Stopping with mechanical disc brakes
#1
Senior Member
Thread Starter
Stopping with mechanical disc brakes
I have a 2012 Kona Sutra that came with mechanical disc brakes (Avid BB7 and Tektro 340 levers). In the 4 years that I have owned it (I bought it new in the fall of 2013), the brakes have never really been that great. The levers aren't bottoming out (but I could try to tighten them up a bit more), I've cleaned the rotors with isopropyl alcohol, I've cleaned the pads and I've replaced the pads too. My LBS seemed to think that I've done all I can with them and that mechanical discs are never as good as hydraulic (I have hydraulic on my mountain bike and they are much better, even though the two bikes are of similar quality so it is not like I'm comparing highend vs lowend bikes). Also, my LBS said that, at the time being, road-style hydraulic discs are very expensive.
Are the LBS opinions correct? Are there better quality road style mechanical disc brakes that I could consider? Are there "cleaning" options that I could try? Are there less expensive road style hydraulic disc brakes that I could consider?
Thanks
Are the LBS opinions correct? Are there better quality road style mechanical disc brakes that I could consider? Are there "cleaning" options that I could try? Are there less expensive road style hydraulic disc brakes that I could consider?
Thanks
#2
Check the housing - until only recently OEM were not that great about using the proper compressionless housing for mechanical discs.
Also, try using 120-200 grit sandpaper on your rotors. A lot of times alcohol won't remove the glaze/contaminant that can be present.
Also, try using 120-200 grit sandpaper on your rotors. A lot of times alcohol won't remove the glaze/contaminant that can be present.
#3
Banned
My BB7 (Mtn) worked better with aftermarket pads, than with the original ones.
Mine work just fine .. you seeking the ultimate brake? willing to pay Big Bucks?
Mine work just fine .. you seeking the ultimate brake? willing to pay Big Bucks?
#4
Senior Member
Thread Starter
Not seeking the ultimate brake, just better: my calipers on my 1988 Bianchi Strava work better than my mechanical discs. In an emergency, it is unlikely I'll stop in time.
#5
Senior Member
Thread Starter
Just happened to watch a YouTube video of a fellow who used a car disc brake (rotor) deglazer on his mountain bike rotors: spray on both sides of both rotors, ride up and down the road for a few minutes with the brakes on lightly, gradually pressing harder over the minutes. Rotors will be hot to touch and any squeaking (mine don't sqeak too much, nothing that really bothers me) will be eliminated. However, I'll try the sandpaper first.
#6
Banned
Now there is Low compression Housing, its like Indexed Shift Housing, just adding a Kevlar braided overwrap on the outside sheath,
to keep the spikes of braking force from bursting the housing..
(Shift cable housing has a more constant end force applied)
I got pads from Kool Stop , organic compound.. I'm not trying to go fast, Its a Rain braking benefit,
[160 disc, 20" 406 wheels, Bike Friday.]
....
to keep the spikes of braking force from bursting the housing..
(Shift cable housing has a more constant end force applied)
I got pads from Kool Stop , organic compound.. I'm not trying to go fast, Its a Rain braking benefit,
[160 disc, 20" 406 wheels, Bike Friday.]
....
Last edited by fietsbob; 10-30-17 at 02:08 PM.
#7
Senior Member
I recently went through this with Avid BB5's. BB5's are tuned similarly to BB7s, except that the small knob is missing. Is the brake arm fully relaxed when your brake lever is not pulled? I find that my BB5s exhibit bad modulation, if the brake arm is too far in (in the not-breaking state).
#8
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You've adjusted/aligned the brakes using park tool or avid recommended technique?
I find this very helpful: https://www.parktool.com/blog/repair...isc-adjustment
I find this very helpful: https://www.parktool.com/blog/repair...isc-adjustment
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#9
Senior Member
Thread Starter
You've adjusted/aligned the brakes using park tool or avid recommended technique?
I find this very helpful: https://www.parktool.com/blog/repair...isc-adjustment
I find this very helpful: https://www.parktool.com/blog/repair...isc-adjustment
I did a thorough cleaning with isopropyl alcohol last night and a thorough sanding/deglazing but to no effect. However, perhaps there is more movement of my brake lever than there should be (it is not bottoming out on the bar but a little less movement might be beneficial).
#10
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Only tool needed is a hex wrench. Needle nose pliers can be helpful, too. Park Tool makes bicycle tools. And offers useful repair/maintenance advice on their website.
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#11
Senior Member
my bb7's on a heavily loaded touring bike in steep mountains have performed flawlessy, with very good stopping power, and require so little finger pressure to get hard full stops from 50, 60kph compared to all my years touring with cantis in similar mountainous roads.
of course I cant comment on how your brakes are working, but I've been suitably impressed with BB7's being used in rather tough riding conditions (steep hills) and how they routinely hauled my touring bike down to a stop when I would spot a photo opportunity I didnt want to miss.
of course I cant comment on how your brakes are working, but I've been suitably impressed with BB7's being used in rather tough riding conditions (steep hills) and how they routinely hauled my touring bike down to a stop when I would spot a photo opportunity I didnt want to miss.
#12
afraid of whales
Properly adjusted BB7 work very well. I have road and MTB set-ups and both work just fine. There's no need for compressionless housing, that takes all the feel/progressiveness away. In the last 7 years I've never had to clean my rotors, just run 'em and enjoy the consistency and sureness. Once the pads get thin, slap in a new set.
Here's a great video that explains it very well. The most important point is getting the inner pad as close to the disc without rubbing, then set the outer pad to preference. Once BB7 are set up correctly all it takes is occasional adjustments of the pads for wear just like rim brakes. When I ride lift assist in Vail I adjust them at lunch. On my road bike after 2000 miles they're still untouched.
When I worked at an LBS none of the other mechanics knew how to adjust BB7s. Most new bikes all come with hydros, bleeding brakes is much more common than setting up BB7s.
Here's a great video that explains it very well. The most important point is getting the inner pad as close to the disc without rubbing, then set the outer pad to preference. Once BB7 are set up correctly all it takes is occasional adjustments of the pads for wear just like rim brakes. When I ride lift assist in Vail I adjust them at lunch. On my road bike after 2000 miles they're still untouched.
When I worked at an LBS none of the other mechanics knew how to adjust BB7s. Most new bikes all come with hydros, bleeding brakes is much more common than setting up BB7s.
#13
Senior Member
Thread Starter
Properly adjusted BB7 work very well. I have road and MTB set-ups and both work just fine. There's no need for compressionless housing, that takes all the feel/progressiveness away. In the last 7 years I've never had to clean my rotors, just run 'em and enjoy the consistency and sureness. Once the pads get thin, slap in a new set.
Here's a great video that explains it very well. The most important point is getting the inner pad as close to the disc without rubbing, then set the outer pad to preference. Once BB7 are set up correctly all it takes is occasional adjustments of the pads for wear just like rim brakes. When I ride lift assist in Vail I adjust them at lunch. On my road bike after 2000 miles they're still untouched.
https://www.youtube.com/watch?v=NasGJFtgq0A
When I worked at an LBS none of the other mechanics knew how to adjust BB7s. Most new bikes all come with hydros, bleeding brakes is much more common than setting up BB7s.
Here's a great video that explains it very well. The most important point is getting the inner pad as close to the disc without rubbing, then set the outer pad to preference. Once BB7 are set up correctly all it takes is occasional adjustments of the pads for wear just like rim brakes. When I ride lift assist in Vail I adjust them at lunch. On my road bike after 2000 miles they're still untouched.
https://www.youtube.com/watch?v=NasGJFtgq0A
When I worked at an LBS none of the other mechanics knew how to adjust BB7s. Most new bikes all come with hydros, bleeding brakes is much more common than setting up BB7s.
#14
Senior Member
jrick, I will bring this up just out of thoroughness, if you are aware, ignore. Don't forget that for a good hard stop, one should be using the front/rear brake force ratio at something like 70% front 30% rear. In a hard stop, its the front that does nearly all the stopping. When we stomp on the brake pedal in our cars, they are set up automatically with this range of brake balance.
when we brake in a car, or a motorcycle, or a bicycle, the weight transfers forward during the slowing down, with the majority of weight on the front, and so we need to haul more on the front brake. If you are not doing this, you will not get the proper braking that your brakes can do, and you will be overtaxing the rear brake and you wont be slowing down enough compared to predominantly using the front brake.
when we brake in a car, or a motorcycle, or a bicycle, the weight transfers forward during the slowing down, with the majority of weight on the front, and so we need to haul more on the front brake. If you are not doing this, you will not get the proper braking that your brakes can do, and you will be overtaxing the rear brake and you wont be slowing down enough compared to predominantly using the front brake.
#15
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The Avid BB7 is a bit touchy about setup as well. This article describes the setup nicely. I've used this technique on the BB7 as well as other, cheaper brakes and it have improved them greatly.
You don't say if you use them but I've also found that interrupter levers can degrade the performance of road bike levers with regard to disc brakes as well. The interrupters work very well but they build in some flexibility to the system that degrades the performance of the other levers.
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Solo Without Pie. The search for pie in the Midwest.
Picking the Scablands. Washington and Oregon, 2005. Pie and spiders on the Columbia River!
#16
Senior Member
Thread Starter
There's your problem. Mechanical discs simply don't work that well if you set them up like many people set up rim brakes. In other words, you can't set them up so that the brake engages at half lever travel. If you do, the brake feels mushy and ineffective. Simply shortening the cable won't help either. You need to set the pads up so that they are a minimal distance from the rotor when the brake is open.
The Avid BB7 is a bit touchy about setup as well. This article describes the setup nicely. I've used this technique on the BB7 as well as other, cheaper brakes and it have improved them greatly.
You don't say if you use them but I've also found that interrupter levers can degrade the performance of road bike levers with regard to disc brakes as well. The interrupters work very well but they build in some flexibility to the system that degrades the performance of the other levers.
The Avid BB7 is a bit touchy about setup as well. This article describes the setup nicely. I've used this technique on the BB7 as well as other, cheaper brakes and it have improved them greatly.
You don't say if you use them but I've also found that interrupter levers can degrade the performance of road bike levers with regard to disc brakes as well. The interrupters work very well but they build in some flexibility to the system that degrades the performance of the other levers.
Thanks
#17
Senior Member
Thread Starter
jrick, I will bring this up just out of thoroughness, if you are aware, ignore. Don't forget that for a good hard stop, one should be using the front/rear brake force ratio at something like 70% front 30% rear. In a hard stop, its the front that does nearly all the stopping. When we stomp on the brake pedal in our cars, they are set up automatically with this range of brake balance.
when we brake in a car, or a motorcycle, or a bicycle, the weight transfers forward during the slowing down, with the majority of weight on the front, and so we need to haul more on the front brake. If you are not doing this, you will not get the proper braking that your brakes can do, and you will be overtaxing the rear brake and you wont be slowing down enough compared to predominantly using the front brake.
when we brake in a car, or a motorcycle, or a bicycle, the weight transfers forward during the slowing down, with the majority of weight on the front, and so we need to haul more on the front brake. If you are not doing this, you will not get the proper braking that your brakes can do, and you will be overtaxing the rear brake and you wont be slowing down enough compared to predominantly using the front brake.
Thanks for raising this though.
#19
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As others have sufficiently covered, properly adjusted BB7's should work well for you. If you're interested in hydraulics, I would suggest checking out the TRP Hylex RS brakes. You can get a pair for under $250 and their performance is excellent.
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#20
Senior Member
I would also mention that definitely I had to learn a whole new bunch of stuff playing around with my BB7s, my first bike with discs, and have made numerous mistakes along the way. Its like any new skillset we have to learn, it can be frustrating and I often think that I have a higher than usual ability to do stupid stuff along the way, but usually muddle my way along, and getting better with BB7's did work out in the end.
I would say the main thing to be aware of is how small small clearance differences, either with pad to rotor distance, or caliper alignment, make a real diff in things not working well.
I also always need to have reading glasses on, and it can be handy to have a flashlight with you, and or a white sheet or paper to place on the ground to help see rotor alignment, pad to rotor distances etc.
I would say the main thing to be aware of is how small small clearance differences, either with pad to rotor distance, or caliper alignment, make a real diff in things not working well.
I also always need to have reading glasses on, and it can be handy to have a flashlight with you, and or a white sheet or paper to place on the ground to help see rotor alignment, pad to rotor distances etc.
#21
Senior Member
Thread Starter
I would also mention that definitely I had to learn a whole new bunch of stuff playing around with my BB7s, my first bike with discs, and have made numerous mistakes along the way. Its like any new skillset we have to learn, it can be frustrating and I often think that I have a higher than usual ability to do stupid stuff along the way, but usually muddle my way along, and getting better with BB7's did work out in the end.
I would say the main thing to be aware of is how small small clearance differences, either with pad to rotor distance, or caliper alignment, make a real diff in things not working well.
I also always need to have reading glasses on, and it can be handy to have a flashlight with you, and or a white sheet or paper to place on the ground to help see rotor alignment, pad to rotor distances etc.
I would say the main thing to be aware of is how small small clearance differences, either with pad to rotor distance, or caliper alignment, make a real diff in things not working well.
I also always need to have reading glasses on, and it can be handy to have a flashlight with you, and or a white sheet or paper to place on the ground to help see rotor alignment, pad to rotor distances etc.
#23
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Definitely. Some have a U-shaped arm the cable attaches to that actuates both pads. The model I'm thinking of (can't remember the brand) also has adjustment of each pad via 3mm allen key. IMO these offer performance which is almost as good as hydraulic, without all the bother and unreliability - cables don't leak.