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Discussion Starter · #1 ·
My 2011 jamis dakar xcr team is not as twitchy as I would like and has a tendency to push the front tire in turns. I'm not a geometry guru but I'm guessing the trail in the frame and fork setup is meant more for stability at speed.

Is there anything I can do to help this? Since I've only got a 100mm fork I'm hesitant to increase the sag on the front.

Is there anyway to change the rear ride height other than the shock sag?

Taller tire in the back or shorter in the front?

Different fork?

Other thoughts?

thanks!
 

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In general a good way to increase the steer speed of a bike would be to put a shorter stem on the bike. then to add room to the cockpit and add stability a wider bar helps. Doing this will put your weight further back on the bike. Corning is one of the more challenging things to do on a mountain bike. It takes some skill and technique once you master a few techniques you will learn to load the front wheel a little more keeping the front tire tracking better along with leaning the bike over turning your hips into the turn, looking through the turn, and weighting your outside foot.

Tires could play a factor if you don't have something that does not have a lot of bite on the shoulder of the tire you want want to try something with more bite. Also tire pressure also plays a role in this to much the tire cannot conform to the terrien you're riding on.


to change your Geo up front you could make it steer a little snappier with an increased head angle, so if you currently have a 70* angle now you could increase it to a 71* giving it a snappier feel. decreasing it would do the opposite make it a little slower steering but more stable at speed. this could be accomplished with an angle set if your bike would accept it.

i would start with a stem and some riding technique


here are some helpful videos


How To: Cornering and Straight Line - Pinkbike

Line Choice Video - Pinkbike

Braking Video - Pinkbike
 

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Discussion Starter · #3 ·
Thanks for the response. How do you change the head angle? This is probably a dumb question .. Obviously I'm new to working on mt bikes.

I don't think I'm having a technique problem. I've been riding for 20 plus years and also have tons of experience on dirt bikes and race street bikes. I just have never had a nice full suspension bike so getting it setup is my biggest challenge.
 

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Short stems are good for steep DHs to keep you from going over the bars, but a longer stem can put more weight on the front wheel giving you more traction. What size bar and stem are you riding and the bike is a good fit?


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My 2011 jamis dakar xcr team is not as twitchy as I would like and has a tendency to push the front tire in turns.

[...]

Other thoughts?
Run your front tire about 5psi lower than your rear tire. That will give you a little more grip on the front, or a little less grip on the rear, depending on how you look at it.

If you have a 1.5" head tube, you can use a Cane Creek Angleset with a 1 1/8" fork, and set it up for about 1 degree steeper than the frame's default head tube angle. I've done this on one bike just to see what difference it would make, and while it does make a difference I think it's pretty subtle.

That said, I strongly suggest adjusting your tire pressures. It costs nothing and it's trivial to undo it if you don't like the results. I run about 30 front and 35 rear.
 

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Run your front tire about 5psi lower than your rear tire. That will give you a little more grip on the front, or a little less grip on the rear, depending on how you look at it.

If you have a 1.5" head tube, you can use a Cane Creek Angleset with a 1 1/8" fork, and set it up for about 1 degree slacker than the frame's default head tube angle. I've done this on one bike just to see what difference it would make, and while it does make a difference I think it's pretty subtle.

You could also run a fork with a longer axle-to-crown length - which basically just means a fork with longer travel, too - and that will increase the head tube angle. I think you get roughly 1 degree lower HTA per 20mm but I haven't looked into this for a long time so you should double-check that figure. Or someone else will chime in to set me straight.

Running a longer fork will also raise your crank (by a bit less than half the amount of the length increase) and tilt your seat tube back (by an amount equal to the HTA decrease) and thus move your seat rearward a little bit (this trigonometry problem is left as an exercise for the reader).

It wouldn't hurt to estimate how much those will change, and see how the resulting geometry compares to other bikes on the market. I think you'll find that it's all no big deal, but then again I've always been of the opinion that how you ride matters far more than what you ride (with bikes, with skateboards, with snowboards, etc) and with bikes there are a lot of other variables you can adjust to fine-tune the feel (stem length, stem height ,bar width, seat position, yadda yadda yadda).

All of that said, I strongly suggest adjusting your tire pressures. It costs nothing and it's trivial to undo it if you don't like the results. I run about 30 front and 35 rear.
He wants a faster steering bike, steeper HA.


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Discussion Starter · #9 ·
The cane creek product looks interesting. I might give this a try. The adjustable version goes either direction up to 1.5 degrees.

I will try lowering front pressure a bit to see if that helps with pushing.

Does anyone make aftermarket rear shock linkages? Seems like a simple matter to raise the rear ride height with a slightly longer linkage or an eccentric pivot.
 

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Discussion Starter · #10 ·
Unfortunately Cane Creek told me their product will not work with my frame.

From Cane Creek:
Unfortunately that frame is not AngleSet compatible. The AngleSet requires press in cups, that bike has an Integrated (IS) headset, so the bearings just drop right into the frame with no press in cups.
 

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Discussion Starter · #11 ·
Short stems are good for steep DHs to keep you from going over the bars, but a longer stem can put more weight on the front wheel giving you more traction. What size bar and stem are you riding and the bike is a good fit?


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The stem feels about right to me. I've experimented with holding my weight more forward while doing flowing single track turns at speed and the bike does feel way better. The problem is I feel exposed riding that far forward and will probably eventually go otb. I would much rather figure out how to dial in the bike so I can ride back where it feels normal.
 

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Discussion Starter · #13 ·
As already mentioned try a Works headset : Works Components - Angle Headsets to fit Most Frame Types & CNC Bicycle Components Proudly Made in the UK . If you are really happy w/ your current cockpit & suspension settings why throw band-aids into the mix. If you want to change the steering alone run the Works headset. i have used a few and they were install & forget.
Will they work with an integrated headset? I've got an email out to Works but have not heard back yet.
 

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I think you are fighting this battle the wrong way.
The HA is 71.5, which is pretty friggin steep for a 26er. You most likely have setup issues, or a bike that is too big for you.
If it feels better when you move your weight forward, then you should be looking at getting a longer stem to naturally push your weight forward, or a smaller frame size. Even a 10mm longer stem could make a difference. If it feels like you are going to go OTB, that is usually due to a steep HA, and/or not being able to get your weight back/down. Maybe a dropper post could help in proper weight distribution.
I had the same issue on a Mojo HD years ago. Tried all sorts of stuff, then eventually stepped down a frame size and it's been pure handling bliss since then.

Raising the rear with a longer shock *could* work, provided the bike's linkage allowed for the change. However that will increase your bottom bracket height, which will result in worse handling, and you'll still be left with your weight too far back, allowing the front end to keep pushing in turns.

Answer these so we can have more info to work with.
How tall are you?
What is your bike size?
What length stem?
What width handlebars?
 

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rzip
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My bike was washing out the front end and I turned the stem up side down ( lowered the handlebar) and that fixed it. To quicken the steering on any bike ,just shorten the handlebars. You can experiment by simply moving your grips and controls inward, if you like it you can then cut a bit off your bars. A shorter stem also quickens the steering.
 

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He wants a faster steering bike, steeper HA.
Whoops, you're right - I'll remove the part about the longer fork.

A shorter fork and lower BB sounds like too high a price to pay, especially considering that his current fork doesn't have much travel to begin with.
 

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"El Whatever"
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It could be suspension set up too... I can't remember but too much or too little rebound can cause the front to oversteer/understeer
 

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Discussion Starter · #20 ·
Thanks for all the ideas!

Here is a link to my bike build.

Jamis Dakar XCR Team Bike 2011 > Complete Bikes > Mountain Bikes | Jenson USA Online Bike Shop

I have the 19" frame so looks like the head angle is 71.8. I bought used so assuming the bars and tube are stock but I have not measured.

I'm 170lbs geared up, 5'-11".

I only feel like I'm going to go otb if I purposefully ride with my weight way forward in an effort to feel how the bike would turn with different geometry.

The stem height "feels" just on the verge of being to far forward/low which would I think be uncomfortable for long rides if I increased it. I did move the seat forward.. Maybe ill try a bit more ad see if I think I can tolerate a lower bar.

My shock blew its seals (including the damper!) on my last ride so now I'm at the point where I have to do something. I think my rp23 is the 6.5x1.5 setup. Please correct me here.. So 6.5-1.5=5" min length, the next size up that might work is 7.5x2, min length is 5.5. So that's a 1/2" . If I have a 100mm range at the wheel with a 1.5" shock travel, my ratio is 4/1.5=2.66, so 1/2" will reduce the amount the back can compress by 1.33". That sounds like a lot to me. I think I just answered my own question there.

I guess I'll just get my shock rebuilt and try to run less sag in the back and more in the front and play with the bars if that doesn't work.

i think the main problem is if I knew now what I knew 6 weeks ago I would have bought a different bike.
 
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