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[Brompton] Brazing disk brake mount on front fork?

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[Brompton] Brazing disk brake mount on front fork?

Old 06-22-23, 10:02 PM
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[Brompton] Brazing disk brake mount on front fork?

Hello,

Since I use my Brompton for touring, ie. it's heavy, I could use stronger brakes, at least in the front where most of the weight moves when braking.

What are your thoughts about asking a frame maker to try and braze a disk brake mount on a third-party fork (to play it safe), and should it be on the left as usual, or on the right in case it'd interfer with folding?

Provided it's not a crazy idea, what about the brakes: Would an Avid BB7 mechanical brake + compressionless housing do, or should I consider TRP Hy/Rd hybrid brakes?

Thank you.

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Old 06-23-23, 02:04 AM
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TRP spyre is a better option than bb7.
I cannot see why you would hydro or hybrid (heavy) but if you do, juin tech calipers and TRP are good.
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Old 06-23-23, 05:37 AM
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I always liked the stock brakes on the Brompton. Very good, imo.
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Old 06-23-23, 06:26 AM
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I would not mount disc brakes on a fork that was not designed for braking forces in the lower reach. There are plenty of examples on the web of non-disc forks buckling after disc brakes have been welded. I would buy a brompton fork designed for discs.
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Old 06-23-23, 07:29 AM
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Originally Posted by Schwinnsta
I always liked the stock brakes on the Brompton. Very good, imo.
In steep descents with a total weight of ~30kg/67lbs, I wish I had stronger brakes.

Incidentally, has someone tried Litepro's Brompton calipers?

https://bromptuning.com/en/products/...-bc1-remhoeven

Last edited by Winfried; 06-23-23 at 01:35 PM.
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Old 06-24-23, 12:19 AM
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What hubs would you use? Itís my understanding that Bromptons like most rim-braked small-wheeled folding bikes use 74mm wide front hubs, which are only easily available without the mountings for a brake disc.

Kinesis in Scotland makes forks and rear triangles for Bromptons that are designed for disc brakes. Have a look.
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Old 06-24-23, 02:16 AM
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I know Kinetics, but it's a lot more expensive than just brazing a mount on a regular steel fork.


https://www.aliexpress.com/item/1005003842886111.html
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Old 06-24-23, 02:44 AM
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Originally Posted by BobbyG
I would not mount disc brakes on a fork that was not designed for braking forces in the lower reach. There are plenty of examples on the web of non-disc forks buckling after disc brakes have been welded. I would buy a brompton fork designed for discs.
Don't say you haven't been warned. There's a reason forks built for disc brakes weigh more and cost more than forks for rim brakes.

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Old 06-24-23, 03:26 AM
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Its definitely not a good idea to add a disc mounting on a fork no designed for disc braking since the effort on the fork are very different with rim and disc brakes.

But I agree that the stock brakes of the Brompton, even the latest one, are poor due to a lack of rigidity of the levers and calipers.

The easiest upgrade is to mount Ridea brake levers and calipers designed for Brompton, they re much better and provide a much better braking.

Another option is to use eebrakes calipers that are the best rim brae calipers on the market providing the best braking when coupled with good levers but the mounting is less straightforward, you need some additional parts to have a cable output bottom left.
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Old 06-24-23, 03:14 PM
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There comes a point when...

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Old 07-01-23, 05:41 AM
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On a Brompton where your front tire is on the ground further aft from where it would be on a full size 700c bike, that increases the chance that hard braking could cause you to go over the handlebars as the rear wheel lifts off the ground. Steep downhill where your center of gravity is further forward compared to where your front tire is on the ground, that increases the chance even more.

You said for touring, if you have panniers on the rear rack that shifts bike center of gravity further aft, making it less likely that this would be a problem, but I have seen plenty of Brompton photos showing a large bag on the bike in front of the head tube, which shifts center of gravity further forwards, which could make this more likely.

I was doing maybe 15 miles an hour on a full size bike when the moron in the lane next to me very suddenly decided that she wanted my lane and she decided I was not there. I hit the brakes hard and went over the handlebars. Not fun.
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Old 07-01-23, 09:35 AM
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Have better quality brake pads been considered? Are disc brakes lighter than calipers?
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Old 07-01-23, 11:23 AM
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To minimize the folded silhouette, the Brompton orients its brake levers straight down from the handgrips.



A no-cost brake improvement modification is to orient the levers in a more ergonomic position, like other bikes:

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Old 07-01-23, 12:16 PM
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Originally Posted by Tourist in MSN
On a Brompton... Not fun.
Because of weight, center of gravity, geometry, costs and other considerations, it's pretty much impossible to design idiot-proof bicycle brakes.




I have an old utility bike in the garage factory-equipped with a 'Shimano Power Modulator' on the front V-brake. This is a small spring-loaded device that prevents enough cable travel from reaching the brake arms to clamp down the front brake, making 'over the bars' impossible. Load that bike up with touring dunnage and head down an Alpine pass in the rain? No, thank you.

The late John Forester's much-derided Effective Cyclist training covered maximum braking in an effort to compensate for the inherent nature of cycles with increased between-the-ears knowledge/skill.


Last edited by tcs; 07-01-23 at 01:15 PM.
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Old 07-01-23, 12:42 PM
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Considering it’s price, I would think Brompton would have better brakes.
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Old 07-01-23, 02:28 PM
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Brompton does have good brakes. The problem is that for mountain descents with touring weights, the rims heat up and that can lead to problems. If you can already lock up your front tire, what more could you ask? I suppose disk brakes, but then for only that limited case
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Old 07-01-23, 05:49 PM
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Mountain descents, I have stopped part way down and felt my rims to see how hot they are. And there have been a few times when I decided to sit on the side of the road for 5 or 10 minutes for my rims to cool. That was with a full size bike, not small wheels.

I have not ridden a small wheel folder down a mountain descent but I would assume that a smaller rim that rotates faster would mean there is a lot less rim to heat up, likely would heat up faster than on a 700c bike.

But touring, it is not a race, take your time and be safe.
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Old 07-01-23, 07:34 PM
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Originally Posted by Tourist in MSN
...

I have not ridden a small wheel folder down a mountain descent but I would assume that a smaller rim that rotates faster would mean there is a lot less rim to heat up, likely would heat up faster than on a 700c bike.

...
I have. Many times. On ISO305 wheels. And yes, they can heat up pretty quickly due to the reduced surface area. Here proper technique is crucial. Don't ride the brakes. Stand up so your body becomes a sail and creates a bigger aerodynamic profile and drag. Stop and check. Douse with water when needed.



Descent from 1,300masl
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Old 07-01-23, 07:51 PM
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Fortunately, this descent at 14 percent was not very tall, rims did not heat up. Sorry, not a folder in the photo.

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Old 07-01-23, 08:43 PM
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Originally Posted by tcs
Because of weight, center of gravity, geometry, costs and other considerations, it's pretty much impossible to design idiot-proof bicycle brakes.

Nice "stoppie"!
Fortunately, the center of gravity of the cycle/rider unit is not fixed. A useful skill to develop is moving the rider's butt as far back as possible. This markedly increases the amount of braking force that can be applied before the rear wheel lifts.
That brake "Power Modulator" scares the crap out of me... I would never intentionally limit the braking force if a simple change in rider position would solve the problem.
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Old 07-02-23, 06:07 AM
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If you can already lock up your front tire, what more could you ask?
Linear modulation through a large (but ergonomic) brake lever travel arc. Large enough heat energy sink without fading or damage.

Last edited by tcs; 07-02-23 at 08:34 AM.
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Old 07-17-23, 08:29 PM
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Nope. If you want to improve your front braking, you can do a number of things short of damaging your front fork by brazing on a disk brake mount. Better pads can improve braking, and are cheap. The next step are higher quality calipers, which are usually lighter and are more rigid, and, last, better brake levers. The original Brompton brake levers are pretty awful. I use Avid SL levers with the “speed dials.” These are made of magnesium and are super light, and speed dials allow you to increase or decrease the leverage applied to the brakes for the same amount of hand pressure on the lever itself. Set up properly, on a true wheel you get great stopping performance and modulation.
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Old 07-18-23, 03:35 AM
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Good to know they fit Bromptons. I'll get a pair.

What about compressionless brake housing? Do they make a real difference?

--
Edit: How would they compare to Shimano's Claris BL-R2000? Also, the Avid are meant for "linear-pull brakes", ie. v-brakes while Bromptons use road calipers.




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Old 07-18-23, 06:12 AM
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Changing the levers and calipers for others isn't that easy.

First, the Brompton levers put the cable housing tilted wrt. the handlebar to prevent then to hit a front bag. Most levers put the cable housing parallel to the handlebar. And the levers should be designed for road calipers, not V-brake or MTB mechanical disc calipers.

Second, the Brompton brake calipers have their cable+housing output bottom left instead of top right like most road calipers. And to have space for 35mm wide tires+mudguards, they must be long reach, not short reach like most road brake caliper.

There are few road brake calipers fully compatible. The best ones are the designed for Brompton Ridea brake calipers they have much better performances and weight less. Ridea has also Brompton compatible brake levers.
But both are quite expensive and not very easy to buy for people in Europe or US.

For the brake calipers, its also possible to mount the best in class Cane Creek eebrakes but with some modification to have their cable output bottom left + an adapter to place them lower (Ti Parts Workshop has special parts for that). Do not use the for eebrake long reach caliper arms proposed by some third parties as they destroy the best in class braking performances of the eebrakes.

Note that depending of the model year, the mounting of the brake calipers on the Brompton is different, on older Brompton its a classic nylstop nut, on the more recent one its a recessed nut.
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Old 07-18-23, 06:45 AM
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What about just changing for those levers (Avid, Shimano) while keeping the dual pivot Brompton calipers? Is it worth it?

--
Edit:
Q.Do [Avid Speed Dial 7 levers] work with road calipers?
A. They will not, the Avid Speed Dial 7 levers are compatible with long pull brakes, road caliper brakes are short pull.
(Source)

Shimano Claris BL-R2000 : "Dual-Pivot Brake Lever for Cantilever Brake, Caliper (new SUPER SLR), Mechanical Disc Brake, V-BRAKE - Clamp Band - Flat Bar Road"

Last edited by Winfried; 07-18-23 at 08:04 AM.
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