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  1. #1
    Weekend Warrior
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    Drilled my Roundagons out today.

    I was sick of getting crap stuck in my pads and rotors as the roundagons don't clear out the debris well enough. I also don't want to toss good rotors (1.9mm thickness) for a pair of $50 rotors. I noticed upon further inspection that there is a line that goes in between the upper and lower holes continuously. So i thought, let's drill the holes out just a bit (so the upper and lower overlap) and hope that debris has a chance to clear out.

    It wasn't easy but after breaking a cobalt drill, i got myself some cutting oil, another cobalt drill and drilled all the wholes out to 1/4" and on the 185mm rotor i drilled every third upper hole to 3/8". I had to sand the holes down to prevent any raised edges.

    I only got a testride in today, but tomorrow I'm hitt'n an Urban Ride. Let's see how they perform. I'll post pictures tomorrow.

  2. #2
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    did you just enlage the holes or drill new holes?
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  3. #3
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    be sure to clean off with alcohol b4 riding. it seems obvious but you probably don't want cutting oil on there

  4. #4
    TNC
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    Cool...reminds of the early days of motorcycle discs when hardly any were drilled...only the trick racing stuff. We used to drill our own discs on a shop press with plenty of oil and bits. Even though bike rotors are thinner, it's a bit of work as I'm sure you found out. You gotta show us a pic.

  5. #5
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    Drilling is too complex for me, I cut out Vs in to sweep where the holes miss

  6. #6
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    You must have one hell of a loop where the hose comes from the bike to the caliper since it's angled upwards.
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  7. #7
    ride hard take risks
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    Quote Originally Posted by TNC
    Cool...reminds of the early days of motorcycle discs when hardly any were drilled...only the trick racing stuff. We used to drill our own discs on a shop press with plenty of oil and bits. Even though bike rotors are thinner, it's a bit of work as I'm sure you found out. You gotta show us a pic.
    Ahhh those were the dayz.
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  8. #8
    The Mud Stud
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    Im sorry to say this, but roundagons are really crapagons. In everyones opinion who rides them. They pulsate, make noise, fade and are weak. I switched my front from a roundagon to a hayes v6. WOW. Not only does it clean itself better, it stops harder, and never fades. The rear is next.

  9. #9
    Weekend Warrior
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    Here are pics of the rotors. I drilled out the existing holes as there isn't really any other place to drill with them. I didn't drill for ventilation i drilled for "Crap Removal"

    It seems to work just fine.

    The problem with the roundagons is that they don't clean well, the rotors are strong, heavy, and seem to do a pretty good job. I would say there is more stopping power with the Roundagons than with the G2 or G3, but i think that's because there is so much raw surface area. I though let me try before I drop 2x50 bucks for new rotors.

    And I did it without a drill press! Once the cutting oil was applied that drill went through like butter at minimal RPM. Without the cutting oil that thing wouldn't move and I destroyed a cobalt (harder than Titanium) drill.
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  10. #10
    Weekend Warrior
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    P.S.: See the lines on the inside of the rotor, they used to go continuously throughout the rotor as debris gets caught in the pads. Now that these holes are overlapping (theoretically) it will clean out anything stuck in the rotor.

  11. #11
    TNC
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    Quote Originally Posted by Dirt Bringer
    Im sorry to say this, but roundagons are really crapagons. In everyones opinion who rides them. They pulsate, make noise, fade and are weak. I switched my front from a roundagon to a hayes v6. WOW. Not only does it clean itself better, it stops harder, and never fades. The rear is next.
    Well, don't you think that the reason behind some of those performance issues you mention is because of the lack of proper drilling? In those early motorcycle disc brake days, we weren't just drilling those solid rotors to look cool, run cooler, and lose a little weight. Even brake squeal was greatly diminished by a decent drilling pattern. Braking performance increased notably. I doubt BB5/7 rotors are made out of inferior material as compared to G2/G3 models. They're probably just heavier and undrilled which leads to some of the issues you mention. So, while you're basically correct that roundwagons are a little inferior to many other rotors in their delivered state as far as braking performance goes, some drilling as achieved by the OP probably does wonders to improve the performance. I don't think most of us will go to these lengths, to improve the performance of such a basic rotor, but the OP made the attempt, and my hat's off to his efforts.

    We drilled solid motorcycle rotors in the old days and achieved very good performance increases, and I see no reason why it wouldn't work in this case for the BB5/7 rotors...even though most of us would rather just buy a ready-to-ride disc rotor.

  12. #12
    The Mud Stud
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    You know I never thought of that, but my new hayes v6 rotors have massive drilling and slotting, and they do stop much better, and do not heat up as much, as well as also self clean better. I wanna change my front rotor with a larger one (considering it at least) but this drilling is really a very good idea. I dont like the way the roundagons have a high/low/high contact area as they rotate though...causes pulsating, strange...

  13. #13
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    I'll admit, when I saw the thread title I was already reaching for my flame thrower, but it looks like you did a really nice job. Go ride around in some mud and let us know how it works.

  14. #14
    Weekend Warrior
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    I wonder if I countersink the holes if it would help clean the pads or if it's going to further embed debris? Even though the Roundagons are crap in stock form, they seem to offer more breaking power than the G2 or G3 rotors. I haven't had pulsating problems once they were adjusted correctly. I've been looking at various rotors from various manufacturers, however the only ones I really like start at $90 each. Too rich for my taste...

    I'll let you know by next weekend how they do in mud. It seems that every Off-Road track here in Central Florida has enough Muddy sections to test these out properly I'll be doing an Urban tonight where I can really test these rotors and see if I feel a difference.

  15. #15
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    Had my first real ride last night since I drilled my rotors and I must say i did a pretty good job with them. They worked perfect, no pulsating or other annoyances people usually associate with the crapagons. This weekend I will hit the mud trail, lets see how they do there, but they passed the first test so far.

    I would definitely recommend everyone to drill out their roundagons if they don't want to spend $100 on a pair of G2 or G3 rotors.

  16. #16
    Meh.
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    I have a 185 Polygon rotor if you want it. And some v6 Hayes rotors too.

  17. #17
    The Mud Stud
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    How much for the v6 rotors?

  18. #18
    ride hard take risks
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    Quote Originally Posted by Dirt Bringer
    How much for the v6 rotors?
    Special broken in pricing $55
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  19. #19
    The Mud Stud
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    Right. lol!

  20. #20
    Weekend Warrior
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    Here are some better pics;

    BTW, went out to a nasty trail yesterday, got mud into my rotors by riding into deep, muddy water. Cleared out all the crap within 100 feet, my chain wasn't that lucky. I had to break a few times and the squeak and grinding went away immediately. It cleared out all the gunk and grime very well. I'm going to help a friend drill out his rotors this week as well.

    Once I figured out how to drill them properly the drill went through like butter. Just use very, very low speed when drilling. Don't forget to sand down the holes or it will eat through your pads.
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  21. #21
    Lets RIDE!
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    Just wanted to say I did this mod to my BB7 front 185mm roundagon rotor last week. It works. It cured the squealing and improved the braking performance in wet/muddy conditions.

    Very easy to do on a drill press. With a sharp bit (I used a standard HSS bit), lowest speed, go slow, oil for cooling/lube, and a flat piece of hardwood to back up the cut, you'll get a very clean hole. A quick sanding with 400g wet/dry paper wrapped around a flat block removes any burrs, clean up the oil with hot soapy water followed by alcohol (denatured for the rotors, Long Trail Summer Ale for me) and you're good to remount and ride. Thanks for posting this Dale.

    JZ
    Last edited by Jim Z in VT; 08-30-2009 at 05:53 PM.
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  22. #22
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    Hey Dale, many thanks for posting this thread

    I'm planning to try your mod on a spare 160mm roundagon first, and if all goes well I'll probably do another 160mm & 185mm rotor as well. Just one small question: I'm a bit confused about exactly what hole-diameter you suggest for the inner and outer holes? In particular, the 'every 3rd hole' bit got me confuddled. Can you explain it for dummies like me?
    Brisbane, AU

  23. #23
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    Quote Originally Posted by Dirt Bringer
    Im sorry to say this, but roundagons are really crapagons. In everyones opinion who rides them. They pulsate, make noise, fade and are weak. I switched my front from a roundagon to a hayes v6. WOW. Not only does it clean itself better, it stops harder, and never fades. The rear is next.
    +1 on that.
    I bought two 185 mm Hayes V7 rotors from Ebay for 23 dollars Canadian shipped for both, new. Far superior rotor than roundagons... to me it isn't worth the amount of work, but some people enjoy doing these type of things, and he did a good job on it also.

  24. #24
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    Bump...

    Anyone else have any success drilling out rotors? Any additional tips (besides keeping drill bits cool)?

    I was debating going this route, enlarging the existing holes and possibly drilling new smaller holes as well. However, I'm hesitant if this is going to cost more in drillbits vs. upgrading rotors.

  25. #25
    Spanish rider
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    Quote Originally Posted by William_Cannon
    Bump...

    Anyone else have any success drilling out rotors? Any additional tips (besides keeping drill bits cool)?

    I was debating going this route, enlarging the existing holes and possibly drilling new smaller holes as well. However, I'm hesitant if this is going to cost more in drillbits vs. upgrading rotors.

    Unless you kill 10 bits or so I think it's cheaper to drill the holes. A decent drill bit is about 6$ and if you use it properly it may survive to the experiment
    A pessimist is an experienced optimist

  26. #26
    Never trust a fart
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    Make sure to use cutting oil. It will save your drill bits by keeping them cool.

  27. #27
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    Any light oil will work.....3-in-1, WD40, etc. Just keep a little puddle of it around the hole being drilled. And drill slow!

    Enlarging the holes was easy. Drilling new holes will be trickier, as you'll need to center-punch the location to keep the bit from wandering....and center punching might slightly warp the rotor.
    It's not about speed, it's about lack of control.

  28. #28
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    Quote Originally Posted by Jim Z in VT
    Any light oil will work.....3-in-1, WD40, etc. Just keep a little puddle of it around the hole being drilled. And drill slow!

    Enlarging the holes was easy. Drilling new holes will be trickier, as you'll need to center-punch the location to keep the bit from wandering....and center punching might slightly warp the rotor.
    I've used "smurf juice" at an old job (not sure what it is really called) and I use WD40 at home to keep bits cool.
    Good call on the center punch. I'm not sure if/how it would warp the rotor, but you have my wheels turning on any unintended consequences. I'm thinking if I have the rotor on a flat surface, it should be fine.

  29. #29
    Newt Guy
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    I aint drillin any holes in my brake rotors that aren't already there.

    Good luck.
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  30. #30
    Spanish rider
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    Quote Originally Posted by FrostyStruthers
    I aint drillin any holes in my brake rotors that aren't already there.

    Good luck.
    No body is drilling any holes that weren't already there, they just made them bigger
    Last edited by Pableras; 11-10-2010 at 11:57 AM.
    A pessimist is an experienced optimist

  31. #31
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    Quote Originally Posted by Pableras
    No body is drilling any holes that weren't already there, they just made them bigger
    I might give it a go.

  32. #32
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    Quote Originally Posted by William_Cannon
    I might give it a go.
    Drill press well secured rotor and as Jim said slow and lots of cooling oil. Kinda sounds kinky.
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  33. #33
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    Quote Originally Posted by Pableras
    No body is drilling any holes that weren't already there, they just made them bigger
    I aint drilling any holes BIGGER in my brake rotors that are not already that big.

    Good luck.
    Yes, steel is most certainly stronger than aluminum EVERY time.
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  34. #34
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    why not?

  35. #35
    ride hard take risks
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    FS you have made it known your not into experimenting cool leave yours stock and be happy. If someone wants to try an experiment as long as they are able to be responsible for their own actions right on for them being intelligent.
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  36. #36
    Newt Guy
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    Quote Originally Posted by dogonfr
    FS you have made it known your not into experimenting cool leave yours stock and be happy. If someone wants to try an experiment as long as they are able to be responsible for their own actions right on for them being intelligent.
    Yes, steel is most certainly stronger than aluminum EVERY time.
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  37. #37
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    Quote Originally Posted by FrostyStruthers
    I aint drilling any holes BIGGER in my brake rotors that are not already that big.

    Good luck.
    Maybe you should find a different thread to post in then?

    Works great, I drilled mine out months ago. Might go so far as to say night and day.

  38. #38
    Newt Guy
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    Quote Originally Posted by One Pivot
    Maybe you should find a different thread to post in then?
    What? So I don't agree with the drilling? Does that mean I have to post up my opinion about it in another thread?



    Works great, I drilled mine out months ago. Might go so far as to say night and day.
    Works great for YOU. Not going to risk it when it comes to ME.

    I'm sorry you disagree, but it is of no consequence really.
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  39. #39
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    Quote Originally Posted by William_Cannon
    I might give it a go.
    Alright, I drilled out to 1/4" on my 185 and 160. WD40 did a fine job of keeping the rotor cool. Then I wrapped 150 grit around a 1/8" bit and taped it to the base to speed up sanding the holes. Next, I wrapped 220 grit around the same bit and did a surface sand perpendicular to the rotor. I finished up with a hand buff with 220 and cleaned the rotor with some brake cleaner.

    They definitely sound quieter, but I didn't get a chance to do a real field test. If it doesn't rain this weekend, I'll be able to report back some results.

    I have an extra 160, if I get some time, I'll drill out the existing holes to a 1/4" and add some additional 1/8" or 3/16" holes for an experiment.

  40. #40
    I Tried Them ALL... Moderator
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    Those Avid Roundagons are the worst rotor Avid ever made; they squeal like a stuck pig, trap debris like hoarding pack rat and warp very easily, for a heavy rotor. Get the G2 - which is ideal, for the BB7.
    "The ONLY person who needs to race.....is the entrant"

  41. #41
    Newt Guy
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    Quote Originally Posted by Zachariah
    Those Avid Roundagons are the worst rotor Avid ever made; they squeal like a stuck pig, trap debris like hoarding pack rat and warp very easily, for a heavy rotor. Get the G2 - which is ideal, for the BB7.
    I use them because on a bike as they don't give me issues, but both bike shops in this area have told everyone to bring them in for a trade out to the G2 as, "The roundagon has been recalled".

    I tried to find info on this "recall", but I have been unable to find anything out about it just searching around. This began a few years ago around here and they are still doing it.

    Yes, steel is most certainly stronger than aluminum EVERY time.
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  42. #42
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    Quote Originally Posted by William_Cannon
    Alright, I drilled out to 1/4" on my 185 and 160. WD40 did a fine job of keeping the rotor cool. Then I wrapped 150 grit around a 1/8" bit and taped it to the base to speed up sanding the holes. Next, I wrapped 220 grit around the same bit and did a surface sand perpendicular to the rotor. I finished up with a hand buff with 220 and cleaned the rotor with some brake cleaner.

    They definitely sound quieter, but I didn't get a chance to do a real field test. If it doesn't rain this weekend, I'll be able to report back some results.

    I have an extra 160, if I get some time, I'll drill out the existing holes to a 1/4" and add some additional 1/8" or 3/16" holes for an experiment.
    Field test complete.

    There was certainly a modest improvement, but I think I'm going to go with the G2 and in my "spare time", I'll eventually work on modifying the roundagons.

    What's the difference between the G2s and G3s?... I'm finding them for the same price.

  43. #43
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    G3 is lighter, by a few grams. However, they are prone to high-heat warping...something the heavier, trusted and true G2 does not do.
    "The ONLY person who needs to race.....is the entrant"

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