A bike has the wheelbase it needs for the style it is. Changing out the whole bike for a similar one with a slightly different wheelbase would be... nuts.
An average current MTB has about a 125 cm wheelbase.
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Genesis 49:16-17
"Well, well!" said Holmes, impatiently. "A good cyclist does not need a high road. The moor is intersected with paths and the moon is at the full."