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  1. #1
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    Questions about HD build

    I'm building up the HD and so far its going good other than a few issues. I'm running a DT Swiss 240's hub, The One FR brakes with an 8" rotor, and a Sram PG-980 9 speed 11-34 cassette.

    Here are my issues:

    1) When the chain is in the smallest gear it just touching the chain stay. How close is it supposed to be and is my cassette not compatible with the Mojo?

    2) My rotor has a slight wave, and I mean SLIGHT wave in it. When I put my caliper on try to line it up with no scrub no alignment works. The rotor is either scrubbing the pads or its scrubbing the actual grove machined into the caliper for the rotor to spin through but at no point is it not scrubbing anything. I used these rotors and brakes on my Rune and never ran into this problem. I even took my Dremel tool with a die grinding head and opened up the groove a bit more. Not too much to weaken it by any means but enough to help the scrubbing. I went to put new pads in the rear and when I actually managed to get the new pads in they were initially so tight on the rotor that the wheel doesn't turn for Sh@t. So I just put the old pads in for now but they still scrub enough to make noise and create drag which is annoying I was sure it wasn't going to turn but figured I would try it anyway. Then my thumb slipped off the caliper and actually went into the spoke of the rotor cutting though the side of my thumb and about 2/3 of the way across my thumb nail. So that was awsome.......

    Any run into these issues before even if it was with another frame? Any suggestions?
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  2. #2
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    1) it is pretty close on my shimano 10 speed casette but no rub.
    2) so are you saying that your rotor is warped? if so, get a new one.
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  3. #3
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    Could be a number of things. I would recommend you take it to your shop and have them work the bugs out.

    If the rotor runs parallel (with exception to to the warped section) with the opening in the caliper then it most likely has nothing to do with the frame. Even if it doesn't there could be a few different problems other than the frame (namely caliper issue, or adapter issue). The issue with the new pads leads me to think that you forgot to reset the pistons (or didn't reset them properly) prior to installing the new pads, or the brake was bled prior without resetting the pads which led to overfilling of the brake with fluid, or there's an issue with dirt in the caliper or one of your pistons is not setting flush in the caliper. The rotor can also be trued. Again a lot of things need to be working in sink to get a brake to work properly.

    Although the clearance is tight near the cassette you shouldn't be rubbing. Again this could be caused by a couple of things. Your crank spacing can affect the chain line, different frames are designed to run different spacing with regard to the BB/crank setup. The spacing on the hub or cassette could be off.

    Very rarely does something like this come down to a frame alignment issue. Have seen it but not with an ibis, I would recheck everything. If your confident that it's not a setup issue then I would take it to your local ibis dealer or LBS. They can double check everything. They should also have tools to check frame alignment.

  4. #4
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    Are Mojo's meant to primarily be used with a 10 speed setup? I hope I don't have to convert my 9 spd to a 10 spd because a new derailleur, cassette, shifter, and chain are going to get really expensive really quick. The rotor actually doesn't have much use on it and every rotor I've ever gotten seems like it had a very small amount of deflection in it. If it were laying on the table I think the amount of deflection would amount to about 1/32 to 1/16 of an inch. Maybe that's enough but there isn't a crazy amount of warpage or discoloration.
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  5. #5
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    You can run 9 speed - no problems there.

    1/16th is quite a bit on a rotor. If its not an abrupt bend then you can true it (experience gos a long way here). There's definitely an art to truing rotors.

  6. #6
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    Quote Originally Posted by SweatyBiscuit View Post
    Could be a number of things. I would recommend you take it to your shop and have them work the bugs out.

    If the rotor runs parallel (with exception to to the warped section) with the opening in the caliper then it most likely has nothing to do with the frame. Even if it doesn't there could be a few different problems other than the frame (namely caliper issue, or adapter issue). The issue with the new pads leads me to think that you forgot to reset the pistons (or didn't reset them properly) prior to installing the new pads, or the brake was bled prior without resetting the pads which led to overfilling of the brake with fluid, or there's an issue with dirt in the caliper or one of your pistons is not setting flush in the caliper. The rotor can also be trued. Again a lot of things need to be working in sink to get a brake to work properly.

    Although the clearance is tight near the cassette you shouldn't be rubbing. Again this could be caused by a couple of things. Your crank spacing can affect the chain line, different frames are designed to run different spacing with regard to the BB/crank setup. The spacing on the hub or cassette could be off.

    Very rarely does something like this come down to a frame alignment issue. Have seen it but not with an ibis, I would recheck everything. If your confident that it's not a setup issue then I would take it to your local ibis dealer or LBS. They can double check everything. They should also have tools to check frame alignment.
    I really don't think its a frame issue. It looks perfect and I actually rode it in the driveway in the first 5 gears without an issue. Just the sound of the rear brake a little bit. The chain gets really close to the chainstay and I was just worried it would be hitting it while riding down the trail. Looking at Ibis's website and what most people run it seems like a 10 spd setup is most popular. I know my spacing is correct for the BB/crank setup because I talked both E-Thirteen and Ibis on the subject and everything worked out fine. As for the brakes I bought a bleeding kit and was planning on shortening the lines a bit but apparently everyone is sold out of the kit to do it. I may have to order it directly. Is it hard to take these brakes apart and give them a thorough cleaning? Whats the best way to reset the pistons? I have new brake fluid and the bleed kit so I would be willing to try it myself.
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  7. #7
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    Quote Originally Posted by SweatyBiscuit View Post
    You can run 9 speed - no problems there.

    1/16th is quite a bit on a rotor. If its not an abrupt bend then you can true it (experience gos a long way here). There's definitely an art to truing rotors.
    ^^^This is good info.

    I run 9spd on mine and the chain does run close, I imagine 10spd might be a closer fit.
    If you can't cure it with some hub adjustment, you could try getting a 12mm ID shim and putting it between the hub and right side of the frame, or even try spacing the der hanger out a tiny bit with a shim, though I doubt shimming anything would be necessary.

    1/16th is a pretty big warp. Getting the warp out of one is a delicate process that, in my experience, leads to a rotor with warps in a few places. Go slow and in small increments when trying to straighten it.

    To properly bleed the brakes you need to put the spacer block between the pistons. The block comes with the brakes when you buy them, and may come with the bleed kit. Usually you take the pads out, use a screw driver or allen wrench to push the pistons into the caliper, stick the block in there, squeeze the lever until it's firm, then start the bleed process.
    Those who know, ride a Mojo AND a Mojo HD.
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    Ok, whatever, cold water on my bike boner right there.

  8. #8
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    To rest the pistons I would first pull the pads out and clean around the pistons inside the caliper. When I reset pistons I usually put the old pads in the caliper and use a tool that Park makes for this purpose (an old screwdriver will work but it's more likely to gouge the surface of the pads. When working with brake pads it's very important to keep everything very clean and free of oil, brake fluid or grease. With the park tool or screwdriver you apply leverage (carefully) to each pad until the pistons sit perfectly flush with the inside surface of the caliper (if they don't sit flush then there is another issue). You can also do this with out the pads (I prefer using the old pads to prevent damage to the pistons or caliper). For this method I would use a the boxed end of an open end wrench (the angle of the end of the wrench works well here). The pads should press in without much force. Applying the pressure to the center of the piston or where the center of the piston sits also helps. once the piston sits flush I would again clean the caliper and put the new pads in place.
    Be careful when you bleed brakes it's not hard but I've seen a lot of new pads that were contaminated by brake fluid. When you bleed always reset the pistons first. Then pull the pads and bleed the brake with out pads to prevent contamination of the brake pads. The formula site has pretty good instructions on brake bleeding.

  9. #9
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    If your rotor is constantly rubbing, I'd try shimming it first, before getting into truing or rebleeding. Formulas have notoriously tight pad clearance, so any anomalies are going to be magnified. Shims are your friend.

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  10. #10
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    Well I reset the rear caliper pistons and it seemed to help. I decided to keep using the old pads since they have about 3/32" left in them and both of my maintenance books say they don't have to be until about .5mm so I should be good for a while. There is still a little bit of scrub but its because I couldn't completely straighten the rotor and the scrub isn't bad. As for my chain coming close to the chainstay I'm going to call Ibis and talk to them. I noticed that when the chain is under tension it just clears the chainstay but not by much. With enough rough terrain I'm sure it would still contact the chainstay.I dunno, we'll see what Ibis says.....
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  11. #11
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    Quote Originally Posted by Crash Dummy View Post
    Well I reset the rear caliper pistons and it seemed to help. I decided to keep using the old pads since they have about 3/32" left in them and both of my maintenance books say they don't have to be until about .5mm so I should be good for a while. There is still a little bit of scrub but its because I couldn't completely straighten the rotor and the scrub isn't bad. As for my chain coming close to the chainstay I'm going to call Ibis and talk to them. I noticed that when the chain is under tension it just clears the chainstay but not by much. With enough rough terrain I'm sure it would still contact the chainstay.I dunno, we'll see what Ibis says.....
    I put some frame protector tape in the area to prevent it from getting too scratched up. Cut to fit and you are good to go.
    Those who know, ride a Mojo AND a Mojo HD.
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    Quote Originally Posted by benja55
    Ok, whatever, cold water on my bike boner right there.

  12. #12
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    I went to a LBS and besides all of them noticing how gorgeous the HD frame is they noticed my dropout was a little tweeked. The difference from the bottom of the rim to the top of the rim was a 1/4"-3/8" differince, quite a bit. They took care of that for me and tuned in my derailleur but they still didn't know why the chain was rubbing. I called Ibis again a Jeff said that different colors have different thicknesses and that normally its pretty tight clearances but they haven't really seen a bad rubbing issue. He said what would happen over time is that the chain would wear through the paint but not the carbon fiber. He said that the carbon is thicker and is extremely hard and that I wouldn't have to worry about the chain going through it. Since it only really rubs when not under tension I don't think I have much to worry about since that means I'll be free wheeling. I'll put some protection there like you said and give'r hell!
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