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PostPosted: Wed Nov 14, 2012 6:44 pm 
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I just switched bikes going from a RM vertex 26in to a RM vertex 29er. There is a slight geometry change and my position is a bit more upright and shorter on the 29er, partly because im now using a non setback seatpost.

im using the same stem (100mm) on my 29er that I was using on my 26in bike. I riding the same type of bar: 10deg sweep flat bar but I run it 20mm wider then before. I feel comfortable on those 680mm bars

I find my position a bit too upright and I would like to make the bike handle faster and more nervous. I know it wont be the same as my 26in bike but I'd like a faster slightly faster handling.

Would using a neg -17deg 100mm stem make any difference in steering speed? Should I go with a shorter stem? Shorter bars? Shorter stem would put me more upright and I think im already a bit too much...

thanks for comments

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PostPosted: Thu Nov 15, 2012 3:01 am 
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The sure-fire way to make the "steering speed" faster would be to drop the fork travel to 90 or 80mm (assuming you are at 100mm already).

Shortening the stem will possibly make the steering feel faster, but be aware the shorter you go the more upright you get. The more weight you have over the front wheel the more responsive the bike should feel, so rather than going a shorter stem, try going lower first. You should really choose the stem length to get the right fit on the bike, then adjust height to get your handling/steering right I think.

I run a -30deg stem on my 29er (I am 172cm) which gives me only around 2cm of bar drop from my saddle with the fork still at 100mm.

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PostPosted: Thu Nov 15, 2012 4:08 am 
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Thanks

Im at 100mm travel. I will try a -17d 100mm stem and see what happens. Not sure about reducing the travel as we have some very bumpy stuff arround here, plus, my lbs isnt "qualified" to reduce my rockshox travel...

A -17 stem should bring things down nicely to begin with


Any other comments appreciated

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PostPosted: Thu Nov 15, 2012 5:43 am 
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FWIW I can wheelie fine with 3 spacers and riser bars on my 26", couldn't wheelie at all on my 29er until I put a -17 90mm stem on, as apposed to -6 previously.

Obviously the ability to wheelie is a pretty minor factor in riding smooth (where smooth=faster), but the steeper and shorter stem does help overall nimbleness....... until you go downhill, you have to have your bum behind the rear-mech or you crash :wink:

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PostPosted: Thu Nov 15, 2012 1:52 pm 
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anyone knows if a 100mm 0d stem VS a -17d 100mm stem will have a difference on handling?

Not sure on the length, if I drop to 90mm it'll be a bit short and I cant get my saddle back anymore...

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PostPosted: Thu Nov 15, 2012 4:09 pm 
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The downslope stem will put more weight on the front wheel, changing the stem length doesn't make it handle faster, it just makes the arm movements required to get it to turn smaller which are not actually the same thing (though frequantly confused). A 29er will always feel slower to turn than a 26er, fact of life, longer wheelbase and more inertia/precession.

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PostPosted: Thu Nov 15, 2012 4:31 pm 
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TheRookie wrote:
A 29er will always feel slower to turn than a 26er, fact of life, longer wheelbase and more inertia/precession.

+1

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PostPosted: Thu Nov 15, 2012 4:37 pm 
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Like i said, i am aware of all those 29er is slower etc etc

What I want to know is some cockpit tuning tips to male it handle a bit faster. More weight on front wheel=faster?

The vertex 29er as a rather short WB for a 29er.

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PostPosted: Thu Nov 15, 2012 5:08 pm 
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More weight on the front wheel = more grip, nothing in the cockpit will make it handle faster (in the true sense of the phrase), narrower bars or shorter stem will make it FEEL like it handles faster.

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PostPosted: Thu Nov 15, 2012 5:30 pm 
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Thanks

think im gonna go with a negative 17d stem with same length. I feel reducing the stem length would have me way to upright. I could move my saddle back 5mm also.

I hear what you mean with hanbling faster and feeling faster. I might also reduce the bar width to 660mm like my older bars. I guess its a matter of time, I only been riding the 29er for 10-12 rides now.

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PostPosted: Thu Nov 15, 2012 9:08 pm 
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Don't forget lower bars will stretch you out slightly more, so with a -17stem you could shorten it slightly for the same stretch.

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PostPosted: Thu Nov 15, 2012 9:23 pm 
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good point

actually I think it'll be good if im a bit more stretched. Maybe it will be closer to my 26in bike position.

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PostPosted: Fri Nov 16, 2012 11:22 am 
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Lowering the bars with a more neg stem will weight the front wheel more which can give you more grip on corner entry and through the apex but it won't make the bike steer any faster. If your front end is not "turning in" quickly enough on corner entry they dropping the bar height is a worthwhile experiment. If the bike is pushing wide on corner exit or not settling through the apex then you may need more rebound damping.

You can also try running more sag (lower air pressure) on the fork or less low speed compression which will have the fork run lower in its stroke on corner entry. This will steepen up the head angle and give you faster steering.

If you're just after faster steering like a 26er then you are probably not going to get that on a 29er no matter what mods you make.


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PostPosted: Fri Nov 16, 2012 1:48 pm 
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yeah the fork could use some tuning. Its a rockshox SID and its so much more sketchier then my fox. I will lower the psi and see what happens.

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PostPosted: Fri Nov 16, 2012 3:56 pm 
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Along with Rider10's suggestions, you can try 5 psi more in the rear shock. And/or adjust the rear shock rebound. If the rebound is set too high, the rear end will ride lower, regardless of static sag measurements.
That said, I'd been fighting with a front end push on my epic29er for a while, trying all sots of suspension workarounds. In the end, a -17 stem made it all better.


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