New to disc brakes... is this normal?
I got a bike with disc brakes on it. From what I've read, they're rather crappy disc brakes, as far as disc brakes go. That's ok with me as long as they 'work'. I wanted a bike already equipped with disc brakes so I had the option to upgrade to better ones down the line if I want (rather than trying to convert V-brake bike to disc brake bike).
Anyway, is this how they're supposed to work? When I apply constant pressure to the front brake, I can feel the brake grip, then release a bit, then grip, then release a bit, then grip... etc. There is friction the whole time but it definitely modulates in rhythmic sort of way... stronger grip, weaker, stronger, weaker, with no variation on the amount of pressure I'm putting on the brake lever.
Is this a problem with my brake? Or is this normal? I have no idea.
sounds like a warped/bent rotor to me
Honestly... ahh I give up
I agree, but just for fun, check the rotor mounting bolts and make sure they are tight.
Originally Posted by highdelll
Yeah, ^^^ this.
Originally Posted by highdelll
What rotor do you have? Some combinations of rotors/brakes can do that.
like this one.
The bike is brand-spanking new (brought it home yesterday) so you could be totally right about the warped/bent rotor but I sure hope not on a new bike.
The brakes are Tektro Novela Mechanical Disc, 160mm Rotors. They got pretty dismal reviews on Amazon but that's my only reference for how good/bad they are.
Thanks so much for you input! I really appreciate it. I'll call the shop about it or wait until the break-in tune-up.
It will take some time to bed in the rotors and pads. What I did on my cross bike was to ride around the block a few times with first one brake and then the other brake on part way. I put it in low gear and then pedaled along with enough brake pressure to control my speed. I could feel the heat in the calipers/rotors when I stopped. Really improved the braking force and smoothness, but that continued to improve over the next few rides. Plus you might try cleaning the rotors off with some isopropyl alcohol and a clean rag a few times.
depends on how well the rotor was packed when shipped, it might have come a little bent.
Great suggestions. Will give it a try.
Torx T25 to remove the bolts. Or an Allen mm size. They have blue Loctite which you can retighten. To check for flatness place it on a piece of glass and tap it around the edge, flip and repeat. If it rocks it's bent.
Brakes take time to break in...though Tektro has a bit of a bad rep.
As far as upgrading, take a look at Avid BB7's...mechanical (no need for new levers and tubing), and will out-perform a lot of hydros...and Bluesky cycling runs sales on them now and then for about $100 (discs and calipers). If you have the cash on hand, I'd buy them and not bother screwing around with your Tektro's.
On the other hand, if you want to wait, I'd spin the wheel and see if the rotor wobbles as it rotates...if not, then it's most likely that they just need some time to wear the protective coating off of the pads.
Another beginner question, is there really a big difference between mechanical disk breaks and hydraulic ones? Why are hydraulic one's so much more $$?
Your bike has ABS
1st off :
Originally Posted by FriarTuk
BrakesBrakesBrakesBrakesBrakesBrakesBrakesBrakesBr akesBrakesBrakesBrakesBrakesBrakesBrakesBrakesBrak esBrakesBrakesBrakesBrakesBrakesBrakesBrakesBrakes BrakesBrakesBrakesBrakesBrakesBrakesBrakesBrakesBr akesBrakesBrakesBrakesBrakesBrakes!!!!!!!!!!!!!!!! !
2nd) the upper-end hydraulic BRAKES () are much nicer with modulation and power than any mechanical out there.
The reason why the cost is higher, in mid to lower levels is a bit of a mystery to me - but I think it has to do with more parts/pieces and assembly - and also some to do with marketing/consumer beliefs (hydros are super cool and mechanicals are so lame)
The top of the line mechanicals (Avid BB7s paired with a lever like SD-7) are on par with mid-level hydros as far as performance., yet seem to be almost half the cost (last time I looked)
Some say hydros are more set-it-and-forget-it, which is largely true.
Others like the reliability/FIXABILITY of a good mechanical when especially deep into the trail.
Most just ride what got (not necessarily here on MTBR!)
Honestly... ahh I give up
Yes and no:
Originally Posted by FriarTuk
They both perform the same task: stopping you and your bike.
I have BB7's, and they are the best mechanical disc calipers out there...just is what it is. I have not used hydros for more than a few rides, so this is mostly just info that I have learned from hours of research over the years, haha
Mechanical is cheaper because of the system...a steel cable, a spring-loaded caliper, and a lever. That's pretty much it (for simplicity's sake). BB7's are good because they are very good mechanical brakes...easy to adjust, easy to care for, no bleeding, and, when under braking loads, they don't fade the same way hydros do (which require feathering during long breaking periods to re-prime the caliper pistons).
They also out-perform a lot of hydros because many hydros are not designed well: they get hot fast, flex, don't hold pressure well etc.
Now for hydros:
They have smaller calipers (lighter, though the brake fluid must add more weight, so I'm not sure if they come out ahead or not), are arguably more "precise" and take less pressure, therefore less energy, to achieve the same stopping power. High end hydro calipers also have multiple pistons, and move both brake pads towards the disc, instead of pressing one against the disc, and flexing the disc into contact with the other (as is done on mechanical calipers).
They also have more hardware: the levers are also pumps, with reservoirs for extra brake fluid. The lines are full of the stuff, and if you sever a line, you don't have brakes anymore (though this does not happen often). Many people don't like the idea of replacing fluid, or bleeding the lines every so often.
They are more maintenance in general...I have heard of people getting grit in them, and having to replace a lot of the hardware.
EDIT: more maintenance in that the time it takes to fix them is more than that of a mechanical system...not overall amount of time spent on them. Mechanical brakes do require cable adjustments here and there, dep. on use
Hydros cost more because of the parts involved. They are more complex, and complexity increases cost.
Hydros help with "modulation"...though BB7's seem to handle this pretty well, too
All of this is just general info...I like BB7's, but if I had the cash, I'd buy into some nice Avid hydros.
I have cheap Tektro I/Os on my Hardrock and I love them compared to v-brakes, they have awesome reliable stopping power and that makes me *very* happy on the trails.
Originally Posted by Dundee85
That shutter may be from the rotor design as it as it rotates through the caliper. In some areas there may be more surface area for the pads to grip and that's what u might be feeling. I know this from the front rotor I currently have installed, the extra surface area on those is where the arms reach the rotor ring.
I'm not saying that is exactly what is going on in your situation, but if u examine it maybe you will find that.
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My 10 year old Magura Julie hydro discs have required less maintenance than the BB7's I installed on my commuter last fall.
A decent set of hydros will always be better than mechs, IMO. more expensive, too. that "decent" pricepoint has been coming down a bit over time, and so has the "good" pricepoint. Top end pricepoints always seem to be climbing, but that tech tends to trickle down over the years. There have been a number of low end hydros on the market over the years. These are not worth it. Better to have a respectable mech disc brake.
BB7's have been the best mech discs for many years. The movement in that segment has been at the low end for the most part. So there are more "meh" mechanical disc brakes on the market. Some of them are actually worse than decent vees. Most are about equivalent.
I know this is a little bit off topic but what do you guys think about this deal?
New Avid BB7 Disc Brake Calipers+G3 rotors Front&Rear | eBay
Compared to the price on chainreactioncycles.com these are like half of the price so I really don't know what to think... It's something that seems great deal, based on the fact I live in Bosnia and I don't have much options, either things are too expensive to buy in the shop or if I find a deal on the internet the postage gets as high as item I would like to buy... and that's IF they do shipping to Bosnia.
Should I pull the trigger?
What we do in life, echoes in eternity...
Lots of good info, Dundee, but let me add a few suggetions.
First, make sure you understand proper setup and maintenance.
Tektro User Manual
Second, if your *new* discs were somehow bent (which I feel is unlikely), then simply straighten them out. You can gently press or pull the disc to get it fairly straight. If your pads are set with appropriate clearance (see manual) then you'll see where they're warped as you spin the wheel and watch the disc pass through the calipers. USE A LATEX GLOVES when touching the discs to avoid greasy finger smudges.
Third, make sure you bed in your brake pads. The brakes aren't fully operational until you transfer pad material to the disc surface. As suggested, go around the block and do 8-10 HARD stops until you generate enough heat to transfer pad material. Pic below shows what they'll look like if done right.
Fourth, do not clean the discs with isopropyl unless they've been contaminated with a slippery substance, i.e. chain oil, lube, greasy fingers. The pad material on the disc surface is what gives it grip, so leave that intact. If you need to clean the discs, you'll need to bed in the pads all over again to regain effectiveness.
Finally, don't put too much stock in what others have written about your brake system. Some may have very little knowledge about brakes and what it takes to make them work properly. As one poster commented above, the Tektro I/O's are great when properly dialied in, even though they get poor reviews. I've had those brakes and couldn't agree more. But you need to read the manual, set them up correctly and then bed them in.
These are not terribly complex systems and, with appropriate attention, will work as well as anything out there, i.e lock up with minimal effort.