rim brake vs disk in wet/misty conditions

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Boshk
Posts: 462
Joined: Wed Jul 19, 2017 2:59 am

by Boshk

Not a flame, just 1st experience.

I've always been a fair weather rider, if its raining outside, I don't ride or I ride on Zwift but today I went out with a bunch of RCC guys up to the highest point in Hong Kong which is only around 3500' high. Hard for me....easy for some of you I know.

Near the top, it was cold, windy and misty with light rain. naturally my standard Zonda rim wheels were wet.
I always thought I setup my campy Chorus rim brakes pretty well....for a novice. This morning was an eye opener......I've never used that much braking ever, I had doubts on the descent, admittedly I was using them more than the other guys since it was a new route for me, didn't want to fly off the edge.
I was on the campy hood ,holding both front and rear (rear less) brakes pretty hard and my speed was just ok.
Braking when the rims and pads are dry vs wet is like night and day....to me anyway.

I know there's a lot of debate still, especially from more advanced riders about rim vs disc, but I actually wished I had disc today. One guy blew out his tube....not sure whether it was from the heat or from a spike on the ground.

-I have no idea how you guys with full carbon wheels on rim brakes race or ride in pouring rain.....how do you even control your speed on steep descents?
-I found the braking portion of my rims are not clean, there's a small amount of black grease-like residue on it....I air dry my drivetrain after cleaning, lube my chain with RnR Dry then wipe off any excess with dry cloth....so I'm wondering how both front and rear rims have some...not a lot of this residue. I'm sure it affects the braking in wet conditions.
Any suggestions to cleaning it?
Last edited by Boshk on Sat Feb 17, 2018 7:56 am, edited 2 times in total.

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AJS914
Posts: 5397
Joined: Tue Jan 28, 2014 6:52 pm

by AJS914

Just scrub it off with soap and water. Scrub your brake pads too.

There are scenarios where discs can be better. It sounds like you found one.

alcatraz
Posts: 4064
Joined: Mon Aug 29, 2016 11:19 am

by alcatraz

If you are a heavier rider you generally can't expect to keep the same speeds descending as lighter riders in the bunch without taking greater risk.

They might furthermore have better calipers/brake pads/rims.

Whats the grade on those slopes? Even 7-10% can get scary to descend when cold and in some moisture.

I had a phase when I started dreaming about disc brakes but it passed. It did make me look over the brake system a bit. Check which pads are good in allround conditions. For alloy rims I get amazing bite with swisstop black for example.

Descend in the drops and hang your ass off the back to get better weight balance and less hand pain. Be crazy light on the rear brake in corners. It's easy to forget that it can lose traction easily while descending if you havent tasted the tarmac in tight corners before. You can brake on the wheel you have weight on.

/a

Boshk
Posts: 462
Joined: Wed Jul 19, 2017 2:59 am

by Boshk

AJS914 wrote:
Sat Feb 17, 2018 6:58 am
Just scrub it off with soap and water. Scrub your brake pads too.

There are scenarios where discs can be better. It sounds like you found one.
Will do, I'll take the wheels off and give the rim part a good wash and scrub the pads. Thanks
alcatraz wrote:
Sat Feb 17, 2018 8:27 am
If you are a heavier rider you generally can't expect to keep the same speeds descending as lighter riders in the bunch without taking greater risk.

They might furthermore have better calipers/brake pads/rims.

Whats the grade on those slopes? Even 7-10% can get scary to descend when cold and in some moisture.

I had a phase when I started dreaming about disc brakes but it passed. It did make me look over the brake system a bit. Check which pads are good in allround conditions. For alloy rims I get amazing bite with swisstop black for example.

Descend in the drops and hang your ass off the back to get better weight balance and less hand pain. Be crazy light on the rear brake in corners. It's easy to forget that it can lose traction easily while descending if you havent tasted the tarmac in tight corners before. You can brake on the wheel you have weight on.

/a
I'm not that heavy, 68kg. I was doing what you suggest, my butt was off/just on the rear portion of my saddle, lucky I didn't loose traction on the rear, I was quite hard on it thinking my butt is over/close to rear wheel.

It probably did help my rims weren't super clean....good experience.

Gradient from mousing over my Strava graph, ranges from 6-19% but they weren't crazy long consistent steep descents, still had me on edge.
more practise and more riding!

alcatraz
Posts: 4064
Joined: Mon Aug 29, 2016 11:19 am

by alcatraz

I ride in asia as well. Some other riders here get crazy skinny. A friend is 183cm and 55kg. :lol:

68kg is not a lot. I wouldn't go disc brake in your case and I like to climb. However that's not to say you can't benefit from them. If you are more concerned with feel/safety/consistency and less with weight/speed you might be more inclined than me to make the shift to disc brakes. It almost never rains where I live, unlike HK.

There is also the option of n+1. A dry and a wet weather climber. :lol:

/a

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corky
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Location: The Surrey Hills

by corky

Experience counts for a lot......knowing how your bike reacts to changes in conditions enables you to know how to handle it.

Also IME if you run discs in damp conditions you need to develop a deaf ear to the banshee wail.....

fromtrektocolnago
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by fromtrektocolnago

not going to suggets that disc wheels do not hold advantages in wet weather, but disc are no panacea either. tire tread, size and grip matter a great deal too. if the roads don't have grip, braking on them will not be optimal.
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liam7020
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Joined: Tue Jul 27, 2010 10:04 am

by liam7020

Perhaps you need to ride more in the rain - it's an essential skill every biker should master. For wet braking on alloy rims I've found Kool Stop Salmon pads to be the best.
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Boshk
Posts: 462
Joined: Wed Jul 19, 2017 2:59 am

by Boshk

liam7020 wrote:
Sat Feb 17, 2018 10:42 am
Perhaps you need to ride more in the rain - it's an essential skill every biker should master. For wet braking on alloy rims I've found Kool Stop Salmon pads to be the best.
completely agree, something I need to do.

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silvalis
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Location: Aus

by silvalis

While I'd opt for discs any time it's wet, I would very much +1 on the koolstops or swissstop bxps. Massively better braking in the wet. I went koolstop salmons last time around and feel it edges out bxps in the wet ever so slightly. Both heaps better than the standard campy sr brake pads it replaced.
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ODC
Posts: 373
Joined: Mon Aug 14, 2017 9:40 am

by ODC

This year i changed from rim brakes to disc brakes and for me it is a huge improvement in wet and also in dry conditions.
Why a huge improvement? I live in Belgium/Flanders so it is a lot of turning what is difficult to compare it with a long decent.
In rainy conditions disc brakes are going to be more noisy then rim brakes but that is nothing in comparison with the better braking performance.
And I also don't understand the bullshit don't buy disc brakes for climbing. Changed from the new slr01 rim brake to the new slr01 disc and the total bike is only 100 gram heavier.

bm0p700f
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by bm0p700f

my disc brake bike is 15kg with panniers yesterday I was slower than a sloth up hills. however in the wet you can stop I value that alot.

Riding hills in the wet can be hairy but the more you do it the better you get at it but it never feels right. With disc brakes you only have one worry tyre grip, no to tyre grip and whether the brakes are going to slow you down enough.

robertbb
Posts: 2179
Joined: Thu Jul 23, 2009 3:35 am

by robertbb

Zonda rims don't have the best braking surface to begin with, even in the dry. I imagine they suck in the wet. I've been doing some testing (which I plan to report on here) running Zonda C17's and non-mille Shamal C17's on the same bike, with same tubes/tyres, same pressure, same brake pads (Campy 11 standard). This includes running one of each front/rear... coming home, swapping, doing same loop... and though I have not yet finished testing in all combinations, all conditions, all kinds of roads... I think the love for Zonda's is really overdone - nowhere near Shamals by any measurement.

My point: Don't compare disc vs rim. Because not all rims are created equal, and braking on some is simply excellent. As has been said above, probably even better with aftermarket pads (I'm yet to go down that path but will at some point).

Stueys
Posts: 673
Joined: Sat Nov 22, 2014 1:12 pm

by Stueys

Swisstop for me, makes a big improvement on alloy rims especially in the wet. I ride a rim bike with carbon rims and a disc bike which I use in winter. Disks are significantly improved over rim brakes in wet conditions, especially if you’re riding carbon rims. I’ve no plans to change my nice bike soon but I suspect I’ll look pretty hard at disc options when I do, the advantages are clear and the disadvantages are slowly being eroded.

bm0p700f
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by bm0p700f

the shamals milles have a surface treatment though. compare like with like. alloy rims without surface treatment tend to brake in a similar way - crap in the wet. ceramic like treatments can improve matter though.

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