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 08-19-08, 08:47 PM   #1
mingonn
Senior Member
Thread Starter
 
Join Date: Dec 2006
Bikes:
Posts: 52
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Fitting BMX forks to a dahon?

Hi all,

I am trying to electrify my Danon, convert it to electric that is. I have a front hub motor that is for a standard 100 mm hub width and I need to change my narrow forks to ones that fit.

BMX forks come to mind but they are all un threaded ahead styled steer tubes, unfortunately I have an older model dahon with a quil setup and threaded forks.

I am pretty sure I can get the standard BMX 1 1/8 steer tube threaded but will my quill still fit? I noticed there is some pretty sever butting in my current steer tube and I am not sure if they bother with ahead setup.

Has anyone out there tried fitting 100m forks to their dahon?

Cheers
Derek

Last edited by mingonn; 08-19-08 at 08:50 PM.
mingonn is offline   Reply With Quote
Old 08-20-08, 03:45 AM   #2
jur
Senior Member
 
Join Date: May 2005
Bikes:
Posts: 6,806
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 8 Post(s)
You will have to measure some dimensions for anyone to be able to answer.
jur is offline   Reply With Quote
Old 08-20-08, 10:10 AM   #3
chagzuki
Senior Member
 
Join Date: Jul 2008
Bikes: Brompton, Dahon Vitesse D5
Posts: 1,867
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Dahon headsets are partially built into the fork, I've just discovered. I can't see any easy way to adapt a standard fork so that it fits, unless there's a headset upgrade where the lower portion isn't integrated into the fork?
chagzuki is offline   Reply With Quote
Old 08-20-08, 12:21 PM   #4
tinmantis
tinmantis
 
Join Date: Aug 2008
Bikes:
Posts: 8
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
I don't know much about Dahon's but...
are you sure you'll need a 1+1/8th steerer? my 3 vintage folders are all 1"

Some BMX forks DO come threaded (I just got one) but road stems/road quills do not fit down them. One inch road stems are 22.2mm outside diameter, and BMX !" steerers are 21.1mm inside diameter.
but
I had a machine shop ream my BMX steerer up to 22.2mm ID, so I can use road 'stuff' with it...
but watch your headtube height. BMX forks come with different size steerers, short and long
hope that vaguely helps!
regards
jon
tinmantis is offline   Reply With Quote
Old 08-20-08, 01:15 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)
Just get a cheap boys MTB
rip the forks from it

But check the handlebar stem is the right diameter.
Just need to remove the stem and see the number on it
griftereck is offline   Reply With Quote
Old 08-20-08, 08:43 PM   #6
mingonn
Senior Member
Thread Starter
 
Join Date: Dec 2006
Bikes:
Posts: 52
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
I have take some photos showing the current setup. Quill has 25.4mm stamped on it and forks have 20x116 stamped.

I think there is a bicycle recycle place near me so I might just take the forks and quill down and try my luck.

The cheap boys 20" mtb sounds promising.

Cheers
Derek
Attached Images
File Type: jpg photo 001 (Small).jpg (32.2 KB, 17 views)
File Type: jpg photo 003 (Small).jpg (44.3 KB, 10 views)
File Type: jpg photo 004 (Small).jpg (25.2 KB, 11 views)
File Type: jpg photo 008 (Small).jpg (25.5 KB, 10 views)
mingonn is offline   Reply With Quote
Old 08-21-08, 01:28 AM   #7
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 I didnt know the size
Cheap MTBs will be 22.2mm handlebar stem size.

So you'd have to look hard to get a threaded fork in 1 1/8" oversize
As thats the common Aheadset size.

Looks like the bearing race on the forks is a normal removable one.
griftereck is offline   Reply With Quote
Old 08-21-08, 02:19 AM   #8
mingonn
Senior Member
Thread Starter
 
Join Date: Dec 2006
Bikes:
Posts: 52
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
This is getting harder and harder.

Went down to the second hand bike shop and it seems that 1 1/8 steer tubes designed for ahead stems are not internally butted so will not accept my dahon quill. Now I am stuck with converting the whole lot over to ahead.

Fall back plan now is to see if I can get 1 1/8 threaded rigid mtb forks and shorten them. Failing this I will try using a pair or un threaded BMX forks and extend the 1 1/8 steer tube to the height of my handle bars. Will need to work out a way to still allow me to pull the steer tube extension off whilst keeping the head set tensioned.

Derek
mingonn is offline   Reply With Quote
Old 08-21-08, 08:05 AM   #9
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)
you could use a 28.6mm seat clamp on the steerer tube, to keep the headset on.
griftereck 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 05:13 AM.