up to work as well as they should/could, as others have pointed out. Also, some designs (wide arm) are inherently better at braking for a given lever force than other designs.

Some brake blocks seem to get a better grip than others, although not in all weather conditions. The best I ever had were Dia-compe (no longer available) which seemed to be made of some sort of magic compressed Japanese grey mud, which broke down into a gritty sludge and stopped the bike well even in the wet albeit at the cost of lots of grey muck everywhere and brake blocks that had to be renewed rather often. And the rims wore faster as well.

Another tactic is to use wheels with rims that have a better grip on the blocks. I have a pair with the old Mavic ceramic rims, which not only never wear out but also provide a far, far better stopping drag with cantilevers fitted with all kinds of brake blocks. They do wear those blocks faster, though. Also, modern ceramic rims are rare and very costly. NOS ones seem to have disappeared.

Cugel

[Vetus Ossa]

What does the panel think of the setup now?

I have taken on board some of the comments and ended up here.
By the way I bought the gizmo as a problem solving bit of kit, not because I thought it was pretty, there was no space for the usual bracket on the headset and this seemed like a simple solution, as I didn’t want to spend much money on this bike, so will stick with it.
I have to admit the alterations have made a vast difference, and it actually does slow the bike down now. It may be as good as it gets, I have no basis for comparison as I have been using shimano hydraulic discs on my most used bike for the last five years and it will never match the stopping power of them will it.
I am ready to try going down under the bridge soon, the one where the lorry got stuck a few months ago, but will pick a quiet time as I want to be reasonably sure I can stop if a car is coming towards me.

[rjb]

Well done, I knew you could do it. I would let a bit more cable out on the left side (right if viewing from the front) just to get the brake booster more even. I know it's fiddly as you may have to cut a short length off the outer, and the curve from the lever is pushing it the wrong way. They are fiddly but if you persevere you will get there.
Are you off to Tesco's

[Vetus Ossa]

Thanks rjb...agreed, the left side needs a little more slack.
I walk to Tesco, this bike would never get me up the hill now alas.

[Jdsk]

Well done.

And congratulations to everyone who spotted the problem with the geometry.

Jonathan

[slowster]

It's great to see the excellent technical explanations and advice provided by CJ put into practice. I had doubted that the pads could be raised high enough in their slots to get the brake set up as you have, and I am pleased to be proved wrong (I should have realised it was likely to be possible based on CJ's photograph of what look like the same brake model).

A couple of suggestions:

Firstly, it looks a lot better now, but the straddle cable still has a fairly steep angle to the brake arms (again compare with CJ's photograph). If the steerer is 1 1/8", one option might be to fit a Problem Solvers 'Fender Flute'. Although they are designed to lower the height of mudguards on MTBs as per the photograph below, I think you could use it to provide a lower fixing point for your Power Hanger.

Secondly, if you do wish to try different brake blocks, I suggest you fit a pair of Clarks CP522 cartridges, and replace the pads in them with Kool Stop Salmon pads. Although marketed for V brakes, the cartridges have a smooth post (rather than threaded) and so will fit your brakes. These cartridges extend behind the fork blade. Therefore on a traditional tourer they may make it necessary to partially deflate the tyre to remove the wheel, but it looks like you have enough tyre/blade clearance on your MTB that that would be unlikely to apply.

Of these two suggestions, I think that lowering the Power Hanger would have a bigger impact than changing the brake pads.

https://www.sjscycles.co.uk/brake-block ... red-cp522/

https://www.sjscycles.co.uk/brake-block ... wet-muddy/



https://www.spacycles.co.uk/m19b0s190p3 ... nder-Flute

[Vetus Ossa]

It's great to see the excellent technical explanations and advice provided by CJ put into practice. I had doubted that the pads could be raised high enough in their slots to get the brake set up as you have, and I am pleased to be proved wrong (I should have realised it was likely to be possible based on CJ's photograph of what look like the same brake model).

A couple of suggestions:

Firstly, it looks a lot better now, but the straddle cable still has a fairly steep angle to the brake arms (again compare with CJ's photograph). If the steerer is 1 1/8", one option might be to fit a Problem Solvers 'Fender Flute'. Although they are designed to lower the height of mudguards on MTBs as per the photograph below, I think you could use it to provide a lower fixing point for your Power Hanger.

Secondly, if you do wish to try different brake blocks, I suggest you fit a pair of Clarks CP522 cartridges, and replace the pads in them with Kool Stop Salmon pads. Although marketed for V brakes, the cartridges have a smooth post (rather than threaded) and so will fit your brakes. These cartridges extend behind the fork blade. Therefore on a traditional tourer they may make it necessary to partially deflate the tyre to remove the wheel, but it looks like you have enough tyre/blade clearance on your MTB that that would be unlikely to apply.

Of these two suggestions, I think that lowering the Power Hanger would have a bigger impact than changing the brake pads.

https://www.sjscycles.co.uk/brake-block ... red-cp522/

https://www.sjscycles.co.uk/brake-block ... wet-muddy/



https://www.spacycles.co.uk/m19b0s190p3 ... nder-Flute

Thanks for the suggestions slowster.
If the steerer was 1 1/8" there are a couple of other options but unfortunately it's 1"

[slowster]

If the steerer was 1 1/8" there are a couple of other options but unfortunately it's 1"

Do you have an old quill stem that you will never use? If so, cut a section from the shaft, say around 50mm long, drill two holes in it and use that. Alternatively buy/scrounge a bit of 7/8"/22.2mm steel or aluminium tubing.