1 1/8" forks on 1" frame???? :S

i recently made an ebmx of sorts.... out of a girls 20" full suspension moutain bike.

the front forks are a little weedy so i got myself a better set of 20" front suspension forks.

problem is im going from a 1" threaded steering tube to a 1 1/8" threadless steerer tube.

i have options but most of them seem bodge or a lot of effort.... 1-3

1. weld exsisting bearing cups to the frame, then dremmel out their internals untill the steering tube fits.

2. cut out the exsisting headtube from the frame and weld in a larger headtube.

3. weld larger sections of headtube to exsisting headtube on either end...

4. find bearing cups that mount to my exsisting headtube externally instead of internally. (except i cant find them, do they exsist?)

id like to do option 4.......but i cant find anything even close to this.

little help/advice would be appreciated?

5. find a bike with 1-1/8"

jimmyhackers said:

4. find bearing cups that mount to my exsisting headtube externally instead of internally. (except i cant find them, do they exsist?)

id like to do option 4.......but i cant find anything even close to this.

little help/advice would be appreciated?

Click to expand...

I've used these cups from slidestar several times and they work great.

https://slidestar.com.au/wp/shop/fork-conversion-cup-kit-for-huffy-slider/

By the time you get finished bodging something together that makes another problem for you later, you'll have spent more time, effort, and resources on doing the job poorly than you would have acquiring a more suitable frame.

I once retrofitted a 1" frame MTB with a super heavy duty 1" fork, for a very fat but physically active kid. I used .250" wall seamless chromoly tube which I transplanted into a 1-1/8" chromoly fork, and used a 1" threadless headset.

No bodge required, adapter just works

briangv99 said:

No bodge required, adapter just works

Click to expand...

That seems okay if you make the cups to fit the OD of the specific head tube, and if your head tube is relatively short and the steer tube made from steel. The clearance between a 28.6mm steer tube and a 1" head tube that is reamed to 30.0mm or 30.2mm on the ends can be less than 0.5mm. Under the rider's weight, the steer tube can easily flex enough to rub the inside of the head tube and bind the steering. When braking or encountering bumps, there certainly will be contact between the steerer and the head tube bore.

I just welded a new headtube on the front of the other one. Still worked after a few years of heavy-duty usage. (I had all sorts of problems with mismatched bearing/cup/etc sizes...but nary a problem with the headtube itself)

Before finishing-up but after welding on side-bars:

right after welding tube on, before side-bars:


Something like 5+ years later (almost 5 years ago, now)

I'm sure it'd still be working if I was still using that bike.

thanks for the replies.

the adpator looks good, apart from the price.

however, i bought the right sized tube and have cut/welded it to my bike frame.
was less than £20 for the pipe, only took an hour and some constructive swearing.

alls well.
thanks again