Cycling and bicycle discussion forums. 
   Click here to join our community Log in to access your Control Panel  


Go Back   > >

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.

User Tag List

Reply
 
Thread Tools Search this Thread
Old 06-16-09, 07:01 PM   #1
stevegor
Senior Member
Thread Starter
 
stevegor's Avatar
 
Join Date: Dec 2006
Location: Oz
Bikes: lots... even a Raleigh twenty !!!
Posts: 2,117
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Another R20 mod question

I'm using a BMX fork with Vbrake bosses for my next project, problem is the steerer is just too short for the R20's head tube, so do I...

1: Cut the head tube down to fit, which means I need a longer headstem, (no problem there), or....

2: Put a 22.2mm insert into the BMX steerer, then add approx 2.5 inch length of threaded steerer over the insert then drill holes and spot/tack weld it all together. This is quite a safe process and it would keep the R20's front angle original.

Opinions please,
stevegor is offline   Reply With Quote
Old 06-17-09, 04:46 AM   #2
ogeluv
Junior Member
 
Join Date: Sep 2008
Location: detroit area
Bikes: mongoose pro dx mtb, r20
Posts: 21
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
I had such a tough time with the fork on my r20. i thought about cutting the head tube as well, but i saw a few pics of that mod and imho it destroys the look of the bike. if you can stretch the bmx steerer and its good and straight (welding has a tendency of moving things around even on the best of set ups)i would go that route. on my 20 i wanted to use the qr and have the max height adjustment so i pressed the steerer from an rst sprite out and had the longest threadless steerer available threaded on a lathe. (a few pics are in another post). this gave me around 6+ inches of adjustment in height. on my next 20 i plan to try a disc version so ill probably modify a bmx fork the same way and then some. ill use a soma hi rider quill stem so my height will be fixed but i found it not to be as big a deal as originally thought. by no means will i even consider cutting the head tube. its like cutting the tailfins off a classic car.
ogeluv is offline   Reply With Quote
Old 06-17-09, 04:58 AM   #3
griftereck
Senior Member
 
Join Date: Jun 2008
Location: angus scotland
Bikes: Grifter BSA 20
Posts: 600
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
are you sure 22.2mm fits in there. BMX quill stems are usually 21.1mm.
You can get some MTB stems in 21.1mm but I havent seen any road stems that size. BMX stems are short reach, so the bars are a bit close.
I geuss you could ream it out. You can get adjustable reamers that size

I would cut the Headstock. Maybe below the cross bar. This would give a more sporty head angle. But might lead to pedal strike, on the ground.

I have heard of a tube lengthening process. Where the 2 tubes are put together and clamped down onto a bit of angle iron. this holds them straight. Not tried it though.
griftereck is offline   Reply With Quote
Old 06-17-09, 06:37 AM   #4
stevegor
Senior Member
Thread Starter
 
stevegor's Avatar
 
Join Date: Dec 2006
Location: Oz
Bikes: lots... even a Raleigh twenty !!!
Posts: 2,117
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
The BMX fork's steerer is definitely 1" and I've tried a 22.2 road quill stem which fits OK.

No problem with pedal strike as I'll be using 145mm cranks.

I would like to keep the head tube original if possible, so lengthening the steerer might be the way to go. However, with the BMX fork I can't "sweat out" its steerer then add a longer one, it's too big a job and I'd probably botch it, so I might use the angle iron idea and see what happens.

Last edited by stevegor; 06-17-09 at 06:37 AM. Reason: add
stevegor is offline   Reply With Quote
Old 06-17-09, 12:08 PM   #5
griftereck
Senior Member
 
Join Date: Jun 2008
Location: angus scotland
Bikes: Grifter BSA 20
Posts: 600
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Oh yeah I meant that the 2 tubes are clamped down into the angle iron. Then the tubes are welded together. The angle iron holds it straight.
Think it was on Atomic Zombie that I heard about it.
Maybe cover the threads on the steerer tube with oil to stop it getting damaged by weld splatter.
Might be a plan to use an inner sleeve. Cut the top part of a steerer tube so you can get your stem into it a good amount. Then cut your forks steerer tube to length to make it the proper total length. Got to watch that the steerer tube get a thinner internal diameter near the bottom
griftereck is offline   Reply With Quote
Old 06-17-09, 05:34 PM   #6
stevegor
Senior Member
Thread Starter
 
stevegor's Avatar
 
Join Date: Dec 2006
Location: Oz
Bikes: lots... even a Raleigh twenty !!!
Posts: 2,117
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by ogeluv View Post
I had such a tough time with the fork on my r20. i thought about cutting the head tube as well, but i saw a few pics of that mod and imho it destroys the look of the bike. if you can stretch the bmx steerer and its good and straight (welding has a tendency of moving things around even on the best of set ups)i would go that route. on my 20 i wanted to use the qr and have the max height adjustment so i pressed the steerer from an rst sprite out and had the longest threadless steerer available threaded on a lathe. (a few pics are in another post). this gave me around 6+ inches of adjustment in height. on my next 20 i plan to try a disc version so ill probably modify a bmx fork the same way and then some. ill use a soma hi rider quill stem so my height will be fixed but i found it not to be as big a deal as originally thought. by no means will i even consider cutting the head tube.
its like cutting the tailfins off a classic car.
Or de-seaming a mini Cooper S?
stevegor is offline   Reply With Quote
Old 06-17-09, 05:36 PM   #7
kraftwerk
my nice bike is at home
 
kraftwerk's Avatar
 
Join Date: Feb 2006
Location: Brooklyn, NY
Bikes: 2011 BMC Race Machine / Colnago ct 1 / 80's Rossin / 90's Merlin/ 70's Raleigh 20/ Swift folder, etc.
Posts: 720
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Don't cut the frame!
But let us know what product combination or custom fittings you decide on...
kraftwerk is offline   Reply With Quote
Old 06-17-09, 05:37 PM   #8
kraftwerk
my nice bike is at home
 
kraftwerk's Avatar
 
Join Date: Feb 2006
Location: Brooklyn, NY
Bikes: 2011 BMC Race Machine / Colnago ct 1 / 80's Rossin / 90's Merlin/ 70's Raleigh 20/ Swift folder, etc.
Posts: 720
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Some people cut the rain gutters off 70's and 80's Porsche's and I always think that it is such a shame!
kraftwerk is offline   Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search

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



All times are GMT -6. The time now is 07:49 PM.