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
   

1 Attachment

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.

1 Attachment

• 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.

The good stuff can withstand more than three hundred Kelvin

I have a split crown race on my carbon bike but that has a tapered steerer so wasn't sure the same principle would apply in this instance. I've just taken the fork out and the measured the crown width with some digital calibers and its coming in around 26.2mm so I'm short by .2mm.

Took a couple of pics of the fork crown with and without the 'race' on it. Also sat the bearing on the crown race and there is a small gap between them.

Seeing as this is a £100 headset I'm not that keen on cutting it up which is why I'm leaning more towards trying the coke shim or even giving this "Sellotape" method a try!

3 Attachments

Seeing as this is a £100 headset I'm not that keen on cutting it up

Invest £5* in a split crown race with the correct chamfer (36° or 45°, if it's not marked on the bearing ask innicycle to confirm)

Or invest in a new fork, which should have the correct diameter to press on the bearing seat and also won't come with that nasty pitting which is where the crack that eventually snaps the fork will start.

*£4 if you just want a solid 26.4mm×45° one from my parts bin which you'll have to split yourself, $35 shipped for a spare from Innicycle

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

For some reason I was initially thinking about it upside-down, as if this old fork had an integral tapered seat like a modern carbon one. Of course there's no need for a gap under the 'race' - if the proposed slot does any work, it'll be closing up as the bearing moves down on it. Now that I look again, it's clear you're saying you'd need a gap between the bottom of the bearing and the 'race' - I'm getting sick of the scare quotes, is there another name for it? Rather not confuse it with an actual crown race

Might be a bit too generic here but I am trying to work out next steps with something.

My son has an old GT with a 1" threaded headset on the original fork, quill stem. The fork has that channel cut into the threads for the old style lock ring headset washers.

I installed a new headset myself (Tange something) when I built up the bike, but now I can no longer tighten it without the top bearing race just sort of slipping / letting loose. It does this before I can tighten it enough to remove all the play. The top lock nut sort of helps, but there still is slop in the headset.

My current theories and solutions are:

1. Headset top bearing race threads are fucked -> replace headset
   
2. Fork threads are fucked -> replace fork
   
3. Not enough fork threads for the top bearing race -> get more threads cut in fork OR replace fork
   
   

I have a new headset and can source a new fork, but I would prefer to keep the original fork if possible. But it may not be.

Which of those three is it most likely? I just want to know where to point the money gun. Ta.

It's quite easy to check these 3 points right?

Sometimes if the thread slot is munted and/or the tab on the washer is mashed, it's better to just file off the tab so it stops interfering with the situation.

But yeah, I've also come across some quite severe rattles between steerer and cup; with the headset as well-adjusted and tightened as possible, a clunk under hard braking followed by the headset inevitably loosening itself ensues. Kind of amazed in retrospect it never occurred to me to try thread tape in such instances... I guess I only started using it after I no longer had much to do with threaded steerers.

If the threads don't go down far enough on the steerer, that should be obvious as hell - spin the cup all the way down and it stops rattling on the steerer but the fork still rattles in the headset.

Keep your money gun holstered IMO - unless you don't have any thread tape. If you can get enough jammed in there, it should compress pretty hard and allow the locknut to hold the cup solid. It might take a couple of goes.

Right GRX 820 12 speed shifter is slow / sticky to return to centre after shifting up (whole lever swing left). I came down on that lever a while ago and filled it with mud but it seemed to get back to normal on its own, now it’s bad again.

I’ve tried to get all the dry mud out and sprayed in some silicone lube but it’s not helped much. Still need to return it manually.

What’s next? Tear down?