bearpinata

Hi folks,

My gf stored her bike on her balcony and the front suspension fork filled up with water and seized completely. It's been soaking in WD-40 for weeks, I've tried everything to loosen it up but it's just a solid block of rust inside and won't budge. Right now it's basically a very heavy rigid fork.
The bike is a Mongoose Crossway and for some strange reason even though these are 2013 bikes with a 50mm head tube diameter they went with a 1" threaded fork and quill stem
Is it possible to convert it to a threadless fork?

I realize that on road bikes built for 1" threaded stems swapping to threadless can be impossible or tricky because the head tube is too narrow, but here I have 50mm of diameter to work with.
Can't I just remove the front fork, press out the old headset bearings, buy a new set of bearings for threadless, and swap in a new threadless fork?

Is this possible? If so, how do I find out the type and diameter of races/bearings I need? There's nothing written on the existing ones and I can't find any info from Mongoose. I figure I can measure them with a caliper once I press them out but ideally I'd like to have all the parts necessary for a swap pre-ordered so her bike isn't sitting taken apart for weeks.

Any help would be greatly appreciated.

ljsense

Yes, it is possible and I believe much less complicated than you fear.

Some track and BMX bikes have slightly different internal diamaters and take special headsets, but for the most part, a 1" head tube will take a 1" headset and a 1" threadless fork.

The hard part for most home mechanics is pressing in the headset, but if you've got that covered, you're basically home free.

One thing I want to make clear, though, is that you're not just replacing the headset bearings -- you're replacing the the headset cups themselves, which press into the frame. If I've lost you here, I think you probably want to head to a shop.

But if you're on top of that, and just referred to the cups as bearings, what you'd need to get are:

1. Any normal 1" threadless headset with a star-fangled nut to insert into the fork and a compression top cap.
2. A 1" threadless fork
3. Something to knock out the old headset cups (there are tools just for this, but a length of copper pipe and a hammer work)
4. A headset press, which is an expensive tool. Somewhat sketchy DIYers will show you videos of how to use a threaded rod, nuts and big washers or blocks of hardwood.

terrymorse 

If you can find a headset that fits your head tube, it should be no problem.

You will need to remove the headset to find out the fit diameter of your head tube. Then go looking for a headset.

bearpinata

Thanks.
I know about the cups - I incorrectly referred to them as bearing races, I'm not really at home with bike terminology

Why would I be limited to a 1" fork?
The head tube is around 50mm in diameter. I tried to post a pic but since I'm a noob I can't post images or urls yet.

A quick search shows that there are complete headset bearing sets for 47, 49, 49.5, 49.7, 50, 52mm head tubes, made for 1 1/8" forks.
Isn't it just a matter of finding the exact head tube size, pressing out the old cups from the head tube, pressing in the new kit, and I can use any 1 1/8" threadless fork?

bearpinata

Thanks.
So I'll actually need to hammer out the old 'cups' and get the inside of the headtube (top and bottom - although I doubt it's tapered) measured with a caliper? I notice there's 49, 49.5, 49.7, 50, etc mm bearing kits.. that doesn't leave a lot of room for error.
I was hoping they'd be "standard" sizes like 44mm, 48mm, 52mm, etc - those I'd be confident calipering. I'm not sure I can precisely measure the difference between 49.5 and 49.7mm

ljsense

You might have a frame I have no experience with; sorry to be giving you sort of blind advice. Every frame I know that came with a 1" threaded headset and 1" threaded fork won't fit a 1 1/8" fork. The head tube is just too narrow for the steerer to fit. The inner bore of a headtube that takes a 1" fork is pretty standardized, with BMX and track exceptions, but maybe yours is another exception?

Are you sure the fork you're pulling out has a 1" steerer?

bearpinata

Yeah it's an aluminum frame Mongoose Crossway MTB.
The head tube is around 50mm. There's a lot of room in there.
I can't post images here yet, but maybe you can see this?
imgur.com/naBuBoT

(I hope I'm not violating some rule by posting a link).

ljsense

That looks to me like it has a 1 1/8" steerer; maybe someone else can chime in with 100 percent certainty. One-inch threaded stuff is more vintage, like early 90s and before, usually.

bearpinata

1", for sure. Just doublechecked with a caliper.
The whole design just baffles me. The bike is from 2013-2014 and they used a 1" threaded fork on a 50mm diameter MTB head tube? It makes no sense.

ljsense

Huh. Yeah, that's new to me. I don't know what fork you have your eye on, but I wonder if you could find a used replacement for less money and hassle and come out ahead. Or just accept that it's a really heavy rigid fork now instead of one that had basically no useful suspension to begin with.

But you asked about fixing it, so I guess your best bet would be to see if the size is stamped on the headset cups or see if you can get a good enough caliper measure to get the right replacement. Using a 1 1/8 fork will get you a lot more options. But the shopping list is looking kind of long: fork, headset, stem, maybe handlebars (depending on their size and your stem). Ugh. Good luck, man.

wsteve464

Go here to maybe find the size you need.

https://www.canecreek.com/products/headsets/

https://blue.canecreek.com/headset-fit-finder

They have a setup for 49mm id head tube with press fit cups

If this doesn't work give them a call.

Miele Man

If you have or can get an old steel seatpost or length of pipe you can drill it and then cut it like this. Spread the resulting prongs and when you whack it with a hammer or whatever else you use there will be four sections bearing on the cup and the cup will usually come out really easily.

https://www.flickr.com/photos/738325...57660790238887

Cheers



Cheers

terrymorse 

Here's your photo:




If I were you, I wouldn't make the effort to convert a cheap bike like that to threadless. That's a lot of work and several new components. I'd just replace the fork with a matching threaded one and call it a day.

Your fork looks like this one on ebay, which also has a 1" threaded steering tube.

easyupbug 

Are you using ordinary WD-40 or WD-40 Rust Release Penetrant, there is a big difference in effectiveness.

jeffreythree

I have converted several bikes, road and mtb, to threadless forks. I would be doubly sure of the steerer size. A quick, cursory search showed a 25.4 quill stem on a Crossway, which is what goes in a 1-1/8" fork. Mongoose Crossway 250 (2012) Specs

bearpinata

1" threaded forks for 26 inchers are a dime a dozen here, but 1" threaded for 28/29 inchers aren't exactly common around here in Europe. The used market is also pathetic, with used prices starting at about 3/4 the cost of new, and sometimes higher than newhat I can find it for new online.
Threadless take-offs from factory setups are cheap and plentiful. Cheap bike or not, I'd rather invest in components that can be re-used later down the road instead of wasting money on dead-end stuff like threaded forks and quill stems.


Hers is the 150:
bikeroar.com/products/mongoose/crossway-150-2012/specs

They're obviously using the exact same frame for the 100, 150, 250, etc. The 250 is using a threadless Suntour NEX 4610 fork.
This one is definitely a 1" quill stem. You guys had me doubting so I triplechecked.

Dan Burkhart 

There is such a thing as 1" threaded headsets to fit a 34mm head tube, which is the size for a 1 1/8 headset, so I do not doubt the possibility that is what you have. If the internal diameter of the head tube is 34mm, you should be good to do the conversion. I have encountered exactly the same thing, and I'm pretty sure I still have the headset to prove it.

jeffreythree

Your link says: Stem: steel quill, 25.4. A 1" steerer would use a 22.2 quill stem. Your calipers measuring your stem is better than some website anyway. A quill stem fits inside, and is smaller, than the fork.

Geekage

I was thinking the same thing, but I think the 25.4 in the spec actually means the bar clamp diameter. OD of the stem is probably 22.2, but if it does measure 25.4, then yeah, it's a 1-1/8" headset.

bearpinata

Oops.
OK, the quill stem, calipered, is exactly 1" OD (25.4mm). I assumed this was a "1" quill stem" but I guess I was wrong

At least we're getting somewhere. So it seems I have a 1 1/8" threaded headset. What does this change for me?
Is 1 1/8" threaded and threadless pretty much the same except for the top cup?

Can just replacing the top cup allow me to use a threadless fork of the correct length?

cpach

1 1/8 is way more common so that's great! You could just change the top cup of the headset but complete headsets are pretty cheap--the main difficulty is if you need to remove the old headset and press the new one in, which is significantly easier with shop tools, but there are tons of threads/videos about making do with more improvised tools. You can find an inexpensive HS for less than $20USD that work fine.