Converting a 26er into a 96er?

[Brian McVickers]

Well the front fork on my 26er mountain bike is finally on its last leg.
The fork is an old Rock Shox M21 Air/Oil system that they don't eve have parts for anymore. Perhaps it could be rebuilt but every time I have talked to a bike shop about it, and I even talked to RS about it once, everyone raises an eybrow and snickers at what a lost cause it woul be to mess with such an old shock.

So, faced with having to replace the front end I figure it would be the perfect time to trade up to a 29" wheel in the front and make what they call a 96er, a 29" wheel up front an a 26" wheel in the back. Some also call it a 69er.

Do we have any bike mechanics around here who could help with figuring out the specifics?

I figure I'll need a front fork that will accomodate a 29" wheel, and a 29" wheel. Anything else needed for the conversion?

Thanks
Brian:bike_rider:

 

[1speed]

If you try to run a 29" suspension fork and wheel you will end up with a "chopper". A 29er wheel will not clear the bridge on a 26" suspension fork. The only way to do it is with a 26" rigid fork with a disc brake and a 29" front wheel. It will work, but most of the time you just end up with a funky handling bike. I tried it with a Salsa Ala Carte I had and it just didn't feel right.

My advice would be to either buy a frame built specifically for this application or pull the trigger on a 29er. I personally will not go back to 26" wheels.

 

[chris_the_wrench]

Well the front fork on my 26er mountain bike is finally on its last leg.
The fork is an old Rock Shox M21 Air/Oil system that they don't eve have parts for anymore. Perhaps it could be rebuilt but every time I have talked to a bike shop about it, and I even talked to RS about it once, everyone raises an eybrow and snickers at what a lost cause it woul be to mess with such an old shock.

So, faced with having to replace the front end I figure it would be the perfect time to trade up to a 29" wheel in the front and make what they call a 96er, a 29" wheel up front an a 26" wheel in the back. Some also call it a 69er.

Do we have any bike mechanics around here who could help with figuring out the specifics?

I figure I'll need a front fork that will accomodate a 29" wheel, and a 29" wheel. Anything else needed for the conversion?

Thanks
Brian:bike_rider:

I've never rode one, but Trek dropped the 69'er model from this years line. maybe it just didn't catch on?

You have to remember that going to a 29" front wheel with a suspension fork is going to drastically change your headtube angle making it very slack. Your starting out with a frame that was deigned around an 80mm fork to begin with, so your really going to feel the effect. If it was me and I wanted to experiment with this conversion, I would put a 29" rigid fork(lower crown to axle length than a suspension fork). So you would need a fork, wheel, tire/tube, your old headset fork race, and your probably going to have to upgrade to a front disc brake at this time if you don't have one already.

Hopefully this old frame you have is 1 1/8" steer tube also! I've seen plenty of 1" mag 21's roll through. If it's 1" steer your fork options have been cut by like 99%.

If you walked into my shop with this situation I would, most likely, try and convince you to go with a replacement 26" fork that fits with your bike.

-Chris

 

[bunduguy]

As mentioned, first issue will be head tube diameter. 1" gives very few options. Apart from that, there are no major issues, except for longer brake lines! As also mentioned, the head angle will vastly increase making way slacker, and slower handling. BUT, depending on your current fork, you could go with a 29er fork with less travel, to compensate, and reduce said head angle. Problem is, most older forks would only have been 80-100mm, meaning you're already at the lower limit of current fork travel standards.

so besides a different for, you'll also need a wheel!

Probably your best bet, for little money, is to just get a rigid 26er fork. Or, go onto PRICEPOINT, and find a blowout fork that may be a couple seasons old, but brand new, and will do a great job for little $$$.

I have a 140mm on my Ibis Mojo, and considered running a 100mm 29er fork, that would have kept the head angle much the same, and in essence, also keeping the same travel. But decided against it because you have to carry 2 different tubes (unless you run tubeless, in which case you still carry tubes for emergencies:sombrero

 

[Christophe Noel]

The best quote I ever came across regarding the 69er bike was, "The front wheel writes checks the rear wheel can't cash."

The smaller rear wheel sorta makes sense for some full suspension bikes, but ultimately I think the odd-ball wheel thing is losing favor...again. The Cannondale Beast of the East 24/26 bike of the 80s croaked long ago for the same reasons.

Regarding a conversion, as others have said, you'll just end up with a bike with funky angles. It would probably ride nice once you got it up to about 60mph.


By the way, as I recall, a Mag 21 was never an 80mm fork. That would have been "long travel" for that period. I'm pretty sure that fork was only 63mm of travel.

 

[Brian McVickers]

Ok so that idea may not work to well.

How about rebuilding the Mag 21 with bushings or springs. Canthat be done? Or am I better off getting a more modern set of shox?

 

[Christophe Noel]

Ok so that idea may not work to well.

How about rebuilding the Mag 21 with bushings or springs. Canthat be done? Or am I better off getting a more modern set of shox?

As others have said, finding a good 1" steerer fork will be a challenge. You're probably looking at a rigid fork at this point as most of the rebuild kits for these forks are long gone. Look at it this way, rigid is coming back! Just start giving guys with suspension forks an obvious look of pity, and you can pull of the most rigid of rigid forks.

 

[dieselcruiserhead]

Here is my goofy-*** attempt at my first 69er. You can see how weird it is. This is a few years ago and me messing around, but this was a 110 fork so not too tall..

I also rode the Trek 69er designed that well and it was great but again it felt weird having that little tire in the back. IMO 26er and 29er are a far cry from each other, 29er mows everything over and rips, 26er to me feels every bump in trail..

650b fits in most 26er forks and rolls like 29er but smaller.. That is what I would do.. 650b is fully compatible with both 26er and 29er and lightly affects the geometry as well...

 

[chris_the_wrench]

By the way, as I recall, a Mag 21 was never an 80mm fork. That would have been "long travel" for that period. I'm pretty sure that fork was only 63mm of travel.

Your right. I was thinking 63mm but typed 80mm(subbed in a sid in place of a mag21).

FWIW I was digging through the old shock parts bin at work the other day and we have a mess of old NOS rockshox parts... Collectors items! Here they come ebay. :wings:

-Chris

 

[chris_the_wrench]

Ok so that idea may not work to well.

How about rebuilding the Mag 21 with bushings or springs. Canthat be done? Or am I better off getting a more modern set of shox?

I might have all the parts you need to rebuild it, but you'll need someone with the knowledge and the proper bushing remover and installer tools. It's, probably, not worth the labor charges. We usually sell people with old 1" steer tube forks a rst replacement for about $150 with labor.

Do you know if it's a 1" or 1 1/8" steer tube? Threaded or unthreaded? Length of steer tube? I have a handful of older forks that could work for you as an ok replacement.

-Chris

 

[Brian McVickers]

Thanks

The frame is a Trek 7000 ZX.
Aluminum from around 1992.
I think it is a 16 or 17 inch frame.
I just know it is small for me at six feet tall but when I built it it was for narrow east coast wooded single track, small frame, narrow bars....:bike_rider:

I'll see if I can get some measurements.

Regards,
Brian

 

[Christophe Noel]

FWIW I was digging through the old shock parts bin at work the other day and we have a mess of old NOS rockshox parts... Collectors items! Here they come ebay. :wings:

-Chris

Speaking of collector's items, I found some Dura-Ace STI shifter covers in my tool box. These were just the little round plastic decal thingies that went on the front of the STI levers. I sold a pair of them for $80. They were probably $5 each in 1991. I also sold a brand new pair of Modolo Speedy brake calipers from 1987 (never used - in the box) for $166. Nuts.