Possible to upgrade to 180 (or203) rotors from 160?

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Possible to upgrade to 180 (or203) rotors from 160?

Postby fatoldman » Tue Dec 10, 2013 4:26 pm

I have a couple of bikes that I'd like to improve the braking systems on.

1. Specialized Sectuer disc - after running the bike for less than a month, the bike tech told me that I was "over-braking" as the rear disc was showing signs of over-heating. I very much like being alive and do not want to descend Cat 3s without braking on open roads. So, I'd like to improve the cooling of the rotors and I wonder if increasing the surface area (by increasing the diameter) might be the way to go. As I see it, I would need to purchase the appropriate mounts for the bigger rotors and the bigger rotors. This bike is currently fitted with Avid BB mechanical brakes and I don't think it should be a difficult changeover.

2. Trek 6500 MTB - the brakes on this bike (Shimano Deore M575 hydraulic on 160mm rotors) have been pretty good up to now but it is time to replace the rotors which are quite well worn. I thought it might be a chance to bump up my stopping power by fitting 180mm rotors. Then I read a review of the 180mm adaptor mount that mentioned to be careful that your forks could take the extra forces of braking on 180mm rotors. I am not entirely sure that this is a valid warning as I would have thought that the "fail point" under braking would be the traction between tyre and riding surface rather than the fork but I am not scientist so...

Is upgrading from 160mm rotors to 180mm rotors feasible / advisable? Is my reasoning for upgrading sound? Any comments will be welcomed - even you are only telling me that I am an idiot for thinking about doing this :)
If there was a pessimism competition, I probably wouldn't qualify.
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Re: Possible to upgrade to 180 (or203) rotors from 160?

Postby RickH » Wed Dec 11, 2013 12:20 am

On point 1 - it is better for your brakes, whether rim or disc, to try to not use the brakes all the time on hills. If you learn to let the bike run until you need to brake, or reach a speed you are unhappy with, then scrub off some speed, your brakes will be happier and your average speed will probably be higher to boot. When you do need to brake continually, learn to switch between brakes as appropriate (mostly front approaching a bend, a little rear if you need to keep speed in check round the turn, alternating on the straight). You do need to learn the capabilities of your bike in different conditions. :D

Rick.
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Re: Possible to upgrade to 180 (or203) rotors from 160?

Postby fatoldman » Thu Dec 12, 2013 2:02 pm

Thanks Rick. I am, by no stretch of the imagination, a skilled road cyclist. I will give this a try. I do have the problem of being "chunky" (18st) - so the speed really does have to be kept under control on steep descents to avoid momentum pulling me off a safe line on the corners. However, with the upgraded brakes and your technique, the next trip over the hills should be a lot more fun.
If there was a pessimism competition, I probably wouldn't qualify.
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Re: Possible to upgrade to 180 (or203) rotors from 160?

Postby Andy_M » Sun Dec 15, 2013 7:43 am

As you have worked out, the process of upgrading is very simple - new disc and a new adaptor to fit in between the caliper and frame / fork. However there may be a physical limit on how big a disc will fit, as the frame/fork is often shaped to allow the disc to fit, so you may need to be careful with that.
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Re: Possible to upgrade to 180 (or203) rotors from 160?

Postby mtbnoob » Wed Jan 15, 2014 3:26 pm

In my opinion if you want to ride with peace of mind whenever you go, and whatever the riding conditions are, a front rotor of at least 180mm in the front is a must.
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Re: Possible to upgrade to 180 (or203) rotors from 160?

Postby Milfred Cubicle » Wed Mar 12, 2014 5:45 pm

I would advise checking whether your fork can take more than a 160 rotor first. I've seen a 203mm rotor destroy a fork designed for 180mm, and only by luck it didn't destroy the rider too! If it can take a bigger rotor, great, but shop around for a well vented rotor. As stated by others, discs, especially hydraulics, don't like prolonged application. Better control speed by shorter, more powerful bursts. I'm not sure, but Hopetech and maybe Superstar Components make very nice vented discs.
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