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Discussion Starter · #1 ·
I am new to mountain biking and got an 09 Kona One20 Primo which came with some Shimano M575 Hydraulic Disc Brakes.

After riding for a couple months and I am going downhill faster, I really starting to notice that the brakes are weak. I had my shop tested them and they said they are working fine. I did a search on them and found a not so great review on them, makes me think maybe I should look into upgrading.
http://www.bikeradar.com/gear/catego...-pair-09-34502

If I was to upgrade the brakes, can I just upgrade the caliper and keep the same rotors, hoses and levers? or is that a bad idea? I assume I will have to have a shop to bleed it.

Should I upgrade both front and rear?

There are so many lines of Shimano Brakes, what's a reasonable upgrade (under $300)?
 

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1. The cheapest, easiest way to get more powerful brakes is to go up one rotor size front and rear. You probably have 6" rotors so you can get 7" rotors and new caliper mounting adapters starting at only $40! This will make a noticeable difference in initial power and fade resistance. It will also add a little weight.

2. All Shimano brake levers and calipers are compatible so you could just upgrade one or the other to SLX or XT but I don't know which (your levers or calipers) are the weak link.

3. Or you could buy a complete Avid Elixir R setup for about $200.

My vote is for option 1 or money being no object, option 3. Even SLX, XT, and XTR aren't exceptionally powerful brakes.
 

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Discussion Starter · #3 ·
Lelandjt said:
1. The cheapest, easiest way to get more powerful brakes is to go up one rotor size front and rear. You probably have 6" rotors so you can get 7" rotors and new caliper mounting adapters starting at only $40! This will make a noticeable difference in initial power and fade resistance. It will also add a little weight.

2. All Shimano brake levers and calipers are compatible so you could just upgrade one or the other to SLX or XT but I don't know which (your levers or calipers) are the weak link.

3. Or you could buy a complete Avid Elixir R setup for about $200.

My vote is for option 1.
Hi Lelandjt, thank you for your quick respond.

If I go with 1, will I need some kind of adapters to move the calipers further out? Any particular brand you would recommend? Would you recommend trying to bleed it anyway?

Those Avid Elixir R have great reviews, will you take them over Shimano XT? Is 5.1 fluid a bad idea compare to mineral oil?

Thanks again!
Cars
 

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carsonau said:
Hi Lelandjt, thank you for your quick respond.

If I go with 1, will I need some kind of adapters to move the calipers further out? Any particular brand you would recommend? Would you recommend trying to bleed it anyway?

Those Avid Elixir R have great reviews, will you take them over Shimano XT? Is 5.1 fluid a bad idea compare to mineral oil?

Thanks again!
Cars
Well, first off.......don't base your judgement on just one review. Read a few dozen. Many times, a fix is posted in the review itself, if the writer found it. For the most part, they're fine for XC and light downhill use, depending on what you mean by "downhill fast" you may just be pushing them too hard.

A good bleed might help. Shimano's factory bleed isn't exactly stellar, so pick on your shop wrench to do a proper job of it.

Larger rotors, yeah. I would just go larger in the front, though. Going downhill, most of the braking power is in the front, and too much brake in the rear with the back end unweighted will cause skidding. Not only does that cause some lack of control, it's bad for the trail. Yes, you will need an adapter, the caliper will need to be mounted out further to accomodate the larger rotor. Try to get a round rotor, like one from Hope. I don't mind wavy rotors, but you lose contact area. Even just switching to the same size rotor using a round brake path can make a difference. You're probably limited to a centerlock rotor, though, so get what you can that fits.

Avid over XT.......I'm still up in the air about that one. I like the Avid design, and they seem fine for general use, but I think you'd have the same issue as you do now. They're an XC brake, not designed for downhilling. XT's would be the better choice, if you want to go that route. Still an XC brake, but more power. Lots of modulation though, and some people don't like that. Mostly guys coming off Hayes with their on-off feel. Actually, that's one place you might want to look. Hayes Strokers seem to be pretty good, and might fit your needs better than either the Elixrs or XT's. They're the ones who pretty much wrote the book on downhill brakes. Not too expensive, either, I saw them the other day for $100 per wheel, you just need to buy the adapters for your fork and frame. Again, the centerlock rotor thing. You won't be able to use aftermarket rotors, unless they specifically make one for your hubs. Not a big deal, for the most part rotors are interchageable. As long as the diameter matches what your brakes take, you're fine.

DOT vs mineral oil. Age old debate. What it comes down to is DOT has a higher boiling point, so theoretically less fade as the brakes get hot. Downside is it's caustic, harmful to the environment (big deal for me, since I do biking advocacy. Nothing will shut down a trail faster than a puddle of poisonous fluid spotted by the forestry guy you're walking the trail with). Mineral oil boils at a lower point, so theoretically fades faster, but the Magura Gustav was one of the top downhill brakes, and it used mineral oil. Take that with a grain of salt. It's also safer to work with, safe for the environment, and in a pinch, you can use unscented, chemical free baby oil as an emergency backup. I wouldn't suggest leaving it in there, get the proper stuff as soon as you can.
 

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Discussion Starter · #5 ·
Thank you for your very helpful respond, I think I will start out with a larger front rotor and a brake bleed (either learn to do myself or get a shop) and go from there. Is after-market brake pads worth considering?

I mostly do XC ride and the brakes are good enough 95% of the time, there is just one hill I go down daily that has a very long and steep downhill, and unless I keep the braking on all the way, I don't have a chance to stop at the bottom.
 

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carsonau said:
Thank you for your very helpful respond, I think I will start out with a larger front rotor and a brake bleed (either learn to do myself or get a shop) and go from there. Is after-market brake pads worth considering?

I mostly do XC ride and the brakes are good enough 95% of the time, there is just one hill I go down daily that has a very long and steep downhill, and unless I keep the braking on all the way, I don't have a chance to stop at the bottom.
EBC makes good pads, but I think you're on metallic pads right now anyway. Switching to organic may help, particularly in wetter weather. Wouldn't hurt to try, if you felt like it. I think you're fine on what you have now.

Try this. Take the pads out, and give them a light sand if they look shiny. Don't go crazy, just use a fine grit sandpaper and lightly sand off that glaze. That'll give you a bit more power. Do NOT squeeze the lever with the pads and wheel out, or you'll be here asking how to get the pistons apart and back into the bores. Put something in there to help prevent that from happening, or stick a tennis ball between the lever and bars, just in case.
 

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It hadn't occurred to me till now but maybe these lower end Shimano brakes come with organic pads. They are less grippy and powerful feeling than the metallic pads that came with my XT and XTR so a swap will help. Take'em out and see what the backplate says.
I recommend going with the same size rotors front and rear. Otherwise it makes your rear brake feel weak and I like a good rear brake.
I've never tried Elixirs but have heard that they have a lot of power for an XC brake and are great for DH. I'm not impressed with the power of my XTs.
For adapters and rotors there's not much difference between brands and models besides slight differences in weight. The lightest rotors have less surface area so they're less powerful feeling. I just google shopped and found 7" rotors for $15 and adapters for $5.
 

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Discussion Starter · #8 ·

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carsonau said:
Would this be the Adaptor I need to go from 6" to 8" rotors, or something similar?
Only if you have 6" post mounts on your fork and want to run 8" rotors. 7" rotors will be plenty for all but full-on DH riding.
Assuming you have 6" post mounts on the fork and IS tabs on the rear these are the adapters and rotors you'd need.
7" Rotors: http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=140370239038&rvr_id=&crlp=1_263602_263622&UA=WVS%3F&GUID=3838cf441220a043a8c33273ffd26d5c&itemid=140370239038&ff4=263602_263622#ht_738wt_939
Front adapter: http://www.bikeman.com/BTI-MU8670.html?utm_source=GoogleBase&utm_medium=GoogleBase&utm_campaign=GoogleBase
Rear adapter: http://www.ebikestop.com/tektro_rr_180mm_adaptor-BR7345.php
These are just the cheapest examples I found on Google Shopping.

You might as well get a bleed kit and learn how to do it. If you're gonna be MTBing for years you'll save a lot of money and always have perfect brakes.
 

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Lelandjt said:
Only if you have 6" post mounts on your fork and want to run 8" rotors. 7" rotors will be plenty for all but full-on DH riding.
Assuming you have 6" post mounts on the fork and IS tabs on the rear these are the adapters and rotors you'd need.
7" Rotors: http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=140370239038&rvr_id=&crlp=1_263602_263622&UA=WVS%3F&GUID=3838cf441220a043a8c33273ffd26d5c&itemid=140370239038&ff4=263602_263622#ht_738wt_939
Front adapter: http://www.bikeman.com/BTI-MU8670.html?utm_source=GoogleBase&utm_medium=GoogleBase&utm_campaign=GoogleBase
Rear adapter: http://www.ebikestop.com/tektro_rr_180mm_adaptor-BR7345.php
These are just the cheapest examples I found on Google Shopping.

You might as well get a bleed kit and learn how to do it. If you're gonna be MTBing for years you'll save a lot of money and always have perfect brakes.
He's got IS tabs front and rear.
 

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Discussion Starter · #13 ·
savagemann said:
How much do you weigh?
That will help us help you alot better.
170lbs, 90% of the time these brakes are good enough, there is only 1 long & steep trail when I bike home from work that the brakes become useless when I get close to the bottom, to a point it is very dangerous.
 

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That's called fade and is caused by heat. The larger rotors and a fresh bleed will help manage heat and eliminate water in the oil that is vaporizing.
 

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Discussion Starter · #15 ·
Lelandjt said:
Okay, so use this front adapter: http://www.ebikestop.com/tektro_frt_180mm_adaptor-BR7344.php

Now you're looking at $38 + shipping for rotors and adapters. That's pretty cheap for a big boost in power. I'd do this first and then replace the pads with metallics if they are organic and not grabby enough for you.
I really appreciate your help with finding the right adapter.

I found a really cheap Alligator 7" Round Rotor at Pricepoint, should I be concern about its quality?
http://www.pricepoint.com/detail.htm?stylePkey=15797&style_id=115 ALIRR6
 

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That should be fine. I use Alligator's Serration ultra-light rotors on my XC and DH race wheels. They are lighter but have less surface area so they're not quite as powerful as the ones you're looking at.
 

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Discussion Starter · #17 ·
Thank you again for all those who contributed, nice to see an online mtb community with helpful and knowledgeable people. :thumbsup:

I end up finding a Shimano 180mm rotor for $16 from ebikestop, same place I am getting the brake adapter from so I can safe on shipping.
 
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