Hi LinusR and Brucey,
Thanks for your messages which is much appreciated!
So far I've taken the old brake cable off. It wasn't horrendously corroded or anything like that and it was in better condition than the gear shift cable that I recently took off and replaced on my bike because that was showing very obvious signs of corrosion.
I've now fitted the new cable and the braking motion is definitely smoother than it was before and so I'm pleased with that. At this stage I've actually used the old pads just for now. The reason that I did this is because I wanted to see what impact each individual change was going to make. I won't leave it too long though and the next time I'm giving it a good clean I'll change the pads as well.
Having put the pads back in and with the new brake cable I took it for a bit of a test run. Firstly I'd say that whilst on the work stand I definitely noticed the brake cable moving more smoothly. This has led to improved braking but it's not a night and day like change with a massive improvement. Therefore I'm keen to also see what change the new pads will make when I install them and have the benefit of both the new cable and the new pads.
When going for a test run checking the brakes I did wonder whether I'm being slightly unfair on the braking performance expecting too much in comparison to other brakes. The reason for this is I'm fortunate enough to have two bikes and the one that I use in the summer (plus some of spring & autumn) is a 2016 Kona Roadhouse and that has Shimano RS505 Hydraulic disc brakes and they definitely feel better than the Hayes CX Expert mechanical disc brakes on the Genesis Day One. But that is probably an unfair comparison because I'm not comparing apples with apples by trying to compare hydraulic to mechanical disc brakes.
Therefore just as the only other comparison/ reference point I have I also took my wifes sit up & beg step through frame bike out for a quick spin. That bike has calliper pull brakes and I'd say that the Hayes CX Expert mechanical disc brakes felt better than the calliper pull brakes on my wifes bike.
In the past I've always wondered if my Day One would have better braking with a change to say the TRP Hylex hydraulic disc brakes ( https://www.trpcycling.com/product/hylex-rs-post-mount/ ) but that would be an expensive change and not likely one that I can actually justify cost wise.
Once again thanks for all of the help, advice and support which has been invaluable whilst I've been tackling this job on my bike for the first time.
Thanks,
John
Rear mechanical disc brake adjustment on a bike with horizontal rear dropouts
Re: Rear mechanical disc brake adjustment on a bike with horizontal rear dropouts
when you fit the new pads it isn't a bad idea to give some consideration to the idea that the old pads (and the disc) may be suffering a little contamination; that the old pads are distinctly black-looking suggests that this might be the case. Now, sintered pads are high friction and a little more tolerant of slight contamination (and indeed can be more easily cleaned than other pad types) but the rear disc tends to get contamination on it even when the front is OK. This seems to come from two main sources;
1) splashes of chain lube. (if you keep the hub barrel clean, you will see if any splatters of chain lube get onto the hub quite easily, and this will tell you the disc is also at risk of contamination).
2) road film; the roads are often contaminated with oil and diesel; this gets lifted by the rain and spray from the front wheel goes all over the rear disc. It isn't unusual for a commuting bike to need the rear disc cleaning a couple of times a year when the front needs no attention. (you can tell that there might be that sort of contamination present if the LH chainstay appears to have a somewhat slimy film of crud on it; the same stuff will be over the disc too).
If there is even a slight amount of oil or diesel on the disc the brakes will be terrible. Organic/resin pads are pretty well impossible to clean properly. You can degrease the disc but if the disc has been hot with the muck on it, it can bake into a kind of varnish that won't easily come off in solvent but will still cause the brakes to be poor. If you abrade the surface of a used set of pads, so that the pads look like clean material (often buff-coloured if they are resin type pads) and then use the pads for a short while, if the pads pretty soon turn black this is a pretty good sign that there is some contamination present.
When you fit new pads there will be a bedding-in period; follow the manufacturer's instructions for bedding the brake pads in, and don't expect full braking performance until the bedding in procedure is complete. Note that your rear disc on an Alfine hub ought to be a centrelock one (or one on a centrelock adapator). Note that some shimano centrelock discs are marked 'use resin pads only'; these won't accept use with sintered pads, not without abnormally fast wear arising.
cheers
1) splashes of chain lube. (if you keep the hub barrel clean, you will see if any splatters of chain lube get onto the hub quite easily, and this will tell you the disc is also at risk of contamination).
2) road film; the roads are often contaminated with oil and diesel; this gets lifted by the rain and spray from the front wheel goes all over the rear disc. It isn't unusual for a commuting bike to need the rear disc cleaning a couple of times a year when the front needs no attention. (you can tell that there might be that sort of contamination present if the LH chainstay appears to have a somewhat slimy film of crud on it; the same stuff will be over the disc too).
If there is even a slight amount of oil or diesel on the disc the brakes will be terrible. Organic/resin pads are pretty well impossible to clean properly. You can degrease the disc but if the disc has been hot with the muck on it, it can bake into a kind of varnish that won't easily come off in solvent but will still cause the brakes to be poor. If you abrade the surface of a used set of pads, so that the pads look like clean material (often buff-coloured if they are resin type pads) and then use the pads for a short while, if the pads pretty soon turn black this is a pretty good sign that there is some contamination present.
When you fit new pads there will be a bedding-in period; follow the manufacturer's instructions for bedding the brake pads in, and don't expect full braking performance until the bedding in procedure is complete. Note that your rear disc on an Alfine hub ought to be a centrelock one (or one on a centrelock adapator). Note that some shimano centrelock discs are marked 'use resin pads only'; these won't accept use with sintered pads, not without abnormally fast wear arising.
cheers
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~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~
~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~
Re: Rear mechanical disc brake adjustment on a bike with horizontal rear dropouts
Hi Brucey,
Many thanks for your message above and given that I'd fitted the new cable and wasn't happy with the braking performance I am now fitting the new pads that I bought. As I mentioned I wanted to do the jobs of changing the cable and changing the pads separate & in isolation from one another just to see what difference each stage made.
Also given that this bike is an all year around all weathers commuter bike it's most likely that the pads are covered in all sorts of road grime and contamination. I appreciate that I could perhaps clean up the old pads but I've absolutely no idea whether they are organic or sintered and because in the past I've always asked LBS to check the brakes and replace parts when/where necessary but I've not been in control of what has been fitted. Therefore given the wear on the existing pads it seems to make perfect logical sense to now fit the new pads and hopefully this will improve the braking.
Anyway I've fitted the new sintered pads this afternoon and I've refitted the rear wheel. At this stage I've not adjusted the inner pad yet because I understand it you want to adjust the outer pad first because that's the one that doesn't move and is static once the caliper is fixed in place.
But I've got a bit stuck at the moment and I think that I might know what to do next but I just wanted to ask if I'm thinking along the right track.
Basically the outer pad is touching the disc rotor and rubbing as the wheel rotates and I can't see any gap whatsoever between the pad and the rotor. Am I right in thinking that the only way to address this is to change the position of the caliper by loosening the bolts holding the caliper in place and then moving the whole caliper outwards to create a gap in-between the outer pad and the rotor before tightening it back up again? Then you move onto adjusting the inner pad?
If I'm thinking along the right lines of my next steps to take can I ask a question about how to do this.
In order to move the caliper do I need to firstly need to undo the brake cable so that all of the tension is taken out of the cable and it's just completely loose? If I didn't have to take this step that would be good because I'd previously got the cable just where I wanted it secured and the lever pull feeling alright. But if I have to loosen off the brake cable in order to do the job properly then that's what I'll do because I want to get the job done right.
Also just out of interest the original disc brake rotors and hubs, front & rear, were both 6 bolt disc and that is still the case with the rear which has a 160mm Hayes disc rotor fitted (he rotor has Y13 and the letter E written on it) however the front disc rotor on my bike is now a Shimano centrelock disc rotor which was fitted after I got the front hub changed to a Shimano dynohub.
Thanks again for any help & advice to help guide me through this and get this job finished off and the bike back on the road which I can't wait for!
John
Many thanks for your message above and given that I'd fitted the new cable and wasn't happy with the braking performance I am now fitting the new pads that I bought. As I mentioned I wanted to do the jobs of changing the cable and changing the pads separate & in isolation from one another just to see what difference each stage made.
Also given that this bike is an all year around all weathers commuter bike it's most likely that the pads are covered in all sorts of road grime and contamination. I appreciate that I could perhaps clean up the old pads but I've absolutely no idea whether they are organic or sintered and because in the past I've always asked LBS to check the brakes and replace parts when/where necessary but I've not been in control of what has been fitted. Therefore given the wear on the existing pads it seems to make perfect logical sense to now fit the new pads and hopefully this will improve the braking.
Anyway I've fitted the new sintered pads this afternoon and I've refitted the rear wheel. At this stage I've not adjusted the inner pad yet because I understand it you want to adjust the outer pad first because that's the one that doesn't move and is static once the caliper is fixed in place.
But I've got a bit stuck at the moment and I think that I might know what to do next but I just wanted to ask if I'm thinking along the right track.
Basically the outer pad is touching the disc rotor and rubbing as the wheel rotates and I can't see any gap whatsoever between the pad and the rotor. Am I right in thinking that the only way to address this is to change the position of the caliper by loosening the bolts holding the caliper in place and then moving the whole caliper outwards to create a gap in-between the outer pad and the rotor before tightening it back up again? Then you move onto adjusting the inner pad?
If I'm thinking along the right lines of my next steps to take can I ask a question about how to do this.
In order to move the caliper do I need to firstly need to undo the brake cable so that all of the tension is taken out of the cable and it's just completely loose? If I didn't have to take this step that would be good because I'd previously got the cable just where I wanted it secured and the lever pull feeling alright. But if I have to loosen off the brake cable in order to do the job properly then that's what I'll do because I want to get the job done right.
Also just out of interest the original disc brake rotors and hubs, front & rear, were both 6 bolt disc and that is still the case with the rear which has a 160mm Hayes disc rotor fitted (he rotor has Y13 and the letter E written on it) however the front disc rotor on my bike is now a Shimano centrelock disc rotor which was fitted after I got the front hub changed to a Shimano dynohub.
Thanks again for any help & advice to help guide me through this and get this job finished off and the bike back on the road which I can't wait for!
John
Re: Rear mechanical disc brake adjustment on a bike with horizontal rear dropouts
if you back the cable adjustment off fully (and/or loosen the pinch bolt) and the outer pad still touches the disc, then you will need to move the caliper on its mounts.
The detail is different but the procedure as per the Hayes manual (link upthread) can be used, plus there are various methods of setting BB5 and BB7 calipers, which are vaguely similar too.
cheers
The detail is different but the procedure as per the Hayes manual (link upthread) can be used, plus there are various methods of setting BB5 and BB7 calipers, which are vaguely similar too.
cheers
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~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~
~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~
Re: Rear mechanical disc brake adjustment on a bike with horizontal rear dropouts
Hi Brucey,
Many thanks for your message!
I backed off the cable adjuster and also loosened off the pinch bolt on the brake cable and the rotor was still rubbing on the new disc brake pad.
Therefore I took the wheel out and loosed the bolts on the caliper and pushed it outwards as far as it would go. To be honest it was already almost as far over as it would go and so I wasn't able to gain much extra room. But I did get the caliper out a tiny fraction which has helped. Having reinstalled the wheel I still haven't really got much of a gap between the rotor and the disc brake pad but the wheel is moving more freely than it was and given that the caliper is pushed out as far as it will go I think that this is a good as it will get.
Therefore I then adjusted the inner brake pad and tighten the brake cable back up and took it for a test run and it all seems to be working alright. I did the repeated braking to bed in (or is it burnish) the new pads.
Fingers crossed it's all good from here and back to commuting duties for this bike.
Many thanks for all of your help which has been invaluable!
Cheers,
John
Many thanks for your message!
I backed off the cable adjuster and also loosened off the pinch bolt on the brake cable and the rotor was still rubbing on the new disc brake pad.
Therefore I took the wheel out and loosed the bolts on the caliper and pushed it outwards as far as it would go. To be honest it was already almost as far over as it would go and so I wasn't able to gain much extra room. But I did get the caliper out a tiny fraction which has helped. Having reinstalled the wheel I still haven't really got much of a gap between the rotor and the disc brake pad but the wheel is moving more freely than it was and given that the caliper is pushed out as far as it will go I think that this is a good as it will get.
Therefore I then adjusted the inner brake pad and tighten the brake cable back up and took it for a test run and it all seems to be working alright. I did the repeated braking to bed in (or is it burnish) the new pads.
Fingers crossed it's all good from here and back to commuting duties for this bike.
Many thanks for all of your help which has been invaluable!
Cheers,
John
Re: Rear mechanical disc brake adjustment on a bike with horizontal rear dropouts
if the brake pad continues to rub despite the changes you have made, adding a very thin washer between the locknut and cone on the LH side of the hub should space the disc further away from the disc caliper mount, and bring it back into the adjustment range.
The other thing you can do is to modify the brake caliper mount. There are three main options here; a) further ovalise the holes in the caliper itself (best not to overdo this one) or b) file the unused thread tops off the M6 mounting bolts; if you remove the thread tops where they are within the thickness of the caliper itself it won't weaken the bolt in the slightest but you will gain a little more clearance. A further option c) is to modify the adapter where it bolts to the frame; reducing the width of the adaptor slightly (best machined rather than filed) or machining the frame slightly will do this, eg taking the paint off or having the disc mount properly faced (which I bet hasn't been done before) will do this.
cheers
The other thing you can do is to modify the brake caliper mount. There are three main options here; a) further ovalise the holes in the caliper itself (best not to overdo this one) or b) file the unused thread tops off the M6 mounting bolts; if you remove the thread tops where they are within the thickness of the caliper itself it won't weaken the bolt in the slightest but you will gain a little more clearance. A further option c) is to modify the adapter where it bolts to the frame; reducing the width of the adaptor slightly (best machined rather than filed) or machining the frame slightly will do this, eg taking the paint off or having the disc mount properly faced (which I bet hasn't been done before) will do this.
cheers
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~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~
~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~