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Rotor sizing for a 69er/96er?

1153 Views 10 Replies 7 Participants Last post by 40hills, Sep 22, 2009

40hills

Discussion Starter · Jun 30, 2009

The simple answer is 185F/160R, but as a pseudo weight-weenie and a lightweight rider I'd like to know what I can get away with.

I currently have Juicy 7's on a Top Fuel 69er, but just won a set of Juicy Ultimates on fleaBay, so will be switching to those within days.

I am a lightweight at about 145lbs and ride a wide variety of terrain. In reality most of my time is spent on bumpy single track with fairly short ups and downs in central NC, but I ride in the mountains as much as possible (a couple days every month or so) on trails with very long and fast downhills (NC has the biggest mountains in the east). I've ridden many miles on the 185/160 setup which has all the stopping power I could want so I know it works great, but is it overkill for me?

Do you think I can get away with 160F/140R without smoking the rotors or pads? If not, what about 185F/140R? I do tend to be fairly aggressive on some of the downhills in racing or play situations where I'll approach turns fast and then kill speed in a hurry. Will a 160F be adequate for me?

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derby

· #2 · Jun 30, 2009

I've never seen a 140mm rotor, but if available at your light weight and for those local trails with a lack of long downhills a 160/140 would probably be sufficient. Keep your 180 rotor though, you might find those weekend long downhills require 180/160.

Maybe you could go to 160/160 and use sintered pads in front and weaker organic pads in the rear to better balance the need for more brake power in front, especially using a larger front wheel.

Only you can really know from testing what the minimum brake power is that you need, we each have different styles and strengths.

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amillmtb

· #3 · Jun 30, 2009

Not to get too personal, but how much do you weigh?

I would only recommend 160/140 to someone who is pretty light. I run 160/160 and I'm 145lbs. I could easily run 160/140, but I dont see the need to. I agree with Derby, running different pads could definitely keep high power on the 160 rotor in front while having a little less on the same size 160 rear.

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40hills

Discussion Starter · #4 · Jul 1, 2009

amillmtb said:
Not to get too personal, but how much do you weigh?

I would only recommend 160/140 to someone who is pretty light. I run 160/160 and I'm 145lbs. I could easily run 160/140, but I dont see the need to. I agree with Derby, running different pads could definitely keep high power on the 160 rotor in front while having a little less on the same size 160 rear.

Thanks. As I mentioned in my post, I weigh about 145

I took the 160/140 out this afternoon on some slightly hilly gravel roads and I think it will work just fine around my local area. I am likely going to be riding in the mountains later this week and will try it there. I think I might be pushing the limits in the mountains, but we'll see how it goes. I'll bring my other rotors just in case I decide to swap them out again.

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fedexil

· #5 · Jul 1, 2009

Go with Scurb Rotors

http://scrubcomponents.com/html/scrub_components_-_160mm_rotor.html

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revolution69er

· #6 · Jul 2, 2009

I started with FORMULA K24's in a 160/160 configuration...ended up replacing the front to 203mm and am very happy...have heard that the larger 29er wheel likes a larger rotor and can tell you from experience that it works great...I only need 1 finger on the front brake to get the job done

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40hills

Discussion Starter · #7 · Jul 6, 2009

fedexil said:
http://scrubcomponents.com/html/scrub_components_-_160mm_rotor.html

Very nice, but $145 each

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40hills

Discussion Starter · #8 · Jul 6, 2009

So I rode the past 4 days with the 160/140 combo in the mountains on moderate terrain with some fast downhills and it worked great so far. I didn't take it on the biggest and baddest routes yet though, and I'm wondering how they will work when wet. So far so good, but I need to ride with them more before I believe this setup will work full time.

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EBasil

· #9 · Sep 19, 2009

I'm running a 180/160 setup on my 69'er with Juicys and finding that it's enough braking power. It also looks good: the differential in rotor size mirrors the same for the wheels. I didn't do it for that reason, but several people have commented on that aspect.

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onespeedpaul

· #10 · Sep 21, 2009

a wise man once said: you're only as fast as you can slow down.

i like big 203mm rotors for my front wheels but that's just me.

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40hills

Discussion Starter · #11 · Sep 22, 2009

onespeedpaul said:
a wise man once said: you're only as fast as you can slow down.

... so true! :thumbsup:

I've been using 185F/140R and find that I have more confidence carrying speed closer to corners, stops, and turns than with the 160F/140R combo. FWIW, I think the 140R is plenty big enough for me on my 69er. While I've gone back and forth a bit on the front, I don't see that I'll need to put the 160R on again.

I have to remind myself though that this whole "debate" I'm having with myself on rotor size is only due to my weight-weenyism

Otherwise I'd just keep the 185F/160R and be done with it.

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