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How blue is your disc ?
Hi all, picked my new second hand Specialised Epic, like wow, specially after stepping off an Orbea hardtail which served my purpose well. Anyway, went for a ride, Woodford to Glenbrook, during the descent my rear brake started making painful noises, didn't notice beforehand it now appears that my disc/rotor has blued, it's certainly a different colour to the front disc, checked pads, plenty of meat left, disc runs true. So how blue can they go before replacing, I assume softer pads would be available ? Any advice is good advice.
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Don't sweat it, as long as it's still true you're fine. The blue is simply because you've overheated it but does no structural damage to stainless. If you regularly overheat the disk you run the risk of warping it, its common on motorbikes but I've not seen in on MTB.
Don't pedal and brake at the same time
You must have been pushing it pretty hard on the Oaks. Was this after the helipad?
I would suggest altering your braking technique, you must have had massive brake fade!
Instead of constantly dragging the brakes with a small amount of pressure, try braking a bit harder but for short periods. I'm not saying lock the brakes then release, just a bit firmer than you currently are and then release for a couple of seconds.
If you're already doing this, maybe a better quality pad or rotor is in order. Even a larger diameter rotor would help.
Certainly not braking and pedalling at the same time, big discrepency in efficiency there Chopstir, the noise started before helipad.
Brakes did fade Pete B, I'll have to try that brake method on a not so steep hill first, may take some mastering. You have me thinking about rotor diameter, wont the positioning of the caliper determine rotor diameter ?
Yes, it does. Just use these adaptors to suit whatever size rotor you want.
http://www.wiggle.co.uk/shimano-disc-brake-calli...
Just in case you took me seriously about the braking & pedaling at the same time, I was only being silly.
If you raise your rotor size you will also need a spacer to raise the caliper.
You said your rear changed colour but not the front, are you using your front? It does sound like your relying on the rear more. You should be using your front brake slightly more than the rear as far as pressure and overall use goes. The only times this doesn't apply is descending a very very steep loose hill or dropping down technical sections.
You will get more stopping power by applying the front brake more than the rear.
You will not go over the bars if you shift your weight back when applying a heavy brake to stop quickly.
Bigger rotor will help with heat dispersion but kind of over kill on the oaks.
Go with the technique change. Dragging the brake is bad, M'Kay
You know Chopstir just as I clicked save on my reply I thought what if he was ....... and then it was to late.
I'll have to change my braking technique, body stance, etc, I have dreadful thoughts of the front wheel slipping out from under me under hard braking.
I see what you mean PeteB with the spacer for the caliper, great idea but, I just got the purchase of the bike passed from minister of finance and now I have to modify it .... you know where I'm going.
Thank you everyone, much appreciated.
You'll gain a lot more from learning how to use your front brake properly.
160mm is fine for the Oaks ... unless you're running worn-out pads.
The trick to avoid going over the front is to push your butt behind and below the saddle. The trick to avoid washing out is never to brake with the bike leaning over; always do your braking in a straight line, before you arrive at the corner.
There are some trails in the Blue Mountains that will turn a 160mm rotor blue, but the Oaks ain't one of them.
Maybe a skills course sometime real soon might give you the requisite knowledge to become more confident, and avoid forming bad habits you'll then have to un-learn? Worth the money easily, in my experience.
I had an epiphany when I found I was managing to wear out front brake pads faster than the rears.
Learn to use it - you'll be amazed at how late and hard you can pull up without binning it.
looking up, elbows high and wide, butt back...
Also setting your levers properly helps too. It's a little personal preferance but I have mine about an inch or so in along the bars from the grip so 1 finger sits nicely in the bend at the end of the lever and then set the reach so it's pretty close to the bars. Just find it more control and less fatigue and arm pump/
Hawkeye is spot on with his info.
I recently raced a national downhill race in Bright. Its by far the steepest track I have ridden in Australia. Its a 4 minute run with no pedalling at all and your off the back of the bike the whole time.
Back in the pits walking around everyone's rear 8inch rotors were blue, even Sam Hill and Troy Brosnans! I am still using the rotor with no issues.
Agree with Flynny's comments on brake setup. Makes a big difference to ability to control the bike and forearm fatigue.
For me I find that to set up comfortably for 1 finger braking I need to set things up in the following order from grips in on the bars.
Grips, shifters and then brakes.
Most bikes are set up grips, brakes then shifters which for me means I need two fingers to get leverage. Moving the brakes inwards on the bars gives good leverage on your index finger only.
This works for me running SLX and X0.
Depends on how long your brake levers are and your hands.
Dragging your brake is always bad for heat. Same in a car although Aussie doesn't really have any big hills or mountain roads. Dragging brakes on some gravel kiwi roads back home, especially towing a boat is guaranteed death 100m over a cliff into a river. In 80's Falcons used to have to balance and judge brake sponginess/brake fluid temperature versus transmission fluid temperature from engine braking on long descents. Vaporizing either was very bad. Even 90's Subaru manuals with 4 wheel discs you had to be careful to not boil the brakes on long gravel descents. Steep gravel was always worst as you had to keep speeds right down otherwise the boat would shunt the back end of the car sideways in a corner towards the cliff.
It was always a continual trade off between building up speed to cool the brakes versus getting too fast.
Some NZ ski fields with gravel roads are also enough to boil brakes if you drag them without towing anything. Most of these roads have no safety barriers. You must use a low gear so the engine helps slow the car.
Some of the original ABS systems which wouldn't let a car lock up enough to dig through loose gravel were also interesting but that is even more off topic.
All great advice people, I think the most beneficial thing for me to do is get some proper tuition, learn from people more experienced than I, I'll get on interweb and search.
Thanks everyone.
forgot about the dipped heals, it hard remembering just what you do once it becomes second nature
http://youtu.be/PiQGFX_RlW4
Body position placement plays a major part in all forms of cycling and the principles are the same.
One place I learned a lot about body placement is from watching the MotoGP. A quick search and I found these clips to be very handy with a lot of good tips that really do apply to Mountain Biking as well!
http://youtu.be/znU_fyFZBRQ
Body Placement
http://youtu.be/yxWBKmfKndI
Really good clip about Body placement when cornering.
http://youtu.be/E6FCKKNqp0E
Some good tips about braking
http://youtu.be/oaxjSJnwE4A
MotoGP Race clip
Hell no mr Stir, sir/
Good body position on a road bike with rounded edge tyres and smooth grippy road is very different from good body position on a mountain bike with squarish tyres and loose changing surface. In fact it's almost completely opposite.
Moto GPs weight the inside foot and hang off the inside of the bike in the corners. Do that on dirt and you'll be wearing some.
On a MTB in a flat corner you keep the body relatively upright, weight the outside pedal and grip to force the corner knobs of your bike into the loose surface for better grip.
Totally different kettle of fish
http://youtu.be/J7dnXiNBDXE
Flynny is totally correct with the pedal weighting and braking technique.
corner more was all I got out of the motorbike learners course.
Pretty much everything else was all different. Especially bar pressure. Putting weight on the front wheel through the bars on a motorbike just jams the throttle on in a corner.
Nice posture on a mountain bike with strong core and straight back was also wrong apparently.
The only advantage mountain biking gave me was low speed. The Yamaha 250s at the riding school were so much easier to track stand! Nice and heavy with fat tyres. Everyone behind me had to stop behind me and a foot a foot down.
And also knowing how to counter steer (this is not drifting) with the bars to roll a bike over in a turn was similar. Ie flick bars left to initiate a turn right before letting the bars go to the right and vice versa.
When I'm flying down the oaks post helipad. I find shifting my weight to the front wheel and inside allows me to take the corners faster and I feel much safer taking the corners at higher speeds. If i stay more upright i find it more difficult to turn and find myself wanting to go straight as noted in the moto clips. I certainaly dont do this everywhere.
I always try to turn with outside foot pedal down unless pumping through a burm. This is different to the moto vids.
I found the idea of not slamming on the brakes but apply a small amount first to allow the surface contact area to expand before hard braking a useful tip.
I found the tip of keeping a straight line from elbows to finger tips to line your brakes and prevent premature arm pump useful. Of course this wouldnt be the same spot as a moto as your posture is not the same.
I found the braking posture interesting, and a case by case would apply to this.
I found the tip do not lock out your arms but keep your elbows slightly bent useful.
Ofcourse body position and posture are not the same. I think you would be pretty stupid to try and ride like a motor bike all the time. Personally i thought there was lot of good tips that did apply to Mountain biking and also showed an importance on how body positioning played an important role in cycling. I guess others didnt see the same as me.
No offense meant chopstir. just pointing out the difference, I'm not a complete slouch on the trails and just pointing out what I've learn from experience, watching and talking to the elites and training (For what it is worth I don't ride the oaks that much but last time I raced the classic I went sub 47mins and VTSS350 is the 2013 over 30s state DH champion of the universe.... or something)
"If i stay more upright i find it more difficult to turn and find myself wanting to go straight."
The tip is to lean the bike but stay above it so your weight is pushing perpendicular to the ground, not along it. Your outside foot is down and back a bit with the knee twisted in, almost leaning on the frame. Outside elbow high and forward with your head looking around the corner (you go where you look)
I probably won't ever be in the same league as Flynny etc but think I know what you mean as I started off like that. If we are talking about the same thing.
At speed with your body high the bike does want to go straight ahead. At speed the wheels gyro stabilise big time.
At low speed you can turn left by turning the bars left.
At speed trying to turn left by turning the bars left really doesn't work and the bike resists. To overcome this I used to get my weight forward and into the inside of the turn.
What this achieves is getting the bike to lean over, it can also initiate some of the correct dynamics.. Bikes never have square edges tyres like a car for a reason although the knobs sometimes make it look like it does. Bikes at speed use the tyre profile to turn. Eg like how an ice cream cone when rolled travels in an arc. A bike tyre is a bit like two cones joined together but more rounded. When joined together the cones can be leaned in both directions and turn both ways. The steering of bikes at speed have nothing in common with cars when going around a corner.
Not sure if you are doing this already but there are better ways at speed to get a bike on a lean than weight forward and to the inside. This should be done by counter steer (this isn't drifting). You give a subtle quick turn of the bars in the opposite direction you want to turn in. Ie turn the bars right to make the bike lean left. As soon as the bike leans back off and correct your direction (weird physics stuff about spinning objects, helicopters have to do this too otherwise they would fly off at 90 degrees to where the pilot pushes the stick. Same with a large cutting disc or angle grinder. They way it wants to twist is 90 degrees to the way you tried to move it.). You should be turning. You don't need to go fast to do this. Its also almost the only way you can turn a DH with slack head angle on flat gravelly ground. This is how you turn a motorbike. Drop handle road pushies, drop handle bar moto bikes etc all have geometry to help this happen too by shifting your weight around. Most mountain bikes less so.
Countersteer lets the bike lean without getting into a less stable position.
When turning the way I used to with the weight forward and inwards the following used to happen:
-it achieves lean and a bit of counter steer but not in a strong way
-back end used to break loose, unless I got may weight back to neutral in time
-sometimes I used to spin out
-used to low side or high side myself
-used to loose too much speed as it initiates a slide
Flynny and others would lean a bike using counter steer without even thinking about it. In tight quick single track people also often unload the bike and get extra lean by jumping the back sideways.
They will also be turning their hips towards the direction they want to go.
Trying to turn left at speed by turning the bar left means your body and bike are trying to do opposite things and you just feel unbalance and generally go straight ahead or awkwardly left.
+1 to the elbow finger thing for brake set up. Wished I'd known this starting out. Poor brake lever position contributed to 3 months off riding after stuffing a jump and bottoming my fork. Unless everything's in line your wrist is in a weak angle. My cartilage got torn and my wrist bones spat sideways.
Some other good points too.
Not sure if this helps you or stuff you know already. It might help others. It would have helped me reduce the number of stacks when getting into riding.
Hi Simon, had a good read of your post yesterday and couldn't say I have been consciously aware of doing the pre flick of the handle bars, but as I said it's hard to explain what you do when it has become second nature. Luckily last night was race night and Rydal is the place for corners so I tried to be more aware of what I was doing with out changing what came naturally (Harder said then done TBH as you start to over think things and I had a shocker in the first lap...)
I can't say I was doing the bar flick exactly as you describe but on certain corners I found what I did was shift/lean the bike to my outside just before the corner and then swing it back under me to bank it into the apex. Which I think achieves pretty much the same thing. Plus gets the bike to the outside of the trail before swinging into the apex.
There is also a similar technique the DH guys use on high speed rough/loose corners where the pre lean for the corner. ie say they are approaching and rough high speed right hander. On the approach they will lean out to the the right, keeping the bike upright, then as they get to the corner they the swing the bike in under them into the normal cornering position. Again I think would achieve a similar thing as your bar flick.
But speaking of starting wide and finding the apex, another common mistake is riders "squaring" the corner ie start turning in, then have to readjust and turn again mid corner and again on exit. If you can, start wide, hit the apex and finish wide all in one smooth turn. sometimes you need to go slow to go fast, ie slower into the approach to get a nice smooth line to hold faster exit speed.
Yep! We're saying the same thing. Throwing the bike wide then bringing it back in is the same bar movement. Second nature after a while and can be subtle. Same with the high speed DH term.
You describe what I do in a corner much better.
Its something I was taught by someone who is very handy on sports bikes and something covered in some motorcycle texts which is why I thought it topical. It's also in Brian Lopes book on how to ride a mountain bike. That's probably why I think about it from the bar motion.