Upon sharing my thoughts in an answer to a Bicycle Stack Exchange question, I wondered about my suggestion to use a disc brake up front on a frame that, lacking a disc brake caliper mounting point at the rear and thus implying a lack of additional design considerations for disc brake usage in either the front or rear. I've a lifetime bicycle tinkering experience, and I know I've heard of running a front disc brake though I can't remember actually seeing this setup. So, given a bicycle, designed and marketed as a "mountain bike" but lacking a disc brake mounting point on the frame and also equipped with an after market, yet otherwise compatible, suspension fork which has both disc and rim brake mounts: would it be safe to run a disc brake (and rim, of course) in the front of this bike? If not, why? Any considerations as to safety or viability between the two types of disc systems, hydraulic or cable-mechanical? (Above and beyond the lever, including the ability to use matching front and rear levers in a mechanical disc + v-brake set up).
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2For the frame it doesn’t make any difference. The same forces act on the steering tube.– MichaelCommented Oct 23, 2019 at 7:28
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There's no harm in trying this setup other than costs. If you don't like it then revert.– Criggie ♦Commented Oct 23, 2019 at 7:49
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3It makes a lot of sense to have the better brake in the front. The fork needs to be able to take the maximum braking force and then some anyway.– Peter - Reinstate MonicaCommented Oct 23, 2019 at 13:14
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3We call this the mullet where I am - business in the front; party in the back. I've run this setup with no issues.– ankh-morporkCommented Oct 23, 2019 at 13:50
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@ankh-morpork +1 & Lol. I was a teenager thru much of the 80's and sported a mullet several times. Hasn't returned since '92. Thanks for ur input– JeffCommented Oct 24, 2019 at 0:31
3 Answers
A few years ago this was a reasonably common setup as sold. I've certainly ridden an e-bike set up that way, with v-brakes at the back and a mechanical disc brake at the front. I suspect this wasn't so much about stopping power as not needing maintenance between services, though in practice some adjustment was required even if less than at the back.
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1My hybrid is capable of the opposite - it has disc mounts on the frame, but not the fork (I bought the cheaper of 2 options but the frame was common to both)– Chris HCommented Oct 23, 2019 at 6:01
I ran this setup for a while on a Kona Stuff. In fact, it came like that from the Factory as I had the fork upgrade option to Fox32 with hydraulic disc, but the rear was still V-Brake. It was fine.
Mechanically i cant see any issues with this, however...
Disk brakes, especially hydraulic, require significantly less force on the lever compared to rim brakes so if you find yourself pulling both lever just as hard you may find yourself going over the bars.
You may be able to mitigate this will a longer lever for the rim brake and a shorter lever on the Disk/hydraulic brake.
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1This is a matter of somehow "tuning" the "mechanical advantage" of the two levers so that they match. Commented Oct 23, 2019 at 2:32
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@Rhys Good point, thanks. I typically have the front v-brake fairly tight (pads close and short lever pull). That, and by virtue of being in the front, the stopping power per mm of lever pull is much greater on my left so I'm used to differing brake feels. Your point is definitely worth discussing with someone who may want to try doing this.– JeffCommented Oct 23, 2019 at 4:40
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A mechanical disc brake would be far easier to balance than hydraulic brakes , you could simple adjust the movement at the pad end to to roughly the same as the rear rim brake– Dan KCommented Oct 23, 2019 at 5:23
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8But pulling both levers with equal force isn't ideal braking behaviour anyway in most circumstances. With equal brakes it's a recipe for skidding the back whenever you brake hard, which isn't usually too bad, and for skidding the front on loose surfaces, which can be.– Chris HCommented Oct 23, 2019 at 6:06
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...you may find yourself going over the bars.Especially if it's a mountain bike... going down a mountain.– J...Commented Oct 23, 2019 at 12:09