A Hot Topic: DH 29er v's DH 650B

Photo: Adam Marsden Photography

My name is Jack Reading and I run and race for Nicolai Bikes factory race program, One Vision Global Racing. I've been riding mountain bikes since I was tall enough, and I've been racing World Cup downhill since 2010... when my racing career started did I ever think I'd be testing my 27.5/650B race bike against a new prototype 29er version? Absolutely not! Like many I get completely absorbed by the here and now, so I was convinced 26 inch was the never ending future. How things have changed! After the Fort William world cup this year I decided I was ready to start the 29er DH journey myself, so I made the phone call to Nicolai to start working on a prototype race rig for me. The timing of this was for two reasons: 1/ more and more guys are switching out to 29ers and we're seeing huge improvements in their results. 2/ More importantly, I had started riding Nicolai's G15 29er trail bike in May this year and I instantly loved it and felt the wheel size suited my riding.


Photo: Adam Marsden Photography

This prototype arrived the week before the La Bresse world cup which was the final round of the series. Just in time for me to test it on the world cup stage before the off season. Coming into the race on a high after qualifying 15th in MSA I knew I was riding my 650B bike well, so I was excited to get a comparison. I did the first three practice runs on my current 650B bike to learn the new track and get up to speed. I then switched to the 29er and after two runs I knew I wouldn't be switching back. Three factors stood out: 1/ increased stability at speed. 2/ I wasn't losing speed over rough sections/holes. 3/ increased front end traction when I turned hard. I went on to finish 21st in finals, my best result of the season and only my 12th run on the bike ever. However I hadn't done any back to back timed testing. So after being home a week I headed to Revolution Bike Park to do exactly that.


Photo: Adam Marsden Photography

Going into this project I am under no pressure from sponsors, specifically Nicolai Bikes. My interest is 100% based on the speed and performance of the bikes, so it is very easy for me to do completely objective and unbiased testing of the two versions, and give you honest feedback. This doesn't mean that what I prefer and am faster on would be the same for another rider, but my feedback will give you some idea of the things you're looking for when trying to make the decision yourself.


Photo: Adam Marsden Photography

The test track I used at Revolution Bike Park was the 'Farr Side' trail into the lower section of 'Ghetto'. This is great for DH testing because it is flat out fast and has lots of different types of terrain to challenge both bike and rider. Fast sections, jumps, steep sections with some big optional lines, flat sections to pedal and some really rough parts. It was dusty dry and running fast for testing which was ideal. I started on the 29er...



Photo: Adam Marsden Photography

I did 7 runs on this bike, to make sure that when I did my timed run I was properly up to speed. If you do a timed run too early and then switch to the other bike, your speed can naturally increase as you learn the flow of the trail and get progressively faster, making the time comparison inaccurate. By my 7th run I new I was at my limit on this track for the day. The bike felt so smooth and stable all day and in all 7 runs I don't think I had one 'nearly' moment. The timed run on the 29er felt so fluid I almost felt like I wasn't trying and the bike just motored through everything, leaving me feeling really fresh at the bottom. The time was a 2.39 and I felt like I could replicate the run over and over.


Photo: Adam Marsden Photography

Switching back to my 650B bike, and somewhat reluctantly as I was having so much fun on the 29er, I wondered how it was going to feel. I hadn't been back on the 27.5 wheels since those first three practice runs at the start of the La Bresse weekend, and they looked tiny as I pulled the bike out of the van. Open minded I headed off to get back into the bike. I planned to do 2 runs to adjust, then a timed run. After the first run I made a couple of adjustments to the bike to get it feeling how I wanted, and after another I then felt ready to do the timed run. One thing I did find was that during these two warm up runs I had a number of near misses, and on the second run I got unsettled to the point where I actually had to miss one gap line I'd done comfortably every time on the 29er. The bike just didn't feel as settled and stable without the big wheels.


Photo: Adam Marsden Photography

The timed run felt similar to the first, except I actually felt like I was going faster than before, and that I was more on the edge. The bike felt slightly more lively than the 29er, in the sense that at any moment things could go wrong and I'd be on the ground wondering how I got there. I never had this feeling on the 29er, which had me wondering if I wasn't riding the bike to its full potential and taking it too easy on the first timed run. When I stopped the clock I got a shock when it said 2.41, two seconds slower than the 29er! I was convinced the second timed run on the 650B was faster. It just supports the theory that what feels fast isn't always fast.


Photo: Adam Marsden Photography

So there we have it. The prototype 29er took the win! In terms of the bikes, the geometry of the G29 prototype is as similar as possible to the existing G19 650B version. The wheelbase on the 29er is longer, sitting at 1400mm compared to 1318mm with the large G19, and the chain stay swing arms are slightly longer. The 29er has reduced rear travel at 180mm, compared with its 650B counterpart that boasts 193mm. The next step in my testing is going to be working with Nicolai on a 29er version with as much rear end travel as we can get, and I want try it slightly smaller in the wheelbase and reach. I feel that the stability I gain from the 29 inch wheels, will allow me to reduce the reach and wheelbase slightly to make the bike more manoeuvrable, but still give that stable and smooth ride at speed.


Photo: Adam Marsden Photography

The final point I want to make which I feel is really important, is about fun. I have heard so much talk over the last few years that the bigger you make the wheel size, the less fun the bike becomes. That has not been my experience. I like going fast on my bike, whether that be my trail/enduro bike, or my DH bike at a race or on an uplift weekend. I've found that the 29 inch wheels give me more grip, more stability, and a faster rolling speed, all together making me feel like I can go even faster and feel more in control while doing it. Now to me that isn't a bad thing at all! If your fun is like mine, revolving around speed and going as fast as you can on a weekend, whether that's at the races or trying to drop your mates at the local, give the bigger wheels a try and make your own mind up. You never know you might be surprised like I have been.


Photo: Adam Marsden Photography

However all that being said the current world champion Loic Bruni isn't a fan of 29 inch wheels at all and that's no secret, so it's obviously not for everyone. I am a taller rider at 6' (182cm), and I do believe there is some logic to the theory that a smaller rider can feel out of proportion using the bigger wheels. You wouldn't expect to see size 5 feet on a guy over 6' tall, and you don't often see size 12 on a lady 5'5", and I feel wheel size on a bike can be looked at in a slightly similar way. Again though that clearly isn't always the case, with Loris Vergier being a smaller rider at 5'9", and he won a world cup this year on a large V10 with 29 inch wheels. I hope this has been informative, with the main message being that if you're interested, get out on the trails and give it a try for yourself before you buy your next new bike! Happy trails everyone.