Steel fork stretch?

[Architectonic]

Is it realistic to stretch an 85mm fork to fit a 100mm front motor without much problems? (currently measure around 90mm, hmm...)

Assuming a single Grin-Tech torque arm, steel fork (for 20" rim) and a max of about 500w?

 

[d8veh]

I've stretched two 20" and one 26". They go pretty easily. I put two planks between them and pull them apart. If one side goes too far, I tap it back with a mallet. You'd be surprised at how easy it is.

The only thing you have to look out for is whether you have enough width further up from the drop-outs. Sometimes the fork leg can catch the corner of the motor.

 

[docnjoj]

I've stretched two 20" and one 26". They go pretty easily. I put two planks between them and pull them apart. If one side goes too far, I tap it back with a mallet. You'd be surprised at how easy it is.

The only thing you have to look out for is whether you have enough width further up from the drop-outs. Sometimes the fork leg can catch the corner of the motor.

I had this situation with our old Bike-e. Steel fork. Bikeshop helped with their giant vise and great skill. Four mild bends to clear an old Crystalite brushed motor. Sand and repaint after. This was 10 years ago and the bike still runs fine. Bike shop really knows what they are doing. Don't try this with alloy fork.
otherDoc

 

[Ykick]

I've stretched two 20" and one 26". They go pretty easily. I put two planks between them and pull them apart. If one side goes too far, I tap it back with a mallet. You'd be surprised at how easy it is.

The only thing you have to look out for is whether you have enough width further up from the drop-outs. Sometimes the fork leg can catch the corner of the motor.

Exactly what I've run into doing this....

 

[bowlofsalad]

One potential technique for this that I've read about involves a small jack. I think the benefit to this is ease and even distribution.

 

[Lebowski]

i think it depends on how good your dental insurance is...

 

[peters]

If the dropouts are strong enough, I would do this with a threaded rod and 2 washers+nuts on the internal side, and twist.

 

[John in CR]

i think it depends on how good your dental insurance is...

My thoughts exactly, though I'd have to evaluate it on a fork-by-fork basis.

 

[drsolly]

I just did this using a screw jack.