Disc brake AND rim brake?

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MiddMan
Posts: 167
Joined: Sun Jun 07, 2015 4:54 pm

by MiddMan

I have never used disc brakes, nor am I in the field of engineering, mechanics, etc., so this is an honest question: has anyone tried, or is it even possible, to run one disc brake and one rim brake?

For example: disc on rear and rim on front. I realise this would require a unique set up including: a) a bike with disc compatible rear and rim compatibilie fork, b) two unique wheels, c) perhaps two separate levers. And d) the 'feel' of the braking would also probably be different. But, unless I am missing something here, it would seem to be a good compromise:

The front wouldn't look so ugly, nor would there be a sacrifice in aerodynamics. It would also be lighter. The back already has the cassette, so the disc 'blends in' so to speak, and there's probably little to no aero penalty. Yet it would give extra/safer stopping power on the steeps when using carbon wheels.

Given what I've already mentioned, what would be other pros and cons (or impractical/impossibilities) to such a set up?

by Weenie


MiddMan
Posts: 167
Joined: Sun Jun 07, 2015 4:54 pm

by MiddMan

FWIW I have no intention in trying this, I'm merely curious!

glam2deaf
Posts: 702
Joined: Mon Apr 27, 2015 4:36 am

by glam2deaf

It's been done the other way around, though there are practical reasons why.
Image

Though seriously, I don't really see the point. Aside from looking weird, all the mis-matched parts you're going to end up with and the effort required just doesn't seem worth it.
Last edited by glam2deaf on Thu Jul 06, 2017 3:42 am, edited 1 time in total.

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silvalis
Posts: 469
Joined: Mon Sep 07, 2015 1:02 am
Location: Aus

by silvalis

I reckon it would be more practical to have a disc front and rim rear...
Chasse patate

jlok
Posts: 675
Joined: Tue Jun 30, 2015 3:30 am

by jlok

I think one could easily fit a disc brake fork to rim brake frame.

The question would be the value of doing it. If you want disc brake because of the safety concern with carbon rim braking, you better go full disc brake rather than buying a disc brake fork.
Giant Propel Advanced SL Disc 1 < Propel Adv < TCR Adv SL Disc < KTM Revelator Sky < CAAD 12 Disc < Domane S Disc < Alize < CAAD 10

dmulligan
Posts: 313
Joined: Wed Jul 23, 2014 6:16 pm

by dmulligan

I've often thought about putting a disc brake fork on my cross commuter bike because cantilever brakes suck. I think that my Tiagra 4400 brifters would be compatible with a cable actuated disc brake so the number of parts needed would be minimal. It also allows me to keep the rear wheel compatible with the rest of my stable.

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alcatraz
Posts: 1234
Joined: Mon Aug 29, 2016 11:19 am

by alcatraz

I've been thinking about such an upgrade. I'm happy with my current bike in almost all aspects and don't wan't to change it really. Only braking is not up to par...

A fix would be to get a disc brake fork and do a mechanical setup. That way I don't have to worry so much while descending.

On a motorcycle they say braking performance is like 90/10 front/back. On a bike its more even but the front wheel is going to take up most of it.

Doing it on the rear sounds like a backward idea to me though. You're trying to improve a place where braking is already limited.

/a

jlok
Posts: 675
Joined: Tue Jun 30, 2015 3:30 am

by jlok

alcatraz wrote:Doing it on the rear sounds like a backward idea to me though. You're trying to improve a place where braking is already limited.

/a

Not if...
1. you have carbon rear wheel, and
2. you ride in wet days (or it suddenly rains and you keep riding)

it hurts to brake with rim brake when it's wet... the dirt paste accumulated on the pads will be like sand paper scratching your precious rim...
Giant Propel Advanced SL Disc 1 < Propel Adv < TCR Adv SL Disc < KTM Revelator Sky < CAAD 12 Disc < Domane S Disc < Alize < CAAD 10

mattr
Posts: 3755
Joined: Fri May 25, 2007 6:43 pm
Location: The Grim North.

by mattr

MiddMan wrote:But, unless I am missing something here, it would seem to be a good compromise:
Nope, bad compromise, disc should be on the front where ~75% of the braking load can be applied. Disc on the rear is only any good for specific types of bike. i.e. bikes with no facility for a front brake (jump bikes?) or possibly delivery bikes, or those towing trailers or significant loads over the rear wheel.

MiddMan wrote:Yet it would give extra/safer stopping power on the steeps when using carbon wheels.
On the steeps you'd get even less braking as the weight shift to the front wheel would be greater and quicker. As you will already be shifted slightly forwards

MiddMan wrote:Given what I've already mentioned, what would be other pros and cons (or impractical/impossibilities) to such a set up?
Cons 1) Not able to stop effectively. 2) Have to replace your frame (expensive)
Pros 1) can do massive skids

Just buy a new fork and stick a disk on the front. Pretty sure you can still get disc hubs with rim brake rims. So you can even use the same wheels.
My wifes MTB was set up like this for ~10 years. BB5 on the front XTR V on the back some mavic Cross ride wheels. The wheels were still in very good condition (rear really doesn't get much wear unless you ride in *really* crap conditions and never clean the pads/rims.)

mattr
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Joined: Fri May 25, 2007 6:43 pm
Location: The Grim North.

by mattr

glam2deaf wrote:Though seriously, I don't really see the point. Aside from looking weird, all the mis-matched parts you're going to end up with and the effort required just doesn't seem worth it.
Most road frames come with no disc mounts, so this is an easy way to get good commuter/wet weather performance without splashing out on a new frame. Should cost around €300 for mech discs and "commuter" level kit (road)

Multebear
Posts: 1148
Joined: Sat May 02, 2015 10:11 pm

by Multebear

Kinsesis 4S disc has option for both disc and rim brake both front and rear. Might be good to do you experiment on.

http://www.kinesisbikes.co.uk/Catalogue ... ht/4S-DISC

pdlpsher1
Posts: 1687
Joined: Thu Jul 19, 2012 6:09 pm
Location: CO

by pdlpsher1

This is a very common setup on tandems. A tandem has a wider rear dropout spacing hence the disk on the back is a no-brainer. The front brake isn't needed often and it's only used for emergency stops. One can pull on the rear disk brake lever really really hard and the rear tire will never lock up due to the extremely high coefficient of friction on a rear tandem tire.

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dmulligan
Posts: 313
Joined: Wed Jul 23, 2014 6:16 pm

by dmulligan

Someone else mentioned this but I forgot to mention too when I spoke of my ideas regarding a front disc brake... When I was more interested in making my Jake lighter and/or upgrading it I partially wanted the disc brake so I could have carbon clinchers without worries. Since then my Jake has been relegated to mainly commuter duty. However the rest of what I said is still true. Cantilever brakes suck and for that reason I'm still interested.

However one wheel mismatch I'm surprised I've never seen is a front carbon wheel with an aluminium brake track in the front and a full carbon wheel in the rear. I've always thought that combination would give be a good compromise between braking performance, safety and weight. Now I'm thinking that I need to build such a front wheel for my road bike...

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by Weenie


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