Converting Forks From 1 and 1/8" Steerer to 1" Steerer

[The Mighty Volt]

Hi Folks.

Yesterday I stuck a set of Zoom Endura Forks onto a Giant BMX frame and was quite surprised how well they fitted and how well they looked. Unfortunately the forks are seized and are useful only for measurement purposes. The Zoom forks are stamped on the tube as being 25.4mm, which is basically .4mm over 1", that is to day, they are 1" tube forks, for all intents and purposes. They pitch the bike forward at a nice angle, and look well suited to higher-speed applications. The head of the BMX frame is bullet-proof, so I am not worried about stress or fractures over time.

There seems to be a total lack of 1" steerer options in the MTB suspension department, with everyone going for 1 and 1/8th inch variants these days.

I can buy forks with the 1 and 1/8th inch steerer...............can I then remove the steerer tube and replace it, or do I need a dedicated 1" tube for a dedicated 1" set of forks???

Can some adjustment be made to get a 1" steerer into a set of forks which came with a 1 and 1/8th inch tube.

There are forks out there for sale, designed for a 1" steerer, which come with no steerer tube, does anyone know then how much time and effort is then required to fit a 1" tube??

 

[John in CR]

1 inch = 25.4mm not 25mm or 25.8mm

 

[The Mighty Volt]

1 inch = 25.4mm not 25mm or 25.8mm

Well.......over here there 2.5cm in one inch, 12 inches in one foot, and therefore 30cm in one foot, and 10mm in one centimeter, which is plain Latin.

That means that there would be 25mm even in one inch.

Anyways its not a major sticking point.

25.4m means one inch, one way or the other.

Cheers.

 

[FMB42]

I think Marzocchi and Zoom(?) used to offer steerer tubes for converting a 1-1/8" fork over to 1". The Marzocchi conversion tube required a press fit installation while the Zoom was a "bolt on" deal.

Not sure if these are still available though...

 

[Lenk42602]

RST sells forks without the steerer tube - just the crown, fork tubes and stanchion legs. You have to buy the steerer separately and can do so in 1" and 1-1/8" sizes.

Len

 

[amberwolf]

There is a thread, if I can find the link, where exactly this was done--converting from the larger to the smaller. IIRC, he used a ring cut off of the old larger steerer to make a spacer for the new smaller steerer. It is what I planned to do on a fork I have here, but since that time I ended up with a different frame that has the larger size headtube, that is now part of the new bike.

Well.......over here there 2.5cm in one inch, 12 inches in one foot, and therefore 30cm in one foot, and 10mm in one centimeter, which is plain Latin.

While the latter is correct, and the second, the first and next-to-last are not quite. it is indeed 2.54cm = 1in, and 30.48cm = 1ft. (unless you are using Clarke or Cape or Sear feet, AFAIK, in which case it is very slightly different, according to things like the Quad-Lock converter
http://www.quadlock.com/about/unit_converter.htm
and Wikipedia
http://en.wikipedia.org/wiki/Foot_(unit)
http://en.wikipedia.org/wiki/Inch ).

As a side note, in Baden, currently part of Germany,
http://en.wikipedia.org/wiki/Baden
there was a time when the foot was defined as 30cm.

 

[John in CR]

There's still enough old steel frames in use down here that the steerer tube swap is common. One of the LBS's nearby gets it done for $8-9 including the new tube. Apparently the machine shop presses out the steerer and pops a new one in. I've not had it done because having some local yahoo mess with that highest stress and risk connection on the bike doesn't sit well with me.

 

[The Mighty Volt]

Well gentlemen, thanks for all the feedback.

I just spent the evening sliding a nasty 25.4mm ZOOM fork, and a beautiful one-and-one-eight Marzocchi 44 RLO fork in and out of the head-tube of my Giant BMX frame.

For the life of me, I cannot find a difference in play, slackness, etc between the two.

I know it is only mm, but the rigid fork which came with the bike appears to be as good or as bad a fit in the head-tube as either of the other two forks mentioned.

Just what sort of risks am I running here if I fit the marzocchi forks?? The plan was to use the basic stem, tighten it down, do the measurements, drop in a star nut and tighten that down too after the forks had of course been cut to the appropriate length.

None of that seemed any tighter or any looser than the standard rigid forks and a lot of the components appear to be interchangeable.

The height of the bike is changed a bit and the geometry is changed a bit but not drastically.

Unfortunately I am waiting for a new SD card so no photos yet, I really want to add front forks to improve the bikes handling at top speed and also give me the chance of selling the bike on at some later stage.

Cheers.

 

[amberwolf]

BTW, I finally found the thread I was thinking of, should you ever need to do the change:
http://www.endless-sphere.com/forums/viewtopic.php?p=232106#p232106

 

[John in CR]

Well gentlemen, thanks for all the feedback.

I just spent the evening sliding a nasty 25.4mm ZOOM fork, and a beautiful one-and-one-eight Marzocchi 44 RLO fork in and out of the head-tube of my Giant BMX frame.

For the life of me, I cannot find a difference in play, slackness, etc between the two.

I know it is only mm, but the rigid fork which came with the bike appears to be as good or as bad a fit in the head-tube as either of the other two forks mentioned.

Just what sort of risks am I running here if I fit the marzocchi forks?? The plan was to use the basic stem, tighten it down, do the measurements, drop in a star nut and tighten that down too after the forks had of course been cut to the appropriate length.

None of that seemed any tighter or any looser than the standard rigid forks and a lot of the components appear to be interchangeable.

The height of the bike is changed a bit and the geometry is changed a bit but not drastically.

Unfortunately I am waiting for a new SD card so no photos yet, I really want to add front forks to improve the bikes handling at top speed and also give me the chance of selling the bike on at some later stage.

Cheers.

The problem is fitting the tube bearing races in the headtube. Maybe you got lucky and the frame was made for a 1 1/8th fork, but the manufacture wanted to cut corners and use cheaper 1" forks, so they installed some adapting tube races to accept the 1" bearings. Just sliding the fork in and out doesn't tell you anything. You have to fit the bearings. If the bearing races fit the head tube then lucky you.

 

[The Mighty Volt]

Thanks John. That figures all-right. I'll get the pertinent bearings and see what happens.

 

[AussieJester]

Thanks John. That figures all-right. I'll get the pertinent bearings and see what happens.

you wont get the bearings in the cups been there done that, you will
have to change the forks tube no way around it unfortunately...well, unless
you cut off the frames head tube... or at least weld some tubing thats 1 1/8
on the top and bottom of the existing frames head tube so you can fit the cups
that hold the suitable bearings for the 1 1/8 fork

KiM

 

[john7700]

There are a lot of options out there. Here is just one http://www.amazon.com/RST-Suspension-threaded-steerer-160mm/dp/B000FIFDO0 or you can buy a fork with out a steerer and put a 1" in.

J

 

[The Mighty Volt]

Thanks John. That figures all-right. I'll get the pertinent bearings and see what happens.

you wont get the bearings in the cups been there done that, you will
have to change the forks tube no way around it unfortunately...well, unless
you cut off the frames head tube... or at least weld some tubing thats 1 1/8
on the top and bottom of the existing frames head tube so you can fit the cups
that hold the suitable bearings for the 1 1/8 fork

KiM

Cheers Aussie. You going to clean up in New Zealand next month???

 

[AussieJester]

Might as well give the cup to the Wallabies right now and crown them World Champions, it will be a mere formality playing the games Mighty Volt, a 'meeere' formality (of course saying that, I have all but guarenteed they will be knocked out n the first round HAHA)

KiM

 

[The Mighty Volt]

Nah, Oz will walk it I am sure. Ireland might as well stay home. England for the Semi's, Kiwis to choke at the first opportunity. 1987 was a freak. Or should I say frock!