Hiya I bought a set of wheels for my 97’ GT idrive got to be 4 years ago, but never got around to building the bike up, anyway I have decided that I may get on with it , but I can’t for the life of me remember what the axle should be , or if I can adapt them to a normal sewer, the hole is 19mm ,

19mm seems odd but it's nearer to 20mm than it is anything else, so I'm going for that. Not much 20mm stuff about these days though.

Ok, I used a vernier to measure the hole so prob is 20mm , what would I need ?

what would I need ?

20mm through axle but are your forks designed to accept a 20mm axle? It really was the preserve of long travel / DH type stuff.

what he said
However you can get 20- 15 mm adpters on ebay and 15 mm to QR about £5 depending on which you want

https://www.ebay.co.uk/itm/20mm-to-15mm ... Swd3pdZeMT

20-15


QR

https://www.ebay.co.uk/itm/Front-wheel- ... SwYfBc-FLl


I use both of those adapters
Its a faff but dooableto change size though a 20 mm fork would also work

20mm to 15mm would give you boost spacing though as 20mm is designed around a 110mm axle.

Knowing what hub it is is more useful as we can say whether it can be converted properly.

All my boost forks[ 2 suspension and one rigid] are 15 mm and only my old 26" pikes are 20mm

Is it really a Boost thing? as stu said i thought it was from DH days and the first nonQR forks were 20mm but 15mm quickly became the new standard
You can convert any 20 mm hub [boost and non boost] as long as it has end caps [ie is correctly spaced befoe you start] as I have done it with two wheels

The 20mm forks were 20x110 so the same width as boost is now.

15mm are 15x100 so easy to convert to qr with the adapter.

I had some 26" pikes that were 20mm and u turn so I could adjust the travel as well but they were worn out rocked under breaking so I swapped them for some fox 32s which were flexy enough to not be much better

same pikes still working on my kids bike and it is not Boost. Boost was not a thing in 2004

Of the 15mm I have two sets that are not boost and two that are boost
I think 15 mm is the new standard and the boost thing is not related to axle size [ though at some point it may have been ]
and a 15 mm non boost dynamo hub [and a QR one in highly fashionable 26 - must be worth pence that wheel Not sure when I last used that one tbh.

A handy link from Stans that explains the difference between 110mm x 20mm and 110mm boost hubs:

https://www.notubes.com/news/say-what-t ... explained/

To expand on what sean_iow said:

The axle diameter is nothing to do with boost or otherwise, it's the length that matters.

20mm is a 110mm axle, not boost.

15mm is a 100mm axle.

15mm boost is a 110mm axle.

So if you reduce a 110mm 20mm diameter axle down to 15mm diameter you are left with a 15mm boost length axle. You would then need to offset the rotor like in a Hope Pro boost kit to get boost spacing on the brake.

In short: You can convert any 20mm hub to 15mm boost using those inserts but only hubs with specific adaptors (like Hope and Novatech) can size down conventionally. As I said in the first place, knowing what hub the OP has is key to knowing whether they can be sized down or not.

And 20mm was the standard long before 15mm, mid 2000's every other fork was 20mm, QR was the preserve of XC and "All Mountain" (but not Freeride). 15mm is a relative newcomer.

There is a link above you to a 20x 110 non boost axle so 20 mm x 110mmm may or may not be boost and i have some 20mm forks that are 100mm axle size and 100 mm hub. Secondly hub width wont tell you if it boost or not -though that the length does not say for certain is news to me
I dont think we have helped bring any clarity here for a confused OP but for that i blame the industry and its quest for standards.


OP you will need to measure the width of your hub if its1 00 mm then its a 20 x 100 and you will need to adapt to 15 mm or QR as there will likely only be DH forks it will fit

if its 100 mm then use the stands link to measure the hub and flanges/end caps
Boost =get someboost forks
110 x 20 non boost = no idea probably someDHforks or spacers tomove tedisc which willbe sub optmal IMHO- though I have never done this

My conclusion is it takes a lot of us to work out what the stadards are then we realise there are none !

Thanks for replies, mmm, it’s not very straightforward is it , so........ on the 8th Feb I’m booked onto a wheel building course, I think my best option is to maybe change the hub to a normal QR or thru axle that will fit the forks that I get for that bike ,
Thanks again fellas !

Lazarus wrote: ↑Fri Jan 24, 2020 10:35 am There is a link above you to a 20x 110 non boost axle so 20 mm x 110mmm may or may not be boost

Except 20mm boost is a 2 year old standard the hub ozboz has is over 4 years old. It is certainly not boost and I would stake the cost of the wheelbuild on that.

i have some 20mm forks that are 100mm axle size and 100 mm hub.

Unless you have some wierd ass Maverick or proprietary standard then no, you don't, it's 20 x 110 like everyone else.

I dont think we have helped bring any clarity here for a confused OP but for that i blame the industry and its quest for standards.

With all due respect sean_iow and I have been quite clear, you keep contradicting what we say.

OP you will need to measure the width of your hub if its1 00 mm then its a 20 x 100 and you will need to adapt to 15 mm or QR as there will likely only be DH forks it will fit

Again, there is no such size as 20 x 100. I've seen sites referencing this but they are wrong, entirely and utterly.

if its 100 mm then use the stands link to measure the hub and flanges/end caps
Boost =get someboost forks
110 x 20 non boost = no idea probably someDHforks or spacers tomove tedisc which willbe sub optmal IMHO- though I have never done this

This wouldn't work anyway, as said before if you used the linked 15mm inserts on a 20mm hub you would still have a 110mm axle which, in 15mm diameter is boost! Boost hubs have the rotors outboard of a standard hub so cannot be sized down (whereas a standard hub can be sized up using shims).

If you don't believe me:

https://www.bikeradar.com/features/a-gu ... standards/
https://www.sheldonbrown.com/frame-spacing.html



@ozboz could you please tell us what hub you are running so this can be put to bed once and for all?

Again, there is no such size as 20 x 100

and again I have a set that are 100 x 20 mm so clearly they do exist - Hope did 20 mm adapters long before they did boost hubs There was a large travel Bomber fork as well as my mate had them-this was before i had pikes mind early 2000's.
I bough tthem of TON but he will have so many forks he wont remeber them

I see no value in you telling me forks I have dont exist.
PIke 454 U turn
If you want i can send you some pics with a tape measure and a boost hub not fitting and a standard one fitting - seriously what do I need to do to convince you forks I own exist?- or you could just believe that I know what size my own forks are have had for over a decade-

Here is a link for the rockshok 20 x 100 mm mxle that does not exitst listing models it fits.

https://hollandbikeshop.com/en-gb/sram/ ... for-32-mm/

I dont want to argue and I dont know how else to convince you its real than this reply

No offence you are wriong trust me i have the evidence for over a decade.

That wheel is a Sun-Ringle Inferno 27, I got it off eBay to replace the one on the GT , the rim had worn out , I dug out this photo of the bike about 2013-14, as you can see the forks are Marchozzi Bombers and if you look ‘ at the hub you can make out ‘20’ and a large skewer cap, i remember now it had QR 20 sticker on it , so the wheel would have fit ok , but..........it is a disc brake hub , my idea now is to get a disc fork , I cannot find the the axle , I didn’t ride the bike for long so never took much notice of what it did or did not have, when I discovered the wheel was incorrect , the bike was abandoned until now,

Ozboz - depending on the exact hub model there may be an adaptor

https://www.bike-components.de/en/SUNri ... it-p49385/

Unfortunately your photo didn't come through but QR20 is 20 x 110mm as said. You can use any Marzocchi axle in there, it's just the QR ones are quicker to undo than the ones that screw together. If you intend on using those forks then you will need to use 20mm. I may or may not have a spare QR20 axle kicking about, from the looks of it they are not particularly easy to get a hold of (like most QR20 bits) so if I do have one I'd be happy to sell it. Actually wait, if it's a non-disc fork check for two threaded holes down where the IS mount would be, if those holes are there then you need a Z3 caliper mount which would allow you to convert them.

One of these: https://www.chainreactioncycles.com/mar ... p-prod2026

Again, like rocking horse poo so maybe you are better selling them on rather than trying to track down parts someone is only going to fleece you for.


Lazarus, that axle says nothing about being 100mm and I have already posted my proof. I get the distinct feeling you're just bamming me up at this point, you're not Junkyard from STW are you? Please take your trolling elsewhere as it's not funny and you're crapping on a thread started by someone seeking help by feeding him a load of nonsense and misinformation.

>insert panda here<

Ah okay, that's a Marzocchi hub so converting is a fat nope . Forks look like Z3 QR20's assuming those are black caps that do nothing on top. Good news is an enthusiast/idiot (delete as applicable) would pay a decent amount for the hub especially if its the one with rotor mounts and the forks probably wouldn't do too badly if you decided to get rid as well.

That not withstanding, with an axle and brake mount there's no reason not to keep them. They were good forks and easy to keep in good shape.

That wheel with hub has long gone, so that’s it I suppose , it did not have a rotor adapter either , so ,..... I’ll probably go for a hub that will suit the forks I get for it , I’ve got two idrive frames, my favoured one does not have a disc mount on the rear , so that’s a thing for another day so as for now it’s shelved again , thanks for the help ,most appreciated !