Mechanics and Fixing Any Questions Answered

Use the right barb for the hose.

I think I wasn't very clear...
I want to use the Deore calipers = BH90
And the MT447 brake levers = BH59.
Let's say I use a BH59 hose, then I need to use a BH90 barb to make it work with the caliper, right?

If you choose to replace the barb and olive then you'll need BH59 ones (technically only the barb differs, olives are the same), or you can reuse the current barb and olives.

The barb has to match the hose.

Okay so BH59 hose on BH90 caliper will work fine? And visa versa?

Yeah, I have BH59 hose on XT m8000 lever and caliper which also takes BH90 and it's fine.

Match the right barb to the hose and you'll be fine.

Thank you! I read somewhere that the barb needs to match the caliper that why I got confused.

The replacement bearings, have discovered when getting is2 replacements that there can be a discrepancy of a couple of mm in the thickness of the bearings, because there are no standard sizes cos cycling makers love not sticking to standards.

I’ve been installing one of these InniCycle headsets which convert 1” threaded to a 1-1/8” threadless steerer on a mid 90s Italian steel frame. The crown race is 26.4 standard, the issue is that when I went to fit this on the fork it just dropped on as it’s slightly too big. At first I thought maybe it’s some weird Italian sizing on the fork but from what I can see on Sheldon’s that would make it slightly larger than 26.4. Perhaps at some point someone has been a bit over zealous with the file is the only explanation I can think of.

Anyway I slapped some grease on the crown race and fitted the fork into the head tube and screwed on the top section just to see how it all came together. I’ve not tightened the expanding bolt yet but the fork and headset rotate smoothly with no play already.

My question is given the top section of this headset screws onto the threaded steerer do I need to worry about the loose fit on the crown race or should I start cutting up coke cans and shim it on to get a tight fit?

https://youtu.be/jhD8evK6jLg?si=2APjzLFlhfx-sszV

do I need to worry about the loose fit on the crown race

Yes. On a conventional headset, not having the crown race be the correct press fit on the steerer will permit radial play, which will show up as clunks in the steering and braking and accelerated wear on both headset bearings.

The innicycle site is down for me so I can't tell what kind of bearings it uses, but if they're common angular contact cartridge bearings with chamfered seats, there are two possibilities:

1. the "crown race"(actually the seat for the cartridge bearing inner race housing) is already split, and it's going to do what it should or
   
2. the "crown race" isn't split, and you can split it to make it do what a collet should, and what a collet does for all AHeadSet upper bearings and quite a few lower ones
   

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Back in the 70’s we would use a centre punch around the top of the fork where the race fits to raise islands of metal and then knock the race in place. Maybe this post should be in the bodging thread ?

The shop I worked in Oz had a J.A.Stein knurling tool to enlarge the crown race seat. That was in the days of loose bearing headsets and a split crown race was generally considered a bad thing.

https://steintool.com/portfolio-items/knurling-tool/

I am not sure how a split crown race helps the situation unless it is on a tapered seat or the tapered bearing doesn’t bottom out on the split crown race.

The crown race is not split, looks like the pic below and it does use standard cartridge bearings with a chamfered side.
I don’t think splitting the race would solve the issue.
I think I’d rather try shimming it than punching the metal of the fork crown.

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• IMG_7077.webp

I don’t think splitting the race would solve the issue

Google "split crown race". Loads of cartridge bearing headsets come with split crown races, the chamfer transfers axial load into radial compression of the "race" (collet) so the higher the axial load, the tighter the collet grips the steerer. This is also how the preload adjuster at the top solves the issue of the upper bearing collet not being a press fit on the steerer.

The simple machine which does this is called a wedge (in this case wrapped into a cone)

Of course, you could be right, if the difference between the diameters is so great that the bearing bottoms out on the flat face of the seat before the collet has shrunk enough to grip the steerer. You'll be able to predict this by taking appropriate measurements (will probably require a feeler gauge to check the clearance between the bearing and the flat face of the seat) and using trigonometry.

You'll be able to predict this by taking appropriate measurements (will probably require a feeler gauge to check the clearance between the bearing and the flat face of the seat) and using trigonometry.

Or you could just hold the bearing on the crown 'race' and hold it up to the light to see if you have any gap to play with.

If cutting a slot in the 'race' won't work due to no or insufficient gap to make it work as a collet, maybe try this before you take the scissors to the beer can:

BITD when I used to volunteer at a community bike workshop, we'd get this all the time. I developed what seems like a terrible kludge which actually turned out to be quite robust - just use sellotape. Take note of where you start so you can stop just short of the spot to keep it round, and pull it tight to reduce its compressibility. Apply more than you'll need and remove layers as necessary until you can just squeeze it on without tearing up the tape. It'll be pretty solid when it goes on, and should actually last pretty well, surprisingly enough. I think maybe the combination of pressure and time makes it go a bit hard?

Obviously, if you need to build up more than half a mm or so, the tape will want to start creeping around... You could try other tapes, but you've gotta find one with a good trade-off of resistance to compression against resistance to tearing as you fit the crown race. Aluminium tape is the only other tape I've tried which can work, but the ones I've come across are tediously thin.

I think maybe the combination of pressure and time makes it go a bit hard?

What temperature is this structural tape?

TBF, I think I've done a combination of most of these to get some shitters running for a bit longer.