K2 / Proflex Riders Group
General => Tech Forum => Topic started by: keen on August 06, 2003, 04:36:53 pm
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I have been running Avid disc bakes w/ XTR levers for the past 6 months. Most of the riding has been fireroads, wide open downhill etc., worked fine. I just started running singletrack and what I find is that I am over braking on the technical down hills. I can say this isn't a good technique to stop forward momentum- good for an endo. I know I should stay off the brakes but I have a hard time modulating them @ slow speeds. I am tempted to throw my V brakes back on but this seems like a step backwards. Any advice? I really like the Avids for fast downhill. Another thing to note is the XTR's may not be the best match for disc's? Thanx
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(http://www.avidbike.com/2_cpsdiskbrakes/media/mech_diskbrake_large.jpg)
i was going to get a set of those and use them on my xtr setup (shifter/brake lever combos)
this may sound kinda screwy but can the throw on the arm be adjusted to decrease leverage (file into the arm or remount the cable)
or, perhaps remove the pads and maybe carve out say the center section of pad (vertically or horizontally) reducing surface area to the rotor.
the xtr's should have an adjustable throw as well at the lever - pull the lever back slightly and you'll see where the cable end sits - that pocket can move back and for about 3/8" and is limited by an allen screw - i'd try adjusting the limit screw so you adjust the leverage ratio -
just a few random thoughts -
OP
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If you have tried the settings OP suggests and your still not happy you could try a different compound pad (eg a harder compound), try EBC or fibrex there are probably other pad manufactures you could try, maybe some others on the forum may know of some.Simon P.S stick with it I'm sure you'll sort it out. [smiley=nod.gif]
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A couple thoughts.
1) Speed Dial Avids levers can adjust the leverage with a hand twist screw. I've got really old SD 2.0 Avids where the SD really comes in handy.
2) Adjust the grab point closer to the handle bar. I was talking a DH'er that's raced on the national level. He recommended doing that to reduce arm pump on a long DH. The side benefit seems to be minimizing panic braking.
3) Practice, practice practice. I use to have my Speed Dials set with low leverage. As my modulation got better, I've dial them up.
The only problem I've encountered once in a while is the front/back braking being unbalanced on technical downhills. I just hop off the bike and turn the red knob on the offending brake.
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I measured the distance between the cable eyelet and the lever pivot point on my XTR- it is less than my Avid levers. This means less cable pull but @ a faster rate? Whenever I used canti levers w/ side pull brakes the modulation sucked- they were on or off. The XTR's are set up for the most cable pull. This should provide the best modulation, correct? I run integrated levers/ shifters so an Avid lever won't work. I'd say 50% my problem but not sure about the XTR's as I havn't ridden any other set-ups.
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my suggestion is for you to get a 8 inch rotor and adapter...you can do it with avid disc..it sould work pretty well...do remember you need to break into the brakes pad first...ride around, do some breaking and pour some water onto the rotor...do this a couple of time and it should be broken in soon..
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Rawwill- You have got to be joking [smiley=disbelief.gif] ???
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hehe....which part?
the breaking in of the pad is true...try it if you don`t believe it...
as for the 8" if youare planning to go for a fast and long downhill ....it only coast 20-30 bucks extra.. [smiley=nod.gif]
then again what do i know. [smiley=laughing.gif]..well show you guys my bike as soon as it is done powder coated..hehe..
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Two thoughts:
1) The Avid Speed Dial levers mentioned above are great. If you can't get your brakes to modulate well with them, then the problem isn't the bike!
2) What kept me from endo-ing more than anything else was raising my front end. When I switched from a 3 inch fork to a 4 inch fork, I also added a little over an inch of spacers to my steerer, which raised my bars considerably. The difference was amazing. Before the change, I often felt like I was going over the bars when I braked (and in fact, I did several times). Since raising the bar, I have ridden some serious terrain without ever feeling like braking was causing me to go over the bars. The shift in my center of gravity relative to the bars has been amazing. When I brake, I feel like I'm going into my bars, not over them.
Just some thoughts...
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Matno- I am running 3" riser bars w/ 25mm spacers and a 5" front fork, bike feels like a motorcycle. I am 6'4" so my center of gravity is up there. I don't remember overbraking w/ my V brakes. I seemed to have ridden faster w/ the V's cause they wouldn't slow me down unless I really pulled on them.
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Wow. You certainly don't have a problem with your bars being too low, unless you're riding a Large frame instead of a WayBig - at 6'4" a Large would definitely be too small. However, with that kind of a rise on the front, I don't think it really matters what size frame you're on (the headtube might be a little different, but not a ton).
I would recommend just practicing braking technique. That's how I got comfortable with my brakes. (I've also got Avid discs). Just go to a nice soft grassy area and practice two things: stopping hard from a full-sprint (using your front brake), and nose wheelies. Nothing improved my braking as much as getting comfortable with nose-wheelies. Of course, I went over the bars a few times in the process, but now I feel like I can modulate my brakes significantly better. In fact, my riding overall improved the most when I learned to use my front brake at least 80% of the time instead of the rear.
If that doesn't work, you can try opening up the gap between your pads and the disc rotor (like someone mentioned above, I believe). Open it enough so that you barely have enough room to squeeze the levers to a full stop. It's worth a try...
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I admit a lot of the trouble comes from poor braking technique. I did have a couple of freinds, which are V brakes users sample my brakes. All stated the performance was much better than V's but a little grabby. I'll just have to practice my braking, as I really don't want to go back to V's, nor do I want to dump my XTR brake / shifters for pods n' Avids.
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Less cable pull=more leverage more cable pull=less leverage
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Less cable pull = more leverage = less modulation = XTR. There is a detailed thread on mtbr/ brake time/ "power vs. modulation".
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it is not unheard of to run a disc brake system in the rear and v's in the front -
OP
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I admit a lot of the trouble comes from poor braking technique. I did have a couple of freinds, which are V brakes users sample my brakes. All stated the performance was much better than V's but a little grabby. I'll just have to practice my braking, as I really don't want to go back to V's, nor do I want to dump my XTR brake / shifters for pods n' Avids.
A couple thoughts.
I noticed that after breaking in the Avids, they feel real strong, maybe even little grabby. After more usage the brakes are still strong, but not as grabby.
Another thing is after I switched to Avids, I also switched to single finger braking. It felt weird at first, but I stuck with it. My braking is definitely better with single finger and I now have four fingers hanging on to the bar. If you do decide to try single fingering, do it in easy braking areas. The transition was difficult, but worth it for me.
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some good ideas but the best one is adjust the throw of the brake lever and learn to ride singletrack. it's different than fireroads. i always have trouble adjusting myself, too.