[Closed] MTB Geometry - Seatpost Angles?

Sounds like your frame is too small - why did you go for that one?

Mike - two reasons:

1. Vassago don't make an XL and 29+ frame options are a bit thin on the ground.

2. I am an idiot.

However, even if the ETT/ reach were a bit longer I would still be perched way behind the BB with the seatpost extension I need.

The back ends of most bikes are similar and don't change with bike size, so having your arse over the rear axle would happen on other bikes and sizes with 73 degree seat angles (unless the Vassago has a very short chainstay).  If you are getting that pushing back on the pedals feeling it may be that the front end geometry is pushing your torso too upright.

Andy - it sounds like you might benefit from going for a custom frame, I think you're going to struggle to get the fit you're looking for with your current one...

Get your saddle position correct so that you're sat where you want to be fore/aft on the bike, then work out what you need to do to get the cockpit correct.

How does it currently feel when stood up on it?

That does seem like a very short frame - in comparison my medium Soul is longer...

Is this bum back position just a result of modern mtb geometry that I am not used to?

Modern longer/slacker geo generally pushes the rider forwards relative to the BB which then lengthens the TT and pushes the front wheel forward, then balanced so you're still sat in the middle of the bike by lengthening the stays to match - so exactly the opposite of what you're describing. Looking at the geo  (I presume its a jabberywocky?) I'm not seeing much "modern" about it - short stays, short ETT. Be nice if they gave reach, stack and wheelbase dims too.

When you're sat in your normal ridiing position with the cranks at 3 and 9 O'Clock, is the kneecap of the leg at the 3 O'Clock position over the axle of the pedal? That's the first thing to set to get to a roughly accurate riding position. I basically set my saddle position for the most efficient pedalling position (which is middle of kneecap over pedal axle spindle - I'm sure there are others and someone will be along in a moment to disagree).

[[EDIT - pretty much what Jon's saying up there ^ - get your seatpost and saddle position sorted.]]

Once that's set, then consider the bar and stem position. A high rise stem will make your posture straighten, putting more weight on the back of the bike, and making the bike lighter at the front in the corners.

Assuming it is the Jabberwocky, then the geometry is here:  http://shop.vassagocycles.com/JabberWocky-Frame_p_246.html

A size M is up to 6'1", so theoretically an L is correct, at least by Vassago's standards.

I'd suggest trying to get the saddle / pedal position right, and trying a lower rise stem to move your CG further forward. Are you comfortable descending out of the saddle, and are you using a dropper?

The Jabber's a lovely looking bike. It was on my list. FWIW, I'm 5'6" and bought a Stache frame a couple of weeks ago...

That's all great input - thanks a lot to all of you for taking the time to reply.

I currently have 35mm of headset spacers plus an 80mm 10 degree riser stem so I will try moving the saddle forward and removing some spacers.

No dropper at present, and I have no idea about descending yet as my first ride was an almost flat off road loop around Loch Leven.

Yes the Jabber is a great looking bike Mr Udder, I like the skinny tubes and simple lines.  Unfortunately that meant aesthetic concerns overruled those of fit!

In addition I must say how pleased I am with 29x2.6 tyres - so comfortable yet still manoeuvrable.  Fingers crossed the new Solaris will take these on the rear if I decide the Jabber is too small.

Hey Andy, Don't worry about it being a writeoff from the get go - it may just need a bit of tweakage, as the head tube's reasonably long at 120mm. Are you running flat or riser bars and 120mm forks, by the way? If so, then your position will be really upright. Depending on how strong your core is and how flexible you are, dropping the height of the bars will most definitely bring your centre of gravity forward.

By way of illustration, I've got 130mm forks on my Stache, which has a 90mm head tube. I've bunged a 10mm spacer underneath the stem (a very low Ragley Stubbing at 60mm, zero rise) for now and expect to adjust it a little from there. Bear in mind I'm eight inches shorter than you, of course! Stem length and bar width will also change your CofG too: the longer the stem or the wider the bars, the more your weight will move forward in a pedalling position.

My only advice: change one thing at a time. Get the knee / pedal thing sorted, ride it, then try tinkering with the bar height in 10 or 20mm increments. By dropping the stem lower, you're effectively rotating your entire body forward on the bike. If you've ridden another bike for years, any new position will take a bit of getting used to.

Hope this helps and isn't too redundant! Sounds like you have a fantastic environment to try it out. 😀

So .....

I'm a wee bit taller than you. I'm longer in the torso than leg and often end up on the larger of a manufacturers frames.

My Fortitude bikes (I have 2) are within a few MM and half a degree of your ST. I find myself running a layback post and circa 80mm stem. I can run an inline post but find I end up compensating with a longer stem. This can be mitigated a little with a wider bar.

I also run a flat bar with minimal spacers but appreciate that whilst lengthening ETT length may not be comfortable for all.

Id play around with the set up first ... Maybe try a flat bar?

Leggy 6'2" here, so have had the same issue a few times. I alway start with getting seat right height and front to rear position and then adjust bars stem to suit. On some bikes that has meant a 50mm stem on others 90mm. Flat or rider bar also depends on headtube length.

Edit: jabberwocky has an ett of 625mm so quite typical for a large. Think a longer stem would be fine

Large Cotic Solaris would have been fine for you ( I have one )