XCSKIBUM

I'm looking to upgrade from Tektro Aquila mechanical disc brakes on my KHS XC904r frame build bike. The mechanical disc brakes work great, but I want to use them to convert from the rim brakes on my Crosstrail Sport Hybrid. Since I'm going to be buying a new brake system anyway, I would like to upgrade to juice brakes on the KHS MTB.

This is NOT a downhill bike so I don't need the latest greatest high performance hydraulic brakes. A good reliable 160mm setup is all I'm looking for.

I'm looking for the most "bang for the buck" in reliable, easy to maintain performance for riding on moderate terrain. I will not be riding down anything I can't ride, or push, the bike up, so brake fade on long descents isn't an issue.

Please don't specify expensive high end set-ups that are more that what I need.. I'm on a limited budget and something with perhaps a little better modulation than the Aquilas is all I need.

gsa103

Shimano Deore. There's also cheaper versions that are perfectly good, but I prefer the Deore lever shape.

Dan Burkhart 

+1. Couple that with the fact that Shimano hydraulic is simple and straight forward to fill and bleed when compared to some of the others, it would be my preference.

well biked

+ another for Shimano Deore. Shimano hydraulics rock. The 4xx series Shimano hydraulics are perfectly fine, too, and cost less than Deore.

XCSKIBUM

That's the sort of thing I'm looking for, ease of maintenance.

I found this .

Looks like it would bolt right up to my current 160mm mounts.

HillRider

A question. Does the Crosstrail you are planning to transfer the existing mechanical disc brakes to have fork and frame mounts for the calipers and are the wheels disc capable?

XCSKIBUM

Yes, although the rear will be a bit tight, and cable routing will be tricky, the mount points are there. The fork lower leg will be pretty straight forward.

HillRider

Good, you thought this through. We get a lot of questions from posters who want to add disc brakes to a frame/fork/wheelset only equipped for rim brakes so I wanted to be sure this wasn't the case.

gsa103

Same item, just cheaper. Discs not included but you should be able to re-use the Tektro ones.

Shimano Deore BR-M615 M610 Hydraulic Disc Brake Set M596 Upgrade Left & Right | eBay

XCSKIBUM

I've been "thinking it trough" for some time. Shortly after I bought the bike in August of 2010, I was having multiple spoke failures on the rear after I dropped off the edge of some pavement. (I'm a lard ass you see.) The LBS where I bought it covered a new wheel under warranty. I paid a few $$$ extra to get a DT Swiss dual purpose rear wheel that had a 6 bolt disc hub and much better quality than the OEM wheel. For the front I will just get a 6 bolt hub and lace up a new wheel. The OEM wheel has seen some rough use on XC ski/snowmobile trails & such.

We ride a lot on abandoned RR beds and when it gets sloppy the old pulverized coal cinders really grind away when you 1st put on the rim brakes. It almost as bad as squeaking chalk on a black board. In truth, that's the main reason I want discs. Mechanicals would do and at one time that was what I was planning on doing, but I want to get my feet wet with juice brakes in case I have some come into the shop.

XCSKIBUM

The discs will go along with the mechanical brakes when I convert the Crosstrail.

It still might be cheaper to get those & buy the discs separate. I put them on my "watch list" and will check out the price of discs.

XCSKIBUM

It looks to me like some of these are sold as a sealed system. I'm not one to tolerate wrapping hoses that are too long around stuff to avoid cutting them to length.

I have almost 50 years experience with hydraulic brakes on cars, truck & motorcycles. What is involved with cutting the lines to the proper length and bleeding the system?

I am aware that some take different brake fluid than others.

gsa103

If you have a larger frame size 29er, chances are you won't need to cut anything. They're generally sized to fit XL 29er frames, so if you're reasonably close to that it may not be worth the effort.

Remove the insert nipple and olive, re-install into the new short length and connect back together. Theoretically, you're not supposed to re-use the olives (compression fitting), but most people don't have issues with re-using once or twice. The entire process should take all of about an hour including screwing up twice and needing to bleed. If you're good, it's a 10 min job.

If you're careful, you can do it without even needing to bleed. Watch a few videos on YouTube, you'll get the idea quickly.

Also, if you're getting Shimano brakes, get Shimano rotors. Avid pads have a slightly different shape and they aren't completely compatible.

Also, buy the Shimano bleed kit with the funnel, it makes everything really simple.

HerrKaLeun

If you want to be cheap, why not install hydro brake on both bikes on front and use the mechanical brakes in rear of both bikes? The front brake is the primary brake, so the rear mainly is only used in low-grip situation. Maybe the different feel between front and rear would be annoying, but you could try.

I'm converting my mech. discs to Deore. Haven't completed yet, but in a mockup just the easier adjustment of caliper was impressive. Your mech brakes likely only have one caliper and "bend" the rotor to the non-moving opposing brake pad. I always had some friction noise i couldn't get rid of. Now with the 2-piston brakes that noise is just gone. You won't regret going hydraulic.

If you can afford it, make them all hydraulic. Once one of your bikes has hydraulic brakes, do you really want to ride the one with mech. brakes?
This is my personal opinion (of course): either use hydraulic disc brake or cable linear pull. Mechanical disc brakes are just a marketing thing to claim the "car like disc brakes"

Ronsonic 

I'm not affiliated with these guys other than as a customer. I have a pair of Shimano SLX M675 in the Royal post right now. They are seriously on sale.

I'm upgrading from Auriga. Check what kind of mounting adapters you might need - easy to find part from Shimano.

XCSKIBUM

[QUOTE=gsa103;19485052]If you have a larger frame size 29er, chances are you won't need to cut anything. They're generally sized to fit XL 29er frames, so if you're reasonably close to that it may not be worth the effort.[/QOUTE]
Unfortunately the bike in question is a small frame 26" XC Bike so cutting the lines will probably be necessary.

Thanks for the tip. I'l get the kit.


When you ride through puddles on a RR bed that last saw extensive use by steam locomotives before it was abandoned, just about any disc brakes, mechanical or otherwise, are a vast improvement over rim brakes.

HerrKaLeun

I think in times of $32 Shimano hydraulic brakes there is no justification for mechanical brakes anymore. Once you have the disc wheels etc. just go all the way.

HillRider

Hydraulic discs require more then just the $32 calipers. You need brake levers or brifters with hydraulic master cylinders and those run the cost of conversion way up. Mechanical discs can be used with your existing brake levers or brifters.

XCSKIBUM

With the caliper/MV/hose kit amd a bleed kit, it is going to cost me $125 even if I use the existing rotors.

My AVID BB7 and Tektro Aquila mechanical disc brakes work just fine for what I ride. If it ain't broke, ya can't fix it.

If it wasn't for the fine coal cinders (think tiny shards of glass) grinding my rims away, the rim brakes would suit me just fine too.

HerrKaLeun

complete Shimano Acera brake for $32. This one has dual piston and has the easy maintenance of shimano

this complete brake set with disc for $26 is probably not great

Front and rear shimano 315 for $55

They really are not that expensive anymore. Some mechanical brakes cost that much. It is OK re-using already paid for mechanical brakes. But if you buy new brakes there really is no excuse.

XCSKIBUM

Where did I say that I was going to buy new mechanical disc brakes?

As far as "easy maintenance of Shimano? I've been researching that and I don't see where the Sram bleed technique is so complicated. Yes, it does require 2 syringes, but it seems to be a lot less "fiddly" than the Shimano technique. Add he fact that Sram uses DOT brake fluid that I can buy anywhere and the Sram Level T system is starting to look good to me.

HerrKaLeun

I didn't say you were to buy new mech brakes, I meant it in general.

I haven't researched if mineral oil or DOT fluid is better. But DOT fluid is hygroscopic and once you open a bottle you need to use it up within less than a year. For mineral oil you can buy a gallon and keep forever. DOT 3/4 also brings water in your brake system along with corrosion. Maybe this is not a big problem, and the mineral oil also is supposed to be replaced at some point. And you can't put DOT 5 in DOT3/4 brakes. I'm not arguing for the one or the other, just consider what either fluid type will require.

gsa103

Mineral oil vs DOT 5.1 is an old debate.
Mineral oil is essentially non-toxic and doesn't expire, but is significantly more expensive.
DOT 5.1 is cheap in bulk, but requires annual bleeding, is toxic and eats paint.

For a bike that is ridden hard frequently, DOT fluid is probably better because you're going to need to bleed annually. With bikes that may only get ridden less than 40 times a year, mineral oil can last several years without bleeding.

XCSKIBUM

Just curious as to why DOT brake fluid can be left in cars and motorcycles for decades yet in a bicycle it needs to be flushed annually.

Is it because of the smaller volume of the systems?

HerrKaLeun

You have to replace brake fluids in cars every 2-3 years. You can leave it in for decades.....as long as you never have to brake hard
The water lowers the boiling point, creates steam bubbles, which takes away you braking power because then the brake is not hydraulic anymore. The water also will cause corrosion, weakening and dirtying up your brake system. You won't notice under normal operation, but in an emergency the pressure will burst the brake line (the weakest part will brake) and you lose brake pressure.

A brake system is not the part to neglect maintenance. I don't know how the temperatures compare to bicycles, but sure the small water corrosion and dirt parts are not good for bicycle brakes either. I assume everything being smaller in a bicycle makes a small dirt particle more dangerous than in the large car brake parts. A car brake system is also a highly regulated system, bike brakes are simple and cheap.