You don't need to be an 'investor' to invest in Singletrack: 6 days left: 95% of target - Find out more
As part of a previous post here on the Forum about a full-size mock-up I made of a linkage suspension fork, the subsequent discussions included my plans to build a frame at The Bicycle Academy that would include some pretty unconventional geometry. That bike is now complete.
I believe that mainstream, contemporary geometry is requiring riders to support an ever-increasing proportion of their weight through their hands as a result of ever-steeper seat angles and longer front centres. While this is creating incredibly stable bicycles, it is also placing riders in a relatively unstable body position. My bike aims to place the rider in an Athletic Stance, allowing them to support more of their weight through their feet more of the time for greater rider stability. I believe that this is crucial to maximising my fun on a bike (If you are interested in knowing more then there is loads about this on my website - www.daveypushbikes.com).
A few people expressed an interest in seeing the bike once it was complete and so I’ve provided a couple of photos below. There are more images and plenty of details in my latest blog post as well as elsewhere on my website. But if you have any questions then please just let me know.
I don't spend any time pouring over geometry charts, thinking about suspension kinematics and the like, I just ride the bikes I have. You obviously take the design theory a lot further than most other riders, who'll just go with an angle set or offset bushing which is impressive enough, but you've also produced a really smart looking bike. I like it! Nice.
You had me at that handlebar.
you've chosen an interesting day to post that
Hi scaredypants. I know - April Fools Day and Easter Sunday! I've been trying to post something on my blog on the first of each month since January 2017. I wondered whether to hold off posting this, but the bike was ready so I thought that I'd just do it.
Apart from the socket HA that is how I have my inbred 29er too. Makes it closer to a BMX. Works well for me for trail riding.
Nice looking bike. The BA are ace aren't they. I was one of the original backers. Still got the t-shirt to prove it.
Looks like your design thoughts have travelled a similar path to Geoff Apps.
Weight on feet, short/zero length stem, high bars, etc.
His bikes are tremendously good at covering all types of terrain, in all conditions. Not fast , but fun.
I read your blog post for the 'full-moto' geometry, you have some interesting thoughts on frame geometry, especially the point you made about scaling stack relative to sizing.
Oddly enough some of what you have done makes me think of Jeff Jones ideas, he uses lots of bar sweep to bring reach back, allowing him to keep wheelbases longer and more stable, at the same time a rider can move their hands inboard to stretch them out for long flat cruising or grinding up climbs.
If course your bike is a different machine, aimed at having fun in the local woods as you say, I'm assuming climbing isn't a priority, that slack seat angle and short back end can't climb well... Right?
How is it in the air? I have to admit (back when I did such things more) I always though a shorter but steeper angled bike suited jumping a little better, but I am certainly not an expert...
As a tall lanky 6'6" I fully suscribe with your geometry - I prefer longer head tubes and like to 'ride' the rear wheel when standing Moto style. I have arms that bend at the elbow for when I want to weight the front and corner! Flat no rise bars and short head tubes coupled with long front centres just don't give you the option to weight the rear as much.
Spank do/did some mega high IIRC 75mm rise bars - I have some on my Jekyll.
I know sweet F A about geometry but that is one great looking bike, whereas Geoff Apps outputs are an abomination 🤢
Reminds me of this
The bike looks ace, have you had a chance to try it out yet? I've found my Geometron climbs brilliantly in the saddle,how does yours climb?
I learned to ride on a rigid bike with 120 mm stem so I got used to keeping my arms relatively straight to soak up the hits. To this day I still ride with very relaxed arms even though the suspension takes care of most of the bumps that I used to have use my arms for.
When I moved to a modern bike with slacker geometry my confidence took a big hit when I found my front end washing out as soon as I started pushing it where I used to two wheel drift when losing traction. Things improved once I figured out I have to bend my arms and really crouch down on the bike.
Your bike looks like it would let me get back to my old style of riding without the drawbacks of a long stem. Very interesting.
I know sweet F A about geometry but that is one great looking bike, whereas Geoff Apps outputs are an abomination
Not saying they look the same, or even that Geoff's bikes look great. But get over the looks and GA's bikes are very much a tool that fits a specific job.
tool that fits a specific job
Mountain biking with all the fun extracted? Live just outside Wendover so well aware of Geoff's input 😀
Definitely feels like a small wheeled Jeff Jones in concept. Nice work!
I’m similarly long-limbed and have found that less long reach but slack bikes suit my riding style better - and that although very steep seat angles climb well they don’t seem as good for me the rest of the time. On my full-sus, at 5’11, 430mm reach, 64 deg HA, 74 deg SA, with 50mm stem and 810mm bars feels near perfect.
I really like that OP, the mx bars look ace 🙂
Hi ajantom - I actually spoke (via e-mail) a few times with Geoff as I've been developing the geometry. There's not much he hasn't already thought about when it comes to mountain bike design. So it was really helpful to run my ideas past him. While his bikes are designed for a different type of riding, some of the thinking is very similar.
Hi cookeaa - I certainly read as much as I could about Jeff Jones' bikes while designing my own. He's one of the few people still asking questions of rigid mountain bike geometry. Although it's my understanding that his latest bikes have been primarily influenced by tandems and town bikes, so I think that it's fair to say that we've come at the problem from slightly different directions!
The back end is actually longer than it looks - I always think that the Paragon dropouts that I'm using have a habit of making the chainstays look a lot shorter than they actually are. The length of the chainstays was worked-out as as a percentage of the front centre. The proportions are the same as a Motocross bike because I wanted to get a similar weight distribution. So hopefully climbing will be acceptable, if not exactly the bikes forte.
I've only just finished the bike so haven't had a chance to ride it yet. Having said that, I'm definitely more of a 'wheels-on-the-ground' type of rider, so I'm almost certainly not the best person to comment on the bikes aerial capabilities. But once I've got a few serious rides under my belt I'll report back.
Yup, he's a really nice, helpful, and interesting guy.
Some people don't really get him or his ideas (see Dickyboy's comment above), and some seem to actually get quite offended that someone has the temerity to question orthodox MTB design. I'm not saying everything he proposes is perfect, but there's nothing wrong with a bit of experimentation.
I've been out riding with him a few times, and though we differ on some of our riding likes and dislikes (I'm less of an observed trials kind of rider) we both love a bit of 'off the beaten track' kind of stuff. Comments like the one above miss the point of his stuff totally - he has a lot of fun riding, just it's not about hooning downhill and winching up again. It's about the joy of getting through and to inaccessible places under your own steam.
Just needs a truss fork and bendy bars and its sorted.... Joking aside it looks very similar to a Jones and I had a Jones plus for a while and it was the most comfy bike I had ridden. It also descended like a demon. Im sold on the idea of shifting weight onto the saddle/pedals, with taller head tubes. Well done, I like that.
Think Jones work really well because of the multiple hand positions on the bars. Might be worth trying with a Jones bar
mtb geometry is all a compromise. it's nice to see someone is swaying away from long reach, slack head angled bikes that have become fashionable in the name of the ultimate stability over recent years and going in their own direction.
Although having said that I see nothing new or groundbreaking here and personally it's not geometry that appeals to me. But that's fairly common with most bikes designed by riders who admit to being "wheels on the ground " types.
Did you by any chance have (or really want) one of these in your childhood Oliver?
I can definitely see why my bike might get compared with a Jones - there's certainly very little else at this end of the geometry-spectrum. However, the differences between current, mainstream trail bikes from the likes of Specialized, Trek, Giant, Canyon, et al are far smaller, but the media tend instead to focus on a degree here or 10mm there. By contrast, the difference between my bike and a Jones is quite large.
Jeff Jones seems to have very different ideas in terms of fork offset / trail, so adding one of his truss forks would radically change the handling (even if the fork was corrected for AC length). As for the handlebars, I've always struggled to get on with the amount of back sweep that something like a Loop Bar has (I know lots of people rave about them), plus it would make the reach to the bars too short with the stem length that I want to run.
It looks like your setup gives you an effective stem length of zero, which is similar to a typical Jeff Jones setup. You have to run a longer actual stem with the loop bars because of the huge backsweep but the forward offset of the grips vs the steering axis remains around zero.
It’s this forward offset of grips from the steering axis (what I call effective stem length) that determines that aspect of the steering feel, not the actual stem length.
Jeff’s bikes are designed around longer offsets and lower trail - I think it’s 70 deg head angle and 55mm offset on the SWB and 67.5 HA and 76m offset on the LWB. But a similar tall stack and short reach approach to rider fit.
I've had similar thoughts on geometry as this, but l do like longer reaches - bar heights and stack should be getting taller to compensate for the longer reach. I personally feel we shoukd be running even shorter stems than 35mm as well, to reduce the reach but keep the length.
Motos are very long in comparison to MTBs, no doubt if you slammed the stack heights on them you'd end up with very long reaches.
Interestingly, Honda tried going with shorter front centres and longer CS length on their MX bikes a while back, but canned the idea.
I recently measured the wheelbase of a few MX bikes (at work).
And found that modern long reach long wheelbase mountainbikes. eg. Geometron. Are actually getting longer than motos.
Really?
The wheelbase of a Yamaha YZ450 is close to 1500mm and more than 4 inches longer than the XL geometron.
Yeah really.
These bikes were only 125s. their wheelbases were around 1350mm. Similar wheelbase to the second longest geometron.
Yeah, having said that - I bet those 125s aren't being ridden at a much higher average speed than the geometrons that are being pushed by quick riders on descents. Then they have mass to aid stabiluty, where as pedal bikes don't....