How hard for someone with no framebuilding experience to construct a Brompton fork?
02-11-12, 08:55 AM
#1
Senior Member
Thread Starter
Join Date: Jul 2008
Posts: 1,984
Bikes: Brompton, Dahon Vitesse D5
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 55 Post(s)
Likes: 0
Liked 1 Time
in
1 Post
How hard for someone with no framebuilding experience to construct a Brompton fork?
I like folding bikes, however there are aspects of their design that persistently frustrate me. I find myself wanting to redesign them myself.
I've never brazed anything, never sourced lugs, crowns etc.. How tricky would it be and what cost would be involved would in attempting to replicate something like this?:
The geometry is unique: how would I obtain fork blades of the correct length? Would it be easy to find a crown of that flat shape so that the threaded section could be brazed on top (with 1 1/8 steerer)? What problems will likely arise?
The primary reason for doing this would be to have a threadless steerer tube, and then to redesign part of the stem, it's an idea that's been floating round my head for a while now and I figure I ought to get a better idea of the feasibility.
I've never brazed anything, never sourced lugs, crowns etc.. How tricky would it be and what cost would be involved would in attempting to replicate something like this?:
The geometry is unique: how would I obtain fork blades of the correct length? Would it be easy to find a crown of that flat shape so that the threaded section could be brazed on top (with 1 1/8 steerer)? What problems will likely arise?
The primary reason for doing this would be to have a threadless steerer tube, and then to redesign part of the stem, it's an idea that's been floating round my head for a while now and I figure I ought to get a better idea of the feasibility.
02-11-12, 09:24 AM
#2
Senior Member
Join Date: Sep 2008
Location: Collegeville, PA
Posts: 1,350
Bikes: Ruckelshaus Randonneur, Specialized Allez (early 90's, steel), Ruckelshaus Path Bomber currently being built
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 4 Post(s)
Likes: 0
Liked 1 Time
in
1 Post
Wouldn't be difficult for someone who's done it before, but not a job for an absolute novice.
However, if all you want to do is replace the steerer, that's more do-able, as the steerer tube is about the easiest piece to braze. Getting it hot enough to remove is another story. And, of course, you'd need to strip the paint off the fork first.
However, if all you want to do is replace the steerer, that's more do-able, as the steerer tube is about the easiest piece to braze. Getting it hot enough to remove is another story. And, of course, you'd need to strip the paint off the fork first.
02-11-12, 10:51 AM
#3
Senior Member
Join Date: Dec 2010
Location: B.C.
Posts: 189
Bikes: ritcheys{2** rm blizzard Geo elrick drop frame and acollection of parts bikes in waiting
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 2 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
A suggestion , take a look at a" Dursley Pedrerson" design using small dia. tubes , A head set . ,alloy disc brake
02-11-12, 10:56 AM
#4
Senior Member
Join Date: Dec 2010
Location: B.C.
Posts: 189
Bikes: ritcheys{2** rm blizzard Geo elrick drop frame and acollection of parts bikes in waiting
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 2 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
Steering tubes, off of a suspension fork ,Bottom and top fixing by current star washer systems, Make your own do a "Instructables"
02-11-12, 12:00 PM
#5
Senior Member
Thread Starter
Join Date: Jul 2008
Posts: 1,984
Bikes: Brompton, Dahon Vitesse D5
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 55 Post(s)
Likes: 0
Liked 1 Time
in
1 Post
Wouldn't be difficult for someone who's done it before, but not a job for an absolute novice.
However, if all you want to do is replace the steerer, that's more do-able, as the steerer tube is about the easiest piece to braze. Getting it hot enough to remove is another story. And, of course, you'd need to strip the paint off the fork first.
However, if all you want to do is replace the steerer, that's more do-able, as the steerer tube is about the easiest piece to braze. Getting it hot enough to remove is another story. And, of course, you'd need to strip the paint off the fork first.
Last edited by chagzuki; 02-11-12 at 05:18 PM.
02-11-12, 03:48 PM
#6
Randomhead
Join Date: Aug 2008
Location: Happy Valley, Pennsylvania
Posts: 24,392
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 4 Post(s)
Liked 3,693 Times
in
2,515 Posts
most framebuilders will not touch a steerer replacement. There are a few that will splice a new steerer onto the old one. Rody at Groovy has a video somewhere of how he does it, a quick search failed to find it
02-11-12, 05:19 PM
#7
Senior Member
Thread Starter
Join Date: Jul 2008
Posts: 1,984
Bikes: Brompton, Dahon Vitesse D5
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 55 Post(s)
Likes: 0
Liked 1 Time
in
1 Post
If I were to make it from scratch what'd be the best solution for the fork blades? I don't know how it's normally done. . . I'm imagining that in this case I'd source some standard size blades and cut them down. But perhaps this wouldn't make for a clean fit in the crown? The other consideration is that the front hub is 74mm OLD.
02-13-12, 12:09 PM
#8
Senior Member
Join Date: Feb 2010
Posts: 114
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
I've got a pair of True Temper recumbent fork blades that I'm not particularly attached to, but depending on the length needed I'd probably just look into cutting down regular blades as necessary. Ride is clearly not something that is a big concern judging from the fork in the photo.
I've also cut down a bonded alumnium straight leg mtb fork in the past, if the rake is what you want it isn't that huge a deal, but that doesnt the 74 old issue.
I've also cut down a bonded alumnium straight leg mtb fork in the past, if the rake is what you want it isn't that huge a deal, but that doesnt the 74 old issue.
