Go Back  Bike Forums > Bike Forums > Folding Bikes
Reload this Page >

[Brompton] Add disk brake to original fork?

Notices
Folding Bikes Discuss the unique features and issues of folding bikes. Also a great place to learn what folding bike will work best for your needs.

[Brompton] Add disk brake to original fork?

Old 06-01-18, 06:24 AM
  #1  
Winfried
Senior Member
Thread Starter
 
Winfried's Avatar
 
Join Date: Aug 2011
Location: Paris, France
Posts: 2,101
Mentioned: 9 Post(s)
Tagged: 0 Thread(s)
Quoted: 386 Post(s)
Liked 58 Times in 49 Posts
[Brompton] Add disk brake to original fork?

Hello,

I'm not technical but I could find someone who knows about welding/brazing/soldering.

Out of curiosity, what would it take to add a disk brake to the original fork? Do I just need to add a contraption on the fork to hold the disk caliper?

I'm interested in having a disk brake in the front, but €500 is a bit too much money.

Thank you.
Winfried is online now  
Old 06-01-18, 07:05 AM
  #2  
berlinonaut
Senior Member
 
Join Date: Mar 2016
Posts: 656
Mentioned: 13 Post(s)
Tagged: 0 Thread(s)
Quoted: 314 Post(s)
Liked 11 Times in 9 Posts
Originally Posted by Winfried View Post
what would it take to add a disk brake to the original fork?
Probably at first a wider original fork. currently the original needs a 74mm hub (vs. 100mm "usual" size) - when adding a disc brake it would to be even slimmer. Not sure if i.e. Dahon or Tern do have 74mm disc hubs. Other than that I would not be sure if the current original Brompton forks are suited well to fit the forces from disc brakes (that are different from those of rim brakes).
berlinonaut is offline  
Old 06-01-18, 12:40 PM
  #3  
rishardh
Senior Member
 
rishardh's Avatar
 
Join Date: Jun 2008
Location: North Texas
Posts: 429

Bikes: Kestrel Talon; Giant NRS Air; Litespeed Tuscany; Burley Rivazza; Cerverlo RS; BMC SLX01; Litespeed C1r, Merckx Corsa 01, Schwinn Traveller, Brompton M6L

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 23 Post(s)
Likes: 0
Liked 2 Times in 2 Posts
Looking at the Brompton fork shape I think it is designed to flex a little to soak in the bumps. This will not be ideal for disk brakes as the caliper will rub the rotor even if you manage to weld/braze a mount. I am not an expert and maybe it's doable if you are riding around town and not going down mountain passes. Road bikes without shocks have disk brakes now.
rishardh is offline  
Old 06-01-18, 01:55 PM
  #4  
Tourist in MSN
Senior Member
 
Join Date: Aug 2010
Location: Madison, WI
Posts: 8,037

Bikes: 1961 Ideor, 1994 Bridgestone MB-6, 2006 Airnimal Joey, 2009 Thorn Sherpa, 2013 Thorn Nomad MkII, 2015 VO Pass Hunter, 2017 Lynskey Backroad, 2017 Raleigh Gran Prix, Perfekt 3 Speed -age unknown, 1980s Bianchi Mixte on a trainer. Others are now gone.

Mentioned: 35 Post(s)
Tagged: 0 Thread(s)
Quoted: 2192 Post(s)
Likes: 0
Liked 468 Times in 384 Posts
A disc means that you have to have a much stronger fork blade to avoid bending it. A regular large wheel bike would have to have a much stronger fork than a small wheel bike, but still even on your small wheel bike you are risking damage to the bike and yourself if you try it.
Tourist in MSN is offline  
Old 06-01-18, 02:42 PM
  #5  
Winfried
Senior Member
Thread Starter
 
Winfried's Avatar
 
Join Date: Aug 2011
Location: Paris, France
Posts: 2,101
Mentioned: 9 Post(s)
Tagged: 0 Thread(s)
Quoted: 386 Post(s)
Liked 58 Times in 49 Posts
Thanks for the feedback.
Winfried is online now  
Old 06-02-18, 10:23 AM
  #6  
fietsbob
Banned
 
Join Date: Jun 2010
Location: NW,Oregon Coast
Posts: 43,599

Bikes: 8

Mentioned: 197 Post(s)
Tagged: 0 Thread(s)
Quoted: 7607 Post(s)
Liked 1,310 Times in 823 Posts
has to be 10cm wide too, not 7.4 , you need to buy Ben Cooper's upgrade frame parts .

get the set with an Alfine disc hub compatible rear end. too..

you can even use French-British rail via the Chunnel, get to Glasgow, in Person.




...
fietsbob is offline  
Old 10-24-19, 11:58 AM
  #7  
Winfried
Senior Member
Thread Starter
 
Winfried's Avatar
 
Join Date: Aug 2011
Location: Paris, France
Posts: 2,101
Mentioned: 9 Post(s)
Tagged: 0 Thread(s)
Quoted: 386 Post(s)
Liked 58 Times in 49 Posts
I notice there are 74mm disk hubs, and adapters are available to retrofit disk calipers on bikes with rim brakes.

Would a Brompton fork have to be significantly hardened to withstand a disk brake?

And to avoid increasing the depth of the bike while folded, what about installing the disk on the right instead?

Winfried is online now  
Old 10-24-19, 03:35 PM
  #8  
bee-man
Junior Member
 
Join Date: Apr 2006
Posts: 18
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 7 Post(s)
Likes: 0
Liked 3 Times in 3 Posts
Can't provide any input here, but just wanted to say that it would be nice to have at least one disk or the option for disk brakes. My first mile is a long descent and I don't particular like using calipers to slow down, especially when wet. My rims get quite toasty.
bee-man is offline  
Old 10-24-19, 04:23 PM
  #9  
Winfried
Senior Member
Thread Starter
 
Winfried's Avatar
 
Join Date: Aug 2011
Location: Paris, France
Posts: 2,101
Mentioned: 9 Post(s)
Tagged: 0 Thread(s)
Quoted: 386 Post(s)
Liked 58 Times in 49 Posts
If no one's done it and people shell out big buck$ for tailor-made forks from Kinetics, Eerder Metaal, et al., I guess it's either not doable or unsafe with the original fork.
Winfried is online now  
Old 03-28-21, 02:19 PM
  #10  
Winfried
Senior Member
Thread Starter
 
Winfried's Avatar
 
Join Date: Aug 2011
Location: Paris, France
Posts: 2,101
Mentioned: 9 Post(s)
Tagged: 0 Thread(s)
Quoted: 386 Post(s)
Liked 58 Times in 49 Posts
Incidently, several manufacturers* offer a front hub motor to turn a regular Brompton into an e-bike.

If the original fork is strong enough to withstand a hub motor with a torque of about 50Nm, wouldn't it be able to also take the force from a disk brake?

If all it takes is finding a competent LBS to weld a disk caliper adapter on the right side to fit the Brompton's folding, getting the kind of 74mm wide hub I mentioned above, and building a wheel… it'd be a nice upgrade.

Of is the effort from a disk brake very different from a hub motor?

* AKM-F, Crystalyte NSM/SAW20, Swytch, MkXR, Q70, etc.
Winfried is online now  
Old 03-28-21, 07:27 PM
  #11  
Schwinnsta
Schwinnasaur
 
Schwinnsta's Avatar
 
Join Date: Dec 2006
Location: New Orleans, LA
Posts: 1,123
Mentioned: 9 Post(s)
Tagged: 0 Thread(s)
Quoted: 240 Post(s)
Liked 24 Times in 18 Posts
Originally Posted by Winfried View Post
Incidently, several manufacturers* offer a front hub motor to turn a regular Brompton into an e-bike.

If the original fork is strong enough to withstand a hub motor with a torque of about 50Nm, wouldn't it be able to also take the force from a disk brake?

If all it takes is finding a competent LBS to weld a disk caliper adapter on the right side to fit the Brompton's folding, getting the kind of 74mm wide hub I mentioned above, and building a wheel… it'd be a nice upgrade.

Of is the effort from a disk brake very different from a hub motor?
Braking forces are much greater because the acceleration is much stronger. Your braking from speed in just a couple of seconds. That is a lot force. F=MA where A is the change of speed with time.
Schwinnsta is offline  
Likes For Schwinnsta:
Old 03-30-21, 12:07 PM
  #12  
Doc_Wui
Senior Member
 
Doc_Wui's Avatar
 
Join Date: Jul 2015
Location: Chicago Suburbs
Posts: 1,102

Bikes: GT Transeo & a half dozen ebike conversions.

Mentioned: 4 Post(s)
Tagged: 0 Thread(s)
Quoted: 258 Post(s)
Liked 75 Times in 59 Posts
You can buy a carbon fork with disk tabs and 74 mm dropout on aliexpress for $65, but I'd sooner have tabs welded onto a steel fork. Those adapters are pretty weak. I paid $3 for one and decided it was it really flimsy, and it only fits certain fork geometries. Some people just tack weld them to their forks and add a little reinforcement.

My Downtube (100mm suspension forks) has tabs for disks, but I would have to spoke a hub up to get rotor capability. I've found that in general, adding rotors/calipers to a bike that had good rim brakes is a wash at best. It's only good if you do a lot of wheel removal.
Doc_Wui is offline  
Old 03-30-21, 03:46 PM
  #13  
Winfried
Senior Member
Thread Starter
 
Winfried's Avatar
 
Join Date: Aug 2011
Location: Paris, France
Posts: 2,101
Mentioned: 9 Post(s)
Tagged: 0 Thread(s)
Quoted: 386 Post(s)
Liked 58 Times in 49 Posts
Are there standard forks that fit the Brompton?
Winfried is online now  
Old 03-31-21, 02:03 AM
  #14  
Fentuz
Senior Member
 
Join Date: Aug 2014
Posts: 150

Bikes: Dahon jetstream p8, customized helios & Plant X Free Ranger (modded of course)

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 46 Post(s)
Liked 29 Times in 27 Posts
It s not just the fork you need to upgrade, you need a strong headset too and the Brompton OEM bearing are unlikely strong enough to handle the added cantilever load.
to convert to front disc brake (especially hydraulic with 160mm disc), you would be a 16" fork with 100mm hub space that follow this design:
https://www.planetx.co.uk/i/q/FOOOCR...fork-disc-only
Or a Aluminium Hydro fork or carbon (not cheap or easy to hand craft)

and you would need to fit something like a BMX headset

Basically do what tern did with the Verge x11 or get Ben Cooper's kit: https://www.kinetics-online.co.uk/fo...n-disc-brakes/
Fentuz is offline  
Likes For Fentuz:
Old 03-31-21, 08:07 PM
  #15  
Nyah
Senior Member
 
Join Date: Sep 2018
Location: Shenandoah Valley, Northern Virginia.
Posts: 386

Bikes: '99 Trek 520, Konacado ('20 Kona Sutra) and a chromoly-framed folding bicycle with drop-bars and V-brakes, that rolls even while folded.

Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 208 Post(s)
Likes: 0
Liked 86 Times in 67 Posts
Without what is known as a thru-axle, a disc brake will not live up to its potential and, could be very disappointing. If the disc fork has a "C" shape in the part of the dropout where the axle goes, I recommend leaving it to rot on the retail floor. If investing in a custom-built disc fork, make sure that it's made with a thru-axle.
Nyah is offline  
Likes For Nyah:
Old 04-01-21, 04:31 AM
  #16  
Winfried
Senior Member
Thread Starter
 
Winfried's Avatar
 
Join Date: Aug 2011
Location: Paris, France
Posts: 2,101
Mentioned: 9 Post(s)
Tagged: 0 Thread(s)
Quoted: 386 Post(s)
Liked 58 Times in 49 Posts
My big bike with disk brakes has an open fork (not thru-axle)
Winfried is online now  
Old 04-01-21, 06:01 AM
  #17  
Jipe
Senior Member
 
Join Date: Feb 2017
Posts: 571
Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 261 Post(s)
Likes: 0
Liked 71 Times in 60 Posts
I agree, I have several disc brakes bikes, none has thru-axle but braking is excellent (including on a tandem bike on which the brakes must stop a much higher load than on a solo bike).

Remember that disc brakes were used well before thu-axle and performed very well.

What is well needed on the fork dropout is something that prevent the wheel to jump out of the dropouts.
Jipe is offline  
Old 04-01-21, 07:08 AM
  #18  
Winfried
Senior Member
Thread Starter
 
Winfried's Avatar
 
Join Date: Aug 2011
Location: Paris, France
Posts: 2,101
Mentioned: 9 Post(s)
Tagged: 0 Thread(s)
Quoted: 386 Post(s)
Liked 58 Times in 49 Posts
So, as an option, Brompton could offer a 74mm wide disk fork — with the disk on the right-side to avoid interfering with the fold à la Birdy — without making the bike much wider.

Winfried is online now  
Old 04-01-21, 10:18 AM
  #19  
Nyah
Senior Member
 
Join Date: Sep 2018
Location: Shenandoah Valley, Northern Virginia.
Posts: 386

Bikes: '99 Trek 520, Konacado ('20 Kona Sutra) and a chromoly-framed folding bicycle with drop-bars and V-brakes, that rolls even while folded.

Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 208 Post(s)
Likes: 0
Liked 86 Times in 67 Posts
Originally Posted by Jipe View Post
I agree, I have several disc brakes bikes, none has thru-axle but braking is excellent (including on a tandem bike on which the brakes must stop a much higher load than on a solo bike).

Remember that disc brakes were used well before thu-axle and performed very well.

What is well needed on the fork dropout is something that prevent the wheel to jump out of the dropouts.
That's what the thru-axle system is. You are refusing a good thing (thru-axle) just to refuse it.
Nyah is offline  
Old 04-01-21, 10:43 AM
  #20  
Jipe
Senior Member
 
Join Date: Feb 2017
Posts: 571
Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 261 Post(s)
Likes: 0
Liked 71 Times in 60 Posts
The Birdy has a 100mm OLD front.

But the disc mount is not only on the right side of the bike, the disc is also placed closer to the center of the wheel than on a standard front disc wheel (actually, the distance from the dropout to the disc of the Birdy front wheel is the same as the distance between dropout and disc on a standard rear wheel).

The thru-axle is just one solution, the others with pins or grooves.. also work.
Jipe is offline  
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
2jzsupragte
General Cycling Discussion
17
11-29-13 05:18 PM
JanekTheFizyk
Hybrid Bicycles
14
02-01-13 05:21 AM
CHAS
Road Cycling
4
10-01-10 10:20 AM
XCSKIBUM
Bicycle Mechanics
3
03-16-10 05:40 PM
xenologer
Bicycle Mechanics
7
12-25-09 12:53 PM

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off


Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service - Do Not Sell My Personal Information -

Copyright © 2021 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.