installing star nut

[jules21]

any tips on how to do this?

i tried wacking it, but it won't go in straight for some reason (possibly as i didn't cut the steerer perfectly flat).

youtube says to source a threaded rod and use that to pull the nut down, from underneath the steerer. that sounds good - any ideas where i would get a threaded rod? it would have to be really thin (can't engage the nut thread).

[twizzle]

Buy the tool.

Sent from my GT-I9100 using Tapatalk

[the grid]

Threaded rod usually at bunnings or fastener shops in a multitude of diameters and available in short lengths

[drubie]

There's a special tool

I use a small, buggered screwdriver whose shaft is smaller than the threaded hole in the middle. Go easy and they pop right in. In fact, I've never had a problem yet.

Getting 'em out however...

[Mulger bill]

Wanna expand on the screwdriver trick Drub'?, I'm not getting a mental image

I used an old bolt the one time I did a starnut. Eventually got some semblance of rightness, at the cost of a contused thumbnail.

Not worth removing them, just use some rod to bang 'em down outta the way.

[}SkOrPn--7]

i tried wacking it, but it won't go in straight for some reason (possibly as i didn't cut the steerer perfectly flat).

If you already have it in but not straight cut the end of a timber broom handle and place in the steerer tube and tap it gentle to level it up. Your best using a yard broom handle as the timber handle on them is a larger diameter than a standard broom. Or pop into Bunnings and go down to the timber section and you can purchase dowel in 600mm lengths for about 3 bucks to fit just nicely that all ready has a square end plus a snug fit.

Ricky

[drubie]

Wanna expand on the screwdriver trick Drub'?, I'm not getting a mental image

I used an old bolt the one time I did a starnut. Eventually got some semblance of rightness, at the cost of a contused thumbnail.

Not worth removing them, just use some rod to bang 'em down outta the way.

It's not much of a trick Mulger bill - I have a bad habit of bending/borking screwdrivers and just happened to bork a very small one with a decent handle (so, not one of the hard plastic handles but the yellow tough ones). The screwdriver is small enough that the shaft fits right down inside the threaded hole in a star nut but the handle sits on top offering something to push on / hammer on.

I would generally then use the screwdriver handle to push the first layer of star prongs into the fork. A few gentle taps with the hammer and it's sweet. Its pretty much like using a bolt but because the shaft of the screwdriver stops the handle moving about, you won't bash your thumb (I can't guarantee that). I must have done 4 this year and it never crossed my mind it was difficult.

but yeah, I found out the hard way that trying to get one out was an exercise in futility. Generally the steerers on forks are tapered narrower as they go down, so as you suggested just bash it down far enough to get it out of the way if you're re-using a fork for something else.

[Mulger bill]

Brilliant! Thanks Drub' Next time out, I sacrifice a screwdriver.

[jules21]

can't make it work. tried the screwdriver thing, but no matter what i do, one side of the nut slips inside the steerer before the other and then wants to go in sideways.

i've tapped one in before with no dramas, but this one seems to be giving me more trouble. maybe as the steerer is soft aluminium?

[Nobody]

Have you got the correct size star washer? From what I've seen on sale, steel and alloy ones can be different sizes although a recent search hasn't shown any. If the outers are the same size, say 1 1/8", then obviously the inner diameter is going to be smaller for Al than steel.

If it is really a problem, you could punch it all the way through and out, then start again with another washer. You won't be able to reuse the current one successfully which will be obvious once you inspect it after ejection.

[jules21]

it's definitely the right size - 25.4mm internal diameter steerer. the star nut is just bigger than it - it will go in, i just can't make it go in straight.

if i keep forcing it in, will it straighten up, or will it just go through sideways? i keep pulling it out before it gets too far in to remove.

[glennb]

it's definitely the right size - 25.4mm internal diameter steerer. the star nut is just bigger than it - it will go in, i just can't make it go in straight.

if i keep forcing it in, will it straighten up, or will it just go through sideways? i keep pulling it out before it gets too far in to remove.

Not necessarily, depends on your method.

I thread the star nut on to a 150mm bolt then hammer it in. The nut mostly self-aligns when the second star enters the steerer, but a few angled taps on the projecting bolt are usually required to get it prefect.

[drubie]

It's gotta be straight-ish when you insert the first set of stars but as glennb said the second set should pull it straighter. I didn't find any difference between aluminium and steel steerers though. Maybe you're being a bit timid?

One thing to watch is if it's a suspension fork, you have to support it under the crown rather than boing it all over the floor trying to get it it.

[jules21]

Maybe you're being a bit timid?

this turned out to be the problem! the first star went it at a wild angle, but the second star straightened it up when it contacted the top of the steer tube.


thanks for all the suggestions.

[Stuey]

Too late now, but also use a bit of grease/vaseline on the internal surface of the steerer...

[Nobody]

Too late now, but also use a bit of grease/vaseline on the internal surface of the steerer...

I've done this in the past to find the star washer would not grip. This was on a steel steerer though. Washers may have more bite into Al.

[Stuey]

Sorry, yes I did mean on aluminium, because the 'teeth' bite even on the way down.

[matth]

Again a bit late but I also use a piece of broom handle... I just cut about 50mm of the end of a yard broom handle as the rounded tip sits snuggly in the star nut... a small smear of grease (alloy steerer) and it taps in easily.

[Stuey]

Obvious I know, but I guess it should be mentioned (for the inexperienced) that you should support the fork under the steerer in between the fork tubes using something protective (I use soft wood covered in a cloth), and not under the dropouts...

[jules21]

Obvious I know, but I guess it should be mentioned (for the inexperienced) that you should support the fork under the steerer in between the fork tubes using something protective (I use soft wood covered in a cloth), and not under the dropouts...

i just used the plastic dummy axle that the forks came with. while this puts a load through the forks, i don't reckon it's that high.

[Nobody]

Obvious I know, but I guess it should be mentioned (for the inexperienced) that you should support the fork under the steerer in between the fork tubes using something protective (I use soft wood covered in a cloth), and not under the dropouts...

i just used the plastic dummy axle that the forks came with. while this puts a load through the forks, i don't reckon it's that high.

Tend to agree. If your fork can't take a few hammer blows while being supported by a dummy axle, then I wouldn't want to be riding on it.

[jules21]

Tend to agree. If your fork can't take a few hammer blows while being supported by a dummy axle, then I wouldn't want to be riding on it.

reminds me of when i was scrutineering at a Formula SAE event, where uni students build their own mini race cars. i helped lift one of the cars, as the students were struggling with it, grabbing it by the suspension control rod. one of the students demanded i let go, thinking it might not take the load. i should have given him a choice between failing his engineering course or the car

[Stuey]

Fair enough about the dummy axle if you have one, but I meant don't just stick the dropouts on the ground and whack it in. And if you're happy do do this, then fine - I wouldn't. Some star nuts take a hell of a whack to get in, depending on the thickness of the steerer tubing.

[twizzle]

Tend to agree. If your fork can't take a few hammer blows while being supported by a dummy axle, then I wouldn't want to be riding on it.

reminds me of when i was scrutineering at a Formula SAE event, where uni students build their own mini race cars. i helped lift one of the cars, as the students were struggling with it, grabbing it by the suspension control rod. one of the students demanded i let go, thinking it might not take the load. i should have given him a choice between failing his engineering course or the car

Were you creating a bending load in the control rod? Could have been interesting if they had only designed for tension/compression. Some people get carried away when it comes to unsprung weight.

Which is one of the reasons that carbon steerers scare the crap out of me - are they designed for 60kg riders or people like me who are north of 100Kg? Brakes on road bike sure aren't specced for people at my weight!

[jules21]

Were you creating a bending load in the control rod? Could have been interesting if they had only designed for tension/compression. Some people get carried away when it comes to unsprung weight.

it's funny as i was coincidentally talking with a mate on the weekend who built on those cars when he was at uni. he explained the same thing - that he had a teammate who was responsible for the suspension and who was desperate to work for an F1 team and thought winning this comp was his ticket to be recruited by ferrari. he designed the suspension using careful, theoretical analysis and came up with aluminium rods of 0.8mm wall thickness. looked good on paper, but failed the first time rubber hit the road. in real life, you can't design a member for pure tension or compression - buckling is an obvious factor. and if it's so weak it can't statically support 1/4 of a ~100 kg car, it's not raceworthy.