Advice please regarding potential mechanical disc brake upgrade

[Tenacious Sloth]

The brake cables on my used CAADX had already been upgraded to Jagwires by its previous owner.

I think they came new with Jagwire cables. Mine did anyway.

 

[vickster]

It's a shame the hydro hoods are so big and fugly!!

 

[ColinJ]

Hy-Rd's are quite particular about which levers they like, for optimum results it needs to be a pretty new shimano. I can't remember when and how many times shimano changed the pull ratio. I do know 5600 (and equivalent) doesn't work at all well, 5800 (all latest 11 speed) is brilliant. Can't recall if 5700 works or not, although it is a different pull ratio to 5600. I think the latest tiagra is 100% compatible too, but don't quote me on that.

Hmm ... Mine are the 10-speed Tiagra equivalent of 5600, the 4600. I think you are right - I just checked the pull again and nothing happens for the first 2/3 of the action. All of the braking comes in on the final 1/3 of travel and to get strong braking power I have to pull the levers to the bars! In fact, I think I am only getting about 80-90% of full power - I could still just force the wheel round standing next to the bike and pushing it forward. I can get that amount of braking with one finger and half the brake lever travel on my CAAD5 (Campag Chorus rim brakes)!

I think I might unwrap the bar tape, rotate the bars slightly forward and move the shifters back up to the equivalent of their current position. I would still have to pull the levers a long way but I should be able to pull the lever a few mm more to get that last 10-20% of braking.

It's a shame the hydro hoods are so big and fugly!!

I think my old Tiagra shifters already look pretty clunky compared to the svelte Campag gear on my CAAD5. Are the hyrdraulics really that much worse? (Goes off to Google for evidence ...) Ah, ok - they are ugly. Slightly more ugly than what I already have!

 

[ColinJ]

Hang on ... I just found THIS DISCUSSION on MTBR. I like the idea of rerouteing the cable - it would be easy to try that idea out!

I'll be back with the results later.

 

[vickster]

Hmm ... Mine are the 10-speed Tiagra equivalent of 5600, the 4600. I think you are right - I just checked the pull again and nothing happens for the first 2/3 of the action. All of the braking comes in on the final 1/3 of travel and to get strong braking power I have to pull the levers to the bars! In fact, I think I am only getting about 80-90% of full power - I could still just force the wheel round standing next to the bike and pushing it forward. I can get that amount of braking with one finger and half the brake lever travel on my CAAD5 (Campag Chorus rim brakes)!

I think I might unwrap the bar tape, rotate the bars slightly forward and move the shifters back up to the equivalent of their current position. I would still have to pull the levers a long way but I should be able to pull the lever a few mm more to get that last 10-20% of braking.


I think my old Tiagra shifters already look pretty clunky compared to the svelte Campag gear on my CAAD5. Are the hyrdraulics really that much worse? (Goes off to Google for evidence ...) Ah, ok - they are ugly. Slightly more ugly than what I already have!

All Shimano hoods are unattractive other than maybe Dura Ace, I like my slim SRAM mechanicals...the SRAM hydros are fugly too. All hydros look like big horns on the bike and not in a good way

 

[ColinJ]

Hang on ... I just found THIS DISCUSSION on MTBR. I like the idea of rerouteing the cable - it would be easy to try that idea out!

I'll be back with the results later.

Well, that was pretty successful!

I disconnected the front brake cable and cut/filed a new cable run for it on the opposite side of the bolt which attaches the cable to the small lever which operates the hydraulic part of the brake. I then went out for a very short test run which included a couple of small hills which let me give the brake a good test to compare its action with when I rode the bike on those same roads on Wednesday. On the previous ride I found that I couldn't really operate the brake satisfactorily from the hoods because I needed to pull the lever too far. This time it felt perfectly acceptable - I could get some braking with a smaller pull of the lever and enough braking with a 'reasonable' amount of pull. As for hard braking from the drops - I was managing to get the missing 10-20% of braking power without pulling the lever all the way to the bar. In fact, it would now be quite difficult to pull it as far as the bar. I am getting a lot of braking with the lever still having an inch or so of travel to spare.

Verdict: A good bodge!

I'll give the same warning as the poster who suggested the bodge in the first place ... Don't mess about with your brakes unless you are confident that you are competent to do so! If you do it and it all goes pear-shaped, that is your responsibility, not mine!

Here is a fuzzy photo of the bodged brake:

To make it more obvious what I did, and why it makes such a difference, take a look at this:

The dashed red line shows the original cable routeing, and the dashed green line the new arrangement. The solid lines show how much difference there is between the points at which the cable pulls. If you stop and think about it - a certain amount of cable pull moves the green line through a much bigger angle than the red line would move through, i.e. more braking is applied.

 

[midlife]

I'm not sure if that's how "mechanical and advantage" works?

 

[ColinJ]

I must be having to pull a bit harder, but that is not a problem. The problem was how far I had to pull the lever. I will happily pull harder for a shorter distance!

 

[Howyadoinoutthere]

Thanks to everyone who replied, the thread has encouraged me to have a go at the work myself. Interesting that the proposed option of upgrading to tpr spyres was overtaken by fitting the hy/rd to the front wheel instead. I think I will try that first as the cost is about the same.

Jeff

 

[ColinJ]

That's the spirit!

One thing that I forgot to mention is to make sure that you adjust the mount for the calliper so that the rotor is midway between the brake pads when the brake is not being operated. To do that slacken the mounting bolts (screws?), and apply the brake so it squeezes the rotor. The calliper assembly will move itself to the correct position. Fix it in that position by tightening the bolts while the brake is still applied. When you release the brake, you should see the pads retract to leave a small gap either side of the rotor.

There isn't a huge amount of clearance so try never to bash your rotor out of true or it will tend to rub on one or both pads as you ride along.

 

[I like Skol]

Can I just repeat my earlier comment? Before you spend £££s on new kit it might make a huge difference just optimising cable routing/alignment, making sure the caliper adjustment is spot on and fitting some new pads. The advantage of this is that it will work for both ends.
The improvement from fitting new hardware is going to be short lived if you just contaminate the new pads by spraying bike lube around willy-nilly.....

 

[Howyadoinoutthere]

Fair comment I like Skol. I'll try adjustments as you suggest to the existing set up first before committing to the hy/rd. I think I had written off the Promax Render R calipers because of the almost uniform criticism from users.

 

[ColinJ]

Fair comment I like Skol. I'll try adjustments as you suggest to the existing set up first before committing to the hy/rd. I think I had written off the Promax Render R calipers because of the almost uniform criticism from users.

I still have my rear Promax. Given yesterday's success with boosting the front HY/RD's performance, I might have another go at improving the rear brake. (It already works well enough for my purposes, but it would be interesting to see if I can make it better.)

 

[ColinJ]

I still have my rear Promax. Given yesterday's success with boosting the front HY/RD's performance, I might have another go at improving the rear brake. (It already works well enough for my purposes, but it would be interesting to see if I can make it better.)

A good tweak DID help! I took up more cable and adjusted the position of the fixed pad. I also decided to adjust the calliper position as I described above.

The main improvement to both brakes is that I can now get significant braking from the hoods without having to pull the levers too close to the handlebar.

 

[chriscross1966]

I run a TRP Spyre on one of my Bromtpons and like it enough that the dual-disc one I'm building will have them at both ends...It's quite telling that a few years ago all my LBS mechanics daily riders had Hope hydraulic brakes, now they all have TRP Spyre mechanicals... They're about as good as a mechanical can get, the twin-pivot action makes them a doddle to set up, especially if there are two of you, and the pads (let alone the rotors) seem to last forever...