totalnewbie

I have heard that with the power of disc brakes, they are an overkill for folders with smaller wheels (16"/20" etc) anyone with practical experience? If rim brakes are more than sufficient for folders in dry condition, what about wet condition?

GTA

Some say so, but from my point of view, in the end, braking is all about momentum and grip.
If you can handle disc brakes well on your "bigger wheel" bikes, then I don't see any infeasibility to put them on a smaller bike.

Pinigis 

There are several advantages to disc brakes over traditional rim brakes. For one they concentrate the braking forces at the axle so stability is improved. Additionally, they work well in all weather conditions. They don’t care if the discs are wet or dry. They also require less maintenance because they tend not to come out of adjustment as easily as rim brakes do.

Schwinnsta

Please explain this to me. Why does concentrating braking forces at the axel improve stability?

cat0020

Brakes, who needs them, they only slow you down.
I've been riding my 20" Sundeal mechanical disc brake folding bike for over 3 years.
The rotors are 140mm, calipers are cheap, cable actuated, brake pads are generic, not grabby.
They offer plenty of braking force for my commute riding in NYC metro, among motor vehicle traffic.
Few times that I have locked up the rear wheel due to slippery surfaces in winter time, snow or ice accumulation.
Beyond that, with 20 x 1.5 tires, they seem to work fine for me, less adjustment to the brakes when the wheels are out of true.
Hydraulic brakes, however, IMO they are overkill for smaller wheels.

Pinigis 

From Orbeca, "Because of their safety, effectiveness, power, modulation, maintenance, ride, comfort, confidence and once again, safety, the disc brake system far exceeds the traditional rim brake system."

From ericsbikeshop.com, "Disc brakes, on the other hand, apply pressure to a rotor at the center of the wheel at the hub. This brings about three primary riding advantages. Most importantly, disc brakes give you better braking control versus rim brakes. They allow you to stop more quickly, accurately, with control, and at the speed you want in a variety of conditions."

From CyclingWeekly, "The advantages of disc brakes, with their improved control and reliability show the system certainly has its appeals."

Maybe stability wasn't the best word, control may be better.

tds101 

This is a fact. Disc brakes are perfect for a small wheel bike. Hydraulic though, NOPE!

I don't know why some people always argue against a small wheeled bike with disc brakes. They're so much easier for me to adjust than v/caliper/etc brakes. And never an issue in the rain

Schwinnsta

I agree that overall disks brakes are better and would not argue otherwise, the fact that they concentrate the force nearer the axle is one of their few negatives.

Ozonation

All that being said, I've not had much luck trying to finesse my bikes that do have disc brakes so that the rotor doesn't rub, is centered, etc. l prefer rim brakes overall because they seem simpler and cheaper to me, and I had no end to trouble once when i accidentally bent a rotor. I've also heard that packing a disc brake bike is fussy and more challenging if you have to remove the tires for packing.

Any great guides on adjusting disc brakes? I've look up a variety of videos, online tutorials, and even had a bike shop mechanic give me some tips, but my results have been mixed at best.

Pinigis 

How is this a negative?

Pinigis 

I will agree that packing a bike with disc brakes (assuming that you must remove the wheels to pack) is more difficult because you have to be more careful with the positioning of the wheels. But, I have traveled many times with my Origami Dragon in a suitcase with no issues.

Pinigis 

After you have adjusted a few hundred of them, it gets easier. It really depends upon the brakes. Hydraulic discs, and mechanical ones where both pads move, are super easy to adjust.

The more common mechanical disc calipers, where only one pad moves, take longer. With these, I turn the inside pad until it is touching the rotor and I have a small gap at the outside pad, then tighten the caliper in place. Then turn the inside pad out to create a gap and you are done.

Nyah

They may not be overkill for folding bicycles, but they are stupid. The problem with disc brakes on folding bicycles is that folding bicycles are usually OEMed as cheaply as possible, which currently amounts to badly-implemented disc brakes. Until folding bicycle frames/forks start being designed with thru-axles, I will ignore any that offer disc brakes. V-brakes stop just as well in dry conditions and are way more trouble-free than quick-release-based disc brakes. After you own a bicycle with thru-axles, the problem that's inherent to QR-disc can't be more obvious.

Ozonation

I'm pretty handy, but I have a ways to go for several hundred times! I wasn't aware that for the more common disc brakes, only one pad moves. I assumed both moved. I'll check that out. That understanding may help. Thanks.

Schwinnsta

You have to design stiffer forks, particularly the front fork. The stiffer forks transmit more impacts and vibration. Also, you can't put the forward bend in to achieve the rake. You can still get the rake, but by putting in that bend near the end of the fork, you get some bending and more vertical compliance, i.e. transmit less shock and vibration. Jan Heine explains this better than I can.

Tourist in MSN

I built up my Lynskey (full size bike, not folder) with rim brake on front and disc on rear. Front is V brake with a Travel Agent to convert road lever cable pull to mountain bike V brakes, Koolstop Salmon pads. Rear is TRP Spyre with full length compressionless housing.

In dry conditions, I can't tell the difference between the braking power on the front and rear.

In wet conditions, the disc is much more effective than the rim brake.

The rest of my bikes all have rim brakes that I am content with.

Exception, I have a 60s vintage three speed bike that has drum brakes that I occasionally take to the grocery store. Those brakes are not very good.

If you are content with the rim brakes on your folder in the conditions that you typically ride in, keep it.

Doc_Wui

For hydraulic brakes, both pads move, and all I do to align them is (a) loosen the two mounting screws (b) squeeze brake lever to center the mechanism on the rotor, and (c) retighten the screws. There's no cable tension to set. The feel of the lever is crisp/sure, no cable slop. I have hydraulic cable brakes on my larger bikes, and really like them.

I do prefer disk brakes in general for ease of removing the wheel. My 20" Sundeal minivello has cable operated disks, but has never had a flat tire, but our 20" folders are all v-brakes.

pinholecam

From my own experience with rim and mechanical disc brakes.

It all depends on the use condition.
The only time I feel that disc brakes are an advantage is with long steep mountain descents.
The modulation is better and less likely to 'arm freeze' gripping the brake levers too tightly that it compromises steering.

I ride in the rain/wet and over here in the center of the Equator, it rains every day or other day, so wet riding is hard to avoid.
Never found rim brakes to be inadequate in the rain/ wet.

I find rim brakes easy to service and adjust.
Mechanical disc brakes with 2 actuating brake surfaces are still ok to adjust, but less margin of error.
Too big a pad to disc gap and brake lever feels whimpy; Too close a gap and there is chance of rub.
Hydraulic will make it worse since it 'auto' adjusts that gap, so if you end up with brake rub in the field, its a very painful process to solve it (esp. over here where it usually means being in the 35-38degC Sun with RH of 85% or more )

Being able to use many tire sizes is a big plus for disc brakes.

IMHO, I'd just buy a bike if I like it and the type of brake is a non-consideration

cat0020

One advantage to disc wheels, the rim being out of true is not so much of a reason to stop riding, brakes do not rub against the rim.
You can limp home and adjust the spokes at a later time.

Jipe

Sounds like if you had SRAM or AVID hydraulic disc brakes!

I had AVID Code R and AVID Code 4 piston hydraulic disc brakes with exactly that problem and even worse: when it rubs and continue to ride, the disc eventually completely block the wheel and the bike become unusable until it cools down allowing to ride a little further... until it blocks again... I read feedback of other users with other models of AVID and SRAM hydraulic disc brakes who had exactly the same problem.
Its a design error, the liquid expand when it become warmer, there must be a return path to the handle liquid reservoir but it doesn't seem to work

I never had it with Shimano (XT and Deore) and Magura (old Marta SL and current MT5).

I have disc brakes on my two Birdy, and they are surely not overkill, TRP Spyre on one (mechanical 2 piston) and Deore (hydraulic 2 piston) on the other, the hydraulic are more progressive and require much less effort on the lever for the same braking.

tcs

It's no big deal in the great scheme of things, but kudos to everyone who spelled 'disc brake' correctly!

Yep! IIRC only Birdy's lowest cost model is still fitted with rim brakes; all the other models are fitted with F/R discs. Of course, all Stridas had discs for the last 15 years or so. Disc brakes on small wheel bikes are not exactly breaking news. So long as the brake has smooth, progressive modulation, well, why not?

Fun fact: Dahon recently teased the possibility of a future Curl model with disc brakes.

Pinigis 

Did you mean "braking news"**********

tcs

Disc breaks:

bee-man

I wish my Brompton had disc brakes because I have a steep descent (~ 1/2 mile) on my commute that I am able to reach speeds up to 30mph rolling. When it's wet/damp, I'm on the brakes the entire time and the rims get quite toasty. Also, I don't like the fact that the dirt and grime is just wearing the rim/brakes when the water kicks up. I'd rather replace rotors/pads than rims.

jackyharuhiko

My Birdy 3 is equipped with Avid disc brakes and I upgraded it to Shimano XT 2 piston hydraulic brakes recently. I find it much better when I’m descending from steep slopes, it feels much safer, and the effort to slow down or stop the bike is minimal.