Disc v Rim brakes

General cycling advice ( NOT technical ! )
samsbike
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Disc v Rim brakes

Postby samsbike » 19 Aug 2016, 10:26am

I have summarised the arguments below but I still can't figure out if rim brakes are a better bet and why.

Note that I am not discussing touring here, where parts availability is crucial.

Disc brakes
Pro
1. better all weather braking
2. can run different tire sizes depending on bike - if that's your thing


Cons
1. Potentially harsher ride, due to the fork being built stronger (can be offset by better tire choice)
2. Wheels need to be dished - am not sure about the implications of this
3. Weight - about 0.5-1kg heavier than equivalent rim braked bike, although this is a moot point according to some manufacturers
4. Need to be more careful in handling so as not to bend the discs.

I get that a summer only bike may run rim only brakes, but personally I dont see the point, of restricting the bike you enjoy the most to only a few months (weeks?) of the year.

So what would you buy now and why?

Note that my main bike runs discs, as its a commuter and its greater in the wet and damp. Its also means I don't need to clean the gunk off the rims and aesthetically I like not having a brake track. The summer bike (sans chain currently) has rim brakes but that's because its old and to be honest don't mind whether it had discs or rim brakes.

mercalia
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Re: Disc v Rim brakes

Postby mercalia » 19 Aug 2016, 10:56am

samsbike wrote:I have summarised the arguments below but I still can't figure out if rim brakes are a better bet and why.

Note that I am not discussing touring here, where parts availability is crucial.

Disc brakes
Pro

2. can run different tire sizes depending on bike - if that's your thing





eh?

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Spinners
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Re: Disc v Rim brakes

Postby Spinners » 19 Aug 2016, 10:58am

I can totally agree with Point 1 - Pro and Con!

The first time I used disc brakes in anger was a revelation. Some old git came into a mini-roundabout from the left initially without seeing me, then he did see me so did an emergency stop. On my rim brake bike I would have been over the bonnet but I came to a controlled straight-line stop with my front wheel just under his front wheel arch. I was really impressed! Less so with his driving :roll:

However, I have to admit that the ride is harsher. This didn't bother me on shorter rides but did on a couple of longer rides. Perhaps people get used to it but I didn't get the chance to stick with it after trashing the rear wheel (my fault) and parking it up. This bike is currently in the shed awaiting parts but I will give it another go - perhaps over the winter months.
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Si
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Re: Disc v Rim brakes

Postby Si » 19 Aug 2016, 11:05am

Unless you say exactly what you'll be using the bike for it's pretty hard to answer the question. F'risntance, for an MTBer who lives in a very rainy, muddy area discs have a lot more pluses than someone rides time trials on quiet country roads.

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horizon
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Re: Disc v Rim brakes

Postby horizon » 19 Aug 2016, 11:14am

samsbike: this question has been done to death on this forum. FWIW, my own take on it is that V brakes are so adequate and so simple and so cheap and so common that complicating things with hydraulic fluid (if you use hydraulic discs) and God knows what on a practical bike seems madness.

But I would never claim that rim brakes are more effective and there are plenty of people who manage quite well thank you to maintain them. I suspect that there might one day be quite a few bikes lying around in their owners' garages awaiting disc brake servicing but that's pure speculation on my part.
I have two doctors, my left leg and my right leg. (G. M. Trevelyan)
PS I always wondered why the YHA HQ was called Trevelyan House. :)

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gaz
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Re: Disc v Rim brakes

Postby gaz » 19 Aug 2016, 11:50am

samsbike wrote:So what would you buy now and why?

For my own use I'd be buying a bike/frame for use with cantilever/V rim brakes.

The main reason is that they stop me to my complete satisfaction.

Additionally I understand these systems well, I can service and maintain them and I have spares already. In an emergency I can swop same size wheels between bikes without a second thought.

For me a change to discs would mean learning new skills, buying new spares and introducing incompatibility.

Maybe one day.
Hand wash only. Do not iron.

Dave W
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Re: Disc v Rim brakes

Postby Dave W » 19 Aug 2016, 12:12pm

New skills :?
Harsher ride?
I have two very similar bikes one with discs the other with rim brakes both made from the same materials they both ride much the same. One stops better than the other.
That's the only difference.

blackbike
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Re: Disc v Rim brakes

Postby blackbike » 19 Aug 2016, 12:39pm

Bad braking is something I remember from when I had tourers with Shimano or Avid cantilever brakes. They were poor, despite some people claiming that they are wonderful if set up right.

I fitted my tourers with dual caliper front brakes. My road bikes always had dual caliper brakes, as is still the norm.

Just as I ditched cantilevers because they are rubbish, I'd change the brakes on my ageing fleet of bikes, or even buy new bikes, if I thought a better alternative was available.

However, my experience of disc brakes on borrowed bikes has led me to believe that there is little if any improvement in braking over dual calipers, or the V brakes on my old MTBs, and so they are not worth the expense, complexity and compatibility problems of swapping wheels between bikes.

I think their main usefulness on road going bikes is that they are regarded as trendy and high tech, just like superfluous suspension is, and needlessly different frame shapes.

If these things encourage the fashion conscious consumer to try cycling then that is a good thing.

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horizon
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Re: Disc v Rim brakes

Postby horizon » 19 Aug 2016, 12:42pm

Dave W wrote:New skills :?


Not at all. But here's some bedtime reading:

http://www.epicbleedsolutions.com/blog/ ... neral-oil/

The bits I like are:

"Eats paintwork and irritates the skin - you don't want this stuff in your eyes." (DOT fluid) and

"Another great thing about Mineral Oil is that it does not destroy your paintwork, something which is very important as bikes and bike gear gets shinier by the week. Don't blemish that bling now!"

But then:

"A huge disadvantage of Mineral Oil, or proprietary brake fluid, is the cost. As it is one-of-a-kind, there's no competition (as such) and the warranty says you should use it, they can basically charge what they like for it - and they do. Not cool!"

I'm still for V brakes but that's just my preference and your mileage may vary. My guess is that brake servicing is now for many people either not done or it's a bike shop job.
I have two doctors, my left leg and my right leg. (G. M. Trevelyan)
PS I always wondered why the YHA HQ was called Trevelyan House. :)

matlockmark
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Re: Disc v Rim brakes

Postby matlockmark » 19 Aug 2016, 12:56pm

For me there is one overwhelming advantage: the elimination of wheel rim wear.

I live on a long steep hill; every ride starts with about half a mile of descent at gradients up to 30%. My everyday bike once got through a set of rims in just over 4 months. This was after recently finally wearing out a set of mavic ceramic rims, that had lasted nearly 10 years. As these are no longer available, and have certain disadvantages anyway, I decided to buy a bike with disk brakes. So far this has performed well, brake disks and pads are easier for me to replace than wheel rims.

In addition there is no chance of tyre blowout due to overheating, or due to wear making the rim walls too thin to hold the tyre pressure.

Bmblbzzz
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Re: Disc v Rim brakes

Postby Bmblbzzz » 19 Aug 2016, 1:09pm

I was about to point out the same as matlockmark above, the OP has missed out one of the big pluses of disc brakes.

Dave W
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Re: Disc v Rim brakes

Postby Dave W » 19 Aug 2016, 1:10pm

Why worry what flavour your brake fluid is? When the time comes to bleed then my local bike shop will do it for me. I don't care what fluid they use just as long as it all works as it should.

Bmblbzzz
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Re: Disc v Rim brakes

Postby Bmblbzzz » 19 Aug 2016, 1:12pm

mercalia wrote:
samsbike wrote:I have summarised the arguments below but I still can't figure out if rim brakes are a better bet and why.

Note that I am not discussing touring here, where parts availability is crucial.

Disc brakes
Pro

2. can run different tire sizes depending on bike - if that's your thing





eh?

I think what samsbike means is different rim sizes (and therefore different tyre sizes). As the rim is no longer needed for braking, it doesn't have to match up with the brake calipers or posts, so you can have eg a 700c with a narrow tyre for faster days and a 26" wheel with a fat tyre for days when you want to ride off-road.

geocycle
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Re: Disc v Rim brakes

Postby geocycle » 19 Aug 2016, 1:20pm

Bmblbzzz wrote:I was about to point out the same as matlockmark above, the OP has missed out one of the big pluses of disc brakes.


Yes, that could be an advantage and should be on the list. I'd rather trust my rohloff wheel rebuilds to SJS rather than my LBS or DIY but it does mean I'm without it for a week with the postage. For that reason disks could have been helpful. That said, I have got 20,000 miles out of a rigida grizzly CSS rim and its still not worn through so with careful rim choice it is not a frequent problem.

samsbike
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Re: Disc v Rim brakes

Postby samsbike » 19 Aug 2016, 1:33pm

Bmblbzzz wrote:
mercalia wrote:
samsbike wrote:I have summarised the arguments below but I still can't figure out if rim brakes are a better bet and why.

Note that I am not discussing touring here, where parts availability is crucial.

Disc brakes
Pro

2. can run different tire sizes depending on bike - if that's your thing





eh?

I think what samsbike means is different rim sizes (and therefore different tyre sizes). As the rim is no longer needed for braking, it doesn't have to match up with the brake calipers or posts, so you can have eg a 700c with a narrow tyre for faster days and a 26" wheel with a fat tyre for days when you want to ride off-road.



Got in one!

I dont need a new bike but one day I want to get one. My uses will be commuting and riding for a day. I dont envisage carrying anything heavy, its just something nimble and fun. But I still can't get my head around it.

My mtb has disc brakes and I have not thought about them once. It was converted for road use (guards and slicks) but was still quite ponderous ride (although its no heavier than my commuter).