I consider myself pretty handy when it comes to building bikes and am pretty comfortable taking most bikes apart and re-building them. That is until I came across the lefty fork. Sweet Lord, I don’t know who designed that thing but what a PITA.
The instruction manual for assembly/ dis-assembly shows a hammer!!! And you need it!!! Once you take that fork off your bike, trying to get it back around the headset without mangling the washer that protects the bearings is a near impossibility. It is like everything was designed slightly too large/ tight, but is meant to fit flush. So you solve this with a hammer…
If anyone on here knows the trick for getting it back on I would love to know it. For me it involved a few hours, much hammering and 3 washers (2 mangled beyond use). I am never taking this thing apart again.
I was going to change my fork myself but when I downloaded the instructions from Cannondale I noticed they suggested using a special tool (Ernie?) to prevent the problems you mentioned. So I took it to the bike shop.
Ice! Oh that is smart, solve the problem with Physics. Have you done this, or is this a trick you have used in similar situations that you think might work?
I’ve done it with a Cannondale crank. Works like a charm. The fit is very tight and if you pound it in without the freezer I always worried about damaging the bearings. Their isn’t a way for the force to not travel through the bearings during the operation.
With the freezer is slides right in with pretty minimal tapping.
The Ernie is only needed to get the the steerer tube in and out. My issue is re-assembling the thing and lining it up, before the steerer tube goes back in. Ernie doesn’t help here, as far as I can tell.
This all began b/c I was annoyed at having to buy special (overpriced) stems, b/c the XC3 steerer tube is a different diameter to most other bikes. Then I found an alternative steerer tube that allows you to use regular stems. Getting the old steerer tube off was a bit of a fight (Ernie would help here, I improvised with some PVC piping), but once it is out the fork slides off. So far so good. But then, when you re-assemble and try to “slide” the fork back on (before inserting the steerer tube) you find you are in for a fight.
This process is only necessary because the lefty has no way to load the headset bearings (so no star nut or anything). Instead they just make everything in the headset area really tight and then wedge the headset between the upper and lower collars on the lefty fork. Frankly the design is crappy.
I was watching “How it’s made” with my daughter and the cylinder head or cylinder cap for a ferrari engine is soaked in liquid nitrogen, the assembler literally drops it into place and makes sure it is sitting flush, then as it expands it seals into place, no pressing involved.
i’ve removed my lefty to swap the upper and lower bearing cups on my scalpel (make it more slack) without any problems. the ernie tool helps a ton, and one needs to be careful when sliding everything back together. no liquid nitrogen involved.
I was pretty much assuming that the OP had ice water but not liquid nitrogen.
Liquid nitrogen and ‘tapping’ with a hammer may not be the best mix. The whole fork could end up in a million pieces on the floor, not just the needle bearings!
