Ibis Szazbo 69er
Ibis Szazbo 69er
This is the long story that started as a 1998 Ibis Szazbo frame that I purchased new from CBO on closeout after watching it for many months. I love this frame and believe it to be one of the greatest off-road frames ever designed. I built up the bike and have enjoyed many rides from our local city loops to our trips in AR, Mo, NM, NC, Col., Utah, Texas and Tenn. In the last couple of years, I began to read about 29ers and the 69ers. Then Trek made a 69er with a Maverick DUC 32 fork. I began to think about them on my rides. Wondering what a 29 inch wheels would be like until one day a new rider showed up on a redline 29er single speed. He was glad to show off his ride and let us all try it. Well, the 29s were awesome but the single speed not so. So I began to look at 29 and 69 data to figurer the change of putting a 29 front end on my old trusty steed. The data did not look good at first. Too much rake and the balance would be more equalivent to a downhill bike not a cross-country. So I put the project back on hold and work more on my other project a Mountain Cycle Zen with a super light Girvin carbon Crosslink shock. Now complete and rides awesome. I turn back to my first love the Ibis still wanting to breath new life into this unbelievable frame. I started reading more 69ers on forums like MTBR and soon took a hard look at the TREK 69er and its parts. The unusual design of the Maverick DUC 32 fork really caught my eye. So, I started reading in more detail about the fork and the front end. I almost gave up once and bought a single speed surly rigid off ebay but quickly realized that I'm too old and Arkansas is too hilly for me to be riding a single rigid. Then I looked at a Jamis 29er from JensonUSA but after reading some critical reviews I gave that up and turned back to my love for the Szazbo. After jumping back into the MTB forums a poster named Crawfishy had Idea that had never even crossed my mind email the designer John Castellano at
http://www.castellanodesigns.com/ . No kidding, In the information age connection is a click of the keys away. So I did. I really thought he might think this to be a stupid question on a frame that he had probably not messed with in years about adding a product that did not exist when it was originally designed. Turns out after a few days an email from mr.pivotless.
Glad your Szazbo has been treating you well. I recently went through all the geometry issues while designing the new Zorro, son of Szazbo. I presume you've checked it out? If not, see:
http://www.castellanodesigns.com/Zorro.html
I use a big spreadsheet to do all my geometry. That is because each geometry change affects all the rest. I use it for my new designs and for custom fitting. One of my customers called it the "CastroBlender". It calculates cockpit fit, center-of-gravity location, and front end trail numbers. To answer your question, I entered the old Szazbo geometry into the Blender, as well as a Szazbo with a 29" front wheel and 80mm travel fork.
The three main issues are: stand over height, center-of gravity, and trail.
1) Stand over height would increase by 1.5"--you can put a 3.25" block under your front wheel to see if that works for you and what that feels like.
2) BB would move up 1.3" and center-of-gravity moves up by 1/2" and back by over 2". My main concern would be wheelieing too easily on climbs. The front end may also wash out too easily when cornering. The CG is also high for the bike's wheelbase.
3) The frame angles slacken by 4.5 degrees. This increases the trail from 2.9" to 4.4"--a 50% increase. This will make the steering rather sluggish and may cause too much "wheel flop" on climbs.
Less travel (or rigid) would help with the geometry issues, but at the expense of a rougher ride. If you can find a Fisher Genesis 2 fork, it will knock 1/2" off the extra trail. Longer bars will help too.
Of course, your best bet from a performance standpoint would be a new Zorro! You're welcome to come by for a demo ride if you're near Santa Rosa, CA. I've addressed all the above issues and a few more too. But if you stick with the Szazbo, I've got shocks, pivot parts, and derailleur hangers (if yours is so-equipped).
Thanks, John Castellano
Turns out, John is a really nice guy and smart too. No wonder that he fathered such a great frame. So after reading this not so glowing review of my idea I had massive second thoughts of aborting this idea for fear of destroying the ride of my favorite ride. Then in a moment of weakness on ebay, I bought a used Maverick DUC 32 29er Fork and Wheel off a Trek 69er (the copper one) after placing a bid that I thought would never purchase it. BAM its mine. Holy Crap. So, my first thought was well that is a expensive mistake that will soon I will end up trying to re coop my money on ebay. Now that I have it, what will I do. First I will try this on the Szazbo. Then if that does not work I'll put the Szazbo back together and ebay a 29er frame or a Surly Pugsley but that is another crazy idea mine. Now I dove end to fitting this complex nontraditional fork to this frame. So back to the email and a quick note to the tech guys at Maverick. With new top crown everything went right together. Then came the rain and ice and destroyed my beloved Sylamo Trail the best public ridding in middle America. So I add an Avid 7 disc brake and had absolutely no were to test it. So first I did a shakedown ride in the local parks and cruised around the city of Batesville AR. Then after hearing that weeks after the worst ice storm in 10 years that the forest rangers at Sylamo still had all the trails closed and did not want any help cleaning them because of the extreme hazards of fallen trees. Frustrated without a proper test trail I ventured over to Craighead Forrest trail over in Jonesboro AR. These trails are fast and proved a great second test. Then I followed up with test three an urban city ride thru and around Lyon College. Now the conclusion of this novel I love this bike John was right I had to move the seat up and extend the rear shock length. This is a Monster I mean a monster truck of the bike world. The new stand over height is 80cm(77cm old) and the center of the bottom bracket to the floor is 37.5 cm (35.5cm) and wheel-to-wheel distance is 109cm(107cm) changed the shock to a fox vanilla fx 7.5 (7.25 old) I was also able to slide the seat up a bit and roll the handle bars forward to help correct the wheelieing effect not much change from the ibis with the Manitou black 120 but the massive crushing power of the 29-inch front wheel. This bike is blast. Thanks John
