A Question Of Making a 69er Out Of A 29″er
February 14th, 2008 by Guitar TedEditors Note: From time to time we get a question that we choose to post here. The answers given hopefully will help others and at the least, be somewhat entertaining.
Question: Can I put a 26 inch rear wheel in my 29″er? How will that affect the bike? Is it a good thing to try?
Answer: Well, three answers really. Yes. Negatively. Not really. Now, let me flesh this out for you.
The answer to your first question is “yes” only if you are dealing with a frame and wheel that is disc brake compatible. Rim brakes won’t work with such a change in diameter. Pretty simple there.
The second answer, “negatively”, is a bit more complicated. Let’s take a look at what really is going on when we pop a 26″er wheel in a 29″er frame. Think of the front axle as a pivoting point. Now imagine lowering the rear end of your bike without a rear wheel in it by pivoting the bike downwards around that front axle. Watch how the angles all become slacker and the bottom bracket gets a little closer to the ground. Yep! That’s what is going to happen to your 29 inch wheeled bike when you put a smaller rear wheel back there.
This causes several things, all of which I would deem negative, and I think most of the time, in most cases it is true. First the head angle gets shallower, causing slower steering and strange cornering behaviour. The seat angle changes, putting you further behind the bottom bracket and adversely affecting your seated pedaling posistion. It also will make seated to standing pedaling posistion maneuvers more difficult to pull off. Finally, your bottom bracket will be closer to the ground, increasing the chances for pedal strikes.
Now for the third answer, “not really”. It isn’t going to be a good representation of what a properly designed mixed wheel bike will do. At best, you will have a functional bicycle, at worst, it may be deemed unridable off road. Best to save up for a properly designed mixed wheel bike and leave the 29″er alone.
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what about doing this with a rigid 26″ fork/29″ front wheel on a 29″ frame?
bryant: While you might get lucky and retain your angles for the head and seat tube, you still are lowering the bottom bracket, which usually will result in more pedal strikes and depending on the bike, may cause you to “case” the BB on log crossings and the like.
All in all, I don’t see where going to all the bother to get a fork and a rear wheel to turn a 29″er into a 69er is a good deal. I would, if the situation called for being cheap, rather go for converting a 26″er over to a 69″er. The geometry issues still might be a problem, but using a rigid 26″ disc specific fork that is suspension corrected for 100mm fork should yield a fairly ridable bike for little coin.
I rode 40 some miles on my El Rey with a 26″ 2.5″ Nokian DH rear wheel when my XC 29er rear wheel blew up. The bike rode just fine and probably descended a bit better with the huge 26er. Definitely was more work climbing and the pedal strikes were annoying, but it was better than riding a 44lb 7″ bike on a 4000′ climb
I think a 650B on a full-suss 29er could make sense as a main bike, depending on the frame, but 26ers are too small to replace a 29er wheel permanently without causing some annoyances.
-Tony
I stand by my words, better try a 26″front wheel and longer travel fork. That’s a setup that might actually end up riding well, for certain types of riding. You keep most of the 29″ advantages for traction and speed, but add a long travel front with vast choice of front tires.
Other than that, stick to the excellent 29″ bikes being put on the market now. Fisher is quickly busting all myths that had negative things to say about 29″ers.
As long as it’s done well, larger wheels are better for anything resembling XC. Smaller, is worse. It’s laws of physics, and not too hard to understand. Harder is to get the full potential out of large wheels. Some manufacturers found out how.
1. I have often thought about putting a 26″ fork/wheel “reverse 69er” Hill Climber, because for the serious climbs here in the Seirra, but I was told going down would be seriously wack.
I just recently did an experiment with my 26″ Inbred, it has an On*One steel 26″ steel fork. and I actually fits my SpeedDiscs with the 2.2 Karma.
I have to say I converted my Vassago Jaberwockey to a 69er and love it. 2 years ago I won a Fisher Rig from Dirtrag and was very skeptical. I really wasn’t a 29er guy. I felt like a 29er was like riding a horse. Tall and awkward. So I put a 26″ wheel on the back and fell in love. I have yet to ride a carver but that is kind of in the works right now. Maybe the carver feel’s better and more resposive but the only thing I think it affects, is that you lose some clearance. I dont feel like the handling was compromised at all. I’ve ran it with a Reba, Vassago Pitch fork and a Pace carbon and I perfer the ridgid. I also feel like I can push a bigger gear with the 26 opposed to the 29 rear. I run a 38 x 16. (note: I’m almost 40 years old and going to try this combo at the Lumberjack100). I did try the 26 frame with a disk fork- suspension corrrected, but it didn’t feel as good as a 29 frame. I guess its all personal preference or may I’m just so screwed up I don’t relize the difference. Either way I think I will keep it.