Stem length

[Jacoo]

IMO the advancements in MTB geometry (and associated handling improvement) over the past two decades far overshadow the advancements that were made in frame, wheel, fork, brake and drivertrain tech, and these advancements were no doubt significant each in their own right.

 

If all you want in an MTB is essentially a road bike that can ride off-road, i.e. no intention of every riding anything technical, then you can fit a longer stem or do whatever necessary. Just know that you will compromise handling for aerodynamics, comfort or whatever outcome you are trying to achieve.

 

However if you want to use an MTB to ride MTB, then you SHOULD NOT fit a long stem, nor should you get rid of the handlebar spacers and nor should you fit one of those negative angle stems...

Wide bars with short, inverted, dropped stem works perfectly for me. Seat height slightly above handlebars.

[DieselnDust]

In general you have a number of good points here, but some of it could be tweaked a little.

 

Inseam is actually not that important because it doesn't give you a proper biomechanical measurement of leg length. Rather concern yourself with greater trochanter (femur to hip attachment) to the bottom of the ankle length. 

 

 

Bingo, femur length and lower back angle is more important to determine the seats position in space.

 

The measurements of frame sizes are not standardised as you mentioned, and specifically with Mountain bikes where the seat tube runs at all sorts of angles to shorten the wheel base while accommodating 29" wheels. For instance our ErgoFit system uses 2 varying angles to compare Fram size (either a 73 or 90 degree angle). In general your saddle setback should be ~10% of saddle height (when measuring with a 73 degree angle).

 

10% of saddle height measured from where? pedal or bb axle centre?

 

In general you want your saddle setback to be very similar on the road bike or MTB, but having them exactly would not relate to the exact same pedal stroke as we generally see slightly shorter cranks as a standard on road bikes compared to MTB's.

 

Yip , i'l subscribe to that. makes fitting across bikes easier and standard

 

Wider bars may also reduce your reach due to the sweep on the bar. Your shoulder angle is also more important than stem length. The notion that a shorter stem is better for handling is also not always true

 

Wider bars can also increase your reach when the bar is too wide It really depends on shoulder width and neck shoulder flexibility, arm length and torso length and flexibility.

 

Hence I always prefer to start with getting the saddle in the right space, then adjust the stem length and bar width according to the riders flexibility. There are no hard and fast rules here. Physical  variances between people can be great within the same height

[Jarred]

 

In general you have a number of good points here, but some of it could be tweaked a little.

 

Inseam is actually not that important because it doesn't give you a proper biomechanical measurement of leg length. Rather concern yourself with greater trochanter (femur to hip attachment) to the bottom of the ankle length. 

 

 

Bingo, femur length and lower back angle is more important to determine the seats position in space.

 

The measurements of frame sizes are not standardised as you mentioned, and specifically with Mountain bikes where the seat tube runs at all sorts of angles to shorten the wheel base while accommodating 29" wheels. For instance our ErgoFit system uses 2 varying angles to compare Fram size (either a 73 or 90 degree angle). In general your saddle setback should be ~10% of saddle height (when measuring with a 73 degree angle).

 

10% of saddle height measured from where? pedal or bb axle centre?

From centre of the BB 

 

In general you want your saddle setback to be very similar on the road bike or MTB, but having them exactly would not relate to the exact same pedal stroke as we generally see slightly shorter cranks as a standard on road bikes compared to MTB's.

 

Yip , i'l subscribe to that. makes fitting across bikes easier and standard

 

Wider bars may also reduce your reach due to the sweep on the bar. Your shoulder angle is also more important than stem length. The notion that a shorter stem is better for handling is also not always true

 

Wider bars can also increase your reach when the bar is too wide It really depends on shoulder width and neck shoulder flexibility, arm length and torso length and flexibility.

 

Hence I always prefer to start with getting the saddle in the right space, then adjust the stem length and bar width according to the riders flexibility. There are no hard and fast rules here. Physical  variances between people can be great within the same height