The argument against using tools:
There are a few different companies out there who manufacture tools made specifically to straighten rotors, simply pinching the rotor and acting as a lever to allow you to bend it easier. Some are designed to be used two or three at a time, with one or two holding a section of the rotor in place while the remaining tool acts as the lever. There is even a feeler gauge that allows you to see exactly how far the rotor is out, but nothing works as good as using your bare hands.
There are a few issues with using metal levers (this includes crescent wrenches as well
) to straighten rotors, but the first is how easy it is to actually bend the rotor while using these tools. That isn't a good thing? Nope, especially for the home mechanic who might not be doing this repair that often. The extra leverage allows you to very easily bend the rotor too far, making the problem worse than it was when you started the repair. While it would be easy to blame the mechanic and not the tool, some bent rotors only require the slightest amount of force to straighten and some require much more, but a rotor tool can make it difficult to feel the amount of force that you are applying. Using your hands will give you a much better feel for what you are doing, allowing you to make smaller adjustments at each go.
Rotor straightening tools are often quite skinny as well, and applying pressuring to a very focused point on the rotor may do more harm than good. It is often much more effective to use your thumbs to spread the force out as you work the rotor back to straight. The worst case scenario is when so much force is applied by using a rotor straightening tool that it actually kinks the rotor where the tool makes contact, instantly turning it into scrap metal.But aren't your hands dirty?
When was the last time that you cleaned your rotor straightening tools? Your hands have oil on them right now, even if you've just woken up and haven't touched anything yet, which is why you'll want to clean them before doing this job. Getting that oil or grime from your hands onto the rotor will only be detrimental to the performance, so if you are going to try and straighten your bent brake rotor by using your hands you'll want to make sure that they are clean. Very clean. Wash them thoroughly, being sure to rinse off any and all soap that you've used, and then dry them with a towel that you know is clean. Alternately, you can just throw on a new pair of nitrile gloves and be done with it. Some helpful pointers:
• Much like truing a wheel, this is one of those repair jobs that will only get worse if you try and rush it. Take your time, find the exact
place where it needs to be straightened and make very small adjustments at each go. You want to avoid bending the rotor too far or doing it in the wrong place, both of which can cause the rotor to have a wave bend where it is out of true to both the left and right. That's when things can start to get tricky...
• While a small to medium gentle bend in a rotor can usually be trued out with great results, sharper kinks are likely going to be a death blow. Having said that, it certainly doesn't hurt to try and straighten anything.
• The rotor may be out of true in multiple spots, but only work on one at a time to keep things simple.
• The edges of a rotor are usually quite sharp. Be careful not to cut yourself!What's needed:
• Your clean hands (nitrile gloves help
• A clean rag
• A sharpie
• Brake clean
Step 1. You first need to identify the exact spot where the rotor is out of true. It is easiest to let the rotor tell you where it's rubbing the brake pads - instead of trying to peer down at the gap between the pads and rotor, listen to the sound it makes when it rubs. You may have to listen carefully, but slowly rotating the rotor through the caliper will tell you exactly where contact is being made.
Step 2. Use a black marker to indicate the exact position and how long the bend is. Only mark the very top edge of the rotor, not the braking surface. This will make keeping track of your progress much easier, especially if there are multiple locations on the rotor that are out of true. If there are multiple places that need attention, concentrate on one at a time.
Step 3. If you need to true the rotor by pushing it in towards the bike, wrap your fingers around the spokes and gently push with your thumbs. Go easy, you'll find that not much force is needed to make substantial changes. If the affected area is long, spread your thumbs far enough apart to straighten it. Apply pressure and then turn the rotor through the caliper to see how effective you've been. Repeat as needed.
Step 4. If the rotor needs to be pulled out away from the bike place one hand at the top of the tire to hold the bike in place and use two or three fingers to gently pull at the rotor. Again, start with only a small amount of force, working your way up to applying only as much pressure as needed.
Have you tried to straighten a rotor this way? Maybe you have a technique you want to share? Tell us about it below.
Step 5. Even though you washed your hands prior to touching the rotor you should still give it a good spray with a brake cleaner to rinse off any oils. Let it air dry.
Past Tech Tuesdays
:Technical Tuesday #1 - How to change a tube. Technical Tuesday #2 - How to set up your SRAM rear derailleur Technical Tuesday #3 - How to remove and install pedals Technical Tuesday #4 - How To Bleed Your Avid Elixir Brakes Technical Tuesday #5 - How To Check And Adjust Your Headset Technical Tuesday #6 - How To Fix A Broken Chain Technical Tuesday #7 - Tubeless Conversion Technical Tuesday #8 - Chain Wear Technical Tuesday #9 - SRAM Shift Cable Replacement Technical Tuesday #10 - Removing And Installing a HeadsetTechnical Tuesday #11 - Chain Lube ExplainedTechnical Tuesday #12 - RockShox Totem and Lyric Mission Control Damper ModTechnical Tuesday #13 - Shimano XT Crank and Bottom Bracket InstallationTechnical Tuesday #14 - Straightening Your Derailleur HangerTechnical Tuesday #15 - Setting Up Your Front DerailleurTechnical Tuesday #16 - Setting Up Your CockpitTechnical Tuesday #17 - Suspension BasicsTechnical Tuesday #18 - Adjusting The Fox DHX 5.0Technical Tuesday #19 - Adjusting The RockShox BoXXer World CupTechnical Tuesday #20 - Servicing Your Fox Float ShockTechnical Tuesday #21 - Wheel Truing BasicsTechnical Tuesday #22 - Shimano Brake Pad ReplacementTechnical Tuesday #23 - Shimano brake bleedTechnical Tuesday #24 - Fox Lower Leg Removal And ServiceTechnical Tuesday #25 - RockShox Motion Control ServiceTechnical Tuesday #26 - Avid BB7 Cable Disk Brake SetupTechnical Tuesday #27 - Manitou Dorado Fork RebuildTechnical Tuesday #28 - Manitou Circus Fork RebuildTechnical Tuesday #29 - MRP G2 SL Chain Guide InstallTechnical Tuesday #30 - Cane Creek Angleset InstallationTechnical Tuesday #31 - RockShox Maxle Lite DHTechnical Tuesday #32 - Find Your Tire Pressure Sweet SpotTechnical Tuesday #33 - Three Minute Bike Preflight CheckTechnical Tuesday #34 - MRP XCG InstallTechnical Tuesday #35 - Stem Choice and Cockpit SetupTechnical Tuesday #36 - Handlebars - How Wide Affects Your RideTechnical Tuesday #37 - Repairing A Torn TireTechnical Tuesday #38 - Coil spring swapTechnical Tuesday #39 - Trailside help: Broken Shift CableTechnical Tuesday #40 - Installing a Fox Float Air-Volume SpacerTechnical Tuesday #41 - Replace the Seals on Your 2011 RockShox Boxxer World Cup ForkTechnical Tuesday #42 - Clean and Lubricate Your Fox F32 Dust Wiper SealsTechnical Tuesday #43 - Thread Locker BasicsTechnical Tuesday #44 - Install a SRAM X.0 Two-By-Ten CranksetTechnical Tuesday #45 - VPP Suspension Bearing Service
to see their entire lineup of tools and lubes