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How to size a 29″er
29″ers seem to be generating a lot more interest in the mainstream press than in past years and, with the arrival of new models from manufacturers like Cannondale and Kona, many of you are going to have a chance to get a close look at these big-wheeled mountain bikes.
This article takes a look at the important things to look for when shopping for that first 29 incher.
Choosing a frame that fits
You will want to concern yourself with the obviously important measurements: top tube length and stand over height, but that’s not the end of the story.
It seems that there has been a trend towards designing hard tails with shorter seat tubes and severely sloping top tubes. This is true both for 26″ and 29″ hard tails, but is more commonly found with 29″ers. Some would argue that it’s because of the tire size itself, but the seat tubes on some 29″ers are just plain short. Shorter than they really need to be. Mass manufactured 29″ers tend to have this shorter seat tube to accommodate more different sized riders on the same frame size.
Take my 18″ Inbred 29″er, for instance. I have plenty of stand over clearance and I have to run a 410mm seat post to accommodate my leg length. If you are a long legged / short torso kind of person, you may find that this is a problem. Look around and try a couple of different designs to make sure you’re choosing the right bike for you.
After the seat height / top tube issues have been cleared, we can look at the next 29″er specific fit issue to deal with: handlebar height.
Handlebar height
Most complete 29″ bicycles come out of the box with riser bars. It’s the fashion du jour, but it’s not a good thing on a 29″er. Get that thing off of there and put on one of the new crop of flat, highly swept bars. They will mimic the hand position of a riser without the rise.
Since you are are dealing with a certain amount of extra height in the front end of a 29″er already, a riser bar will only make it higher (and probably way too high — unless you like being the Wheelie King!)
Pay close attention to the bar height from a past 26″ ride and try to get in that ball park with a new 29″er. You’ll get along with the handling much better that way!
Wheel clearance — for your feet!
Finally, the clearance between your feet and the front wheel needs to be addressed. If you are looking at a 29”er, it would be a good idea to bring along your cycling shoes and pedals when you head out for a look at the bikes. After having your pedals installed on the bike, you can then clip in with your own shoes and test for “toe overlap”. Toe overlap is a condition where your toe gets clipped by the front wheel as you are pedaling or standing on the pedals with the cranks level, all while while turning the handlebars sharply.
Obviously, you want to avoid toe overlap if possible. 29”ers tend to be more susceptible to this condition due to their unique front end geometry. Single speeders may want to be especially aware of this due to their proclivity for longer cranks.
I hope these three basic tips will help you if you are considering getting a 29″er anytime soon!
1. Posted by Ashwin | 10:38 am, 1 August 2006
Just a question: are the smaller sized 29ers more susceptible to toe overalp like smaller 700c road bikes are?
I kind of like the trend of steeply sloping top tubes. It gets the bars higher w/o having to resort to a huge stack of spacers or a steep rise stem. A similar trend has been showing up on road bikes as well which is good news for most normal people who don’t have the uber flexibility of pros. Semi-sloping top tubes (w/o the super short seattube of true compacts) combined with taller headtubes help a lot to get the bars higher.