postpunk

I have a question, I've been riding today on a very steep uphill road with my friend and I noticed that, when I pushed my bike into the 1st gear and tried to gently sit on the saddle (I've been standing all this time as I attempted to finish the climb), my front wheel rose from the ground some 15cm and I almost fell on my back! It kind of freaked me out.
Anyway, my friend said it never happened to him.

I have a pretty large bicycle (GT XL 21.4" frame /75mm stem, I'm 187cm /6' 1 5/8" tall), so could that possibly be the cause? And while I'm here, are there any other technical disadvantages with riding a pretty large MTB?

ed 

This seems to be an interesting display of genius vs. common sense.


It helps to lean forward when you ride up a grade. Often times, your weight will be situated more toward the rear of the bike causing the front end to elevate when pressure is applied to the mechanism that causes the bicycle to propel forward. It's often referred to as a "wheelie".

Other interesting observation...if you are traveling in a forward direction and move the big cross bar with the rubber'y grips on it one way or the other...it helps to displace your weight to the side of the same direction as you move the cross bar.

LesterOfPuppets

Just make sure you kiss your bars next time you sit down. This will keep your front wheel down. Lowering your bars or getting a longer stem can help if it's a constant problem.

Large frame size could have a slight impact if it has a longer head tube, resulting in higher bars (all other things being equal). Sometimes larger frames have slacker seat tube angles which can also put weight farther back compared to smaller frames with steeper STAs.

postpunk

That's the problem, the seat is going backwards as I'm trying to raise its height, so my weight is not balanced in the centre. I think I'll just push the saddle forward a bit more. BTW is it safe to push it forward on a saddle clamp pass that min/max (i forgot wich) point? I know it's probably not but I'll just ask anyway.

ed 

Look at scrublover's bikes. He runs his pretty out there. (search function should find them for ya)

dsprehe89

I have this problem quite often when doing technical uphill trails with roots and rock to climb over. When I lean forward, the rear tire looses traction and spins, and when I lean back the font wheel lifts up. The problem is called "inexperience"; the solution, "RIDE".

samburger

^Sounds like '89 has it figured out (sorry, your username is just too unintuitive to type )

dsprehe89

yeah, that really throws most people off, my name is "Daniel Sprehe" hence the "d-sprehe", and I was born in 1989. And I have had really good luck with sites not having that username taken, which was always an issue in the past, so I've just stuck with it.

postpunk

Very well, thank you gentlemen.('86here

samburger

One year older than I am & you're graduating with a BA in Mechanical Engineering in a year?! Way to make me feel like a failure But kudos to you nonetheless!

dminor 

^^ Don't feel too bad, Sam. At least you're still around: wasn't the mullet born about '89?