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Discussion Starter · #1 ·
I bought an 04 Epic end of fall last year and did a few add-ons over the winter...

I noticed when I bought the bike the bar reach was a little long for me, but in general the bike fit good. I was unable to try a medium, but I was assured that for my body I would be using to much seatpost, Medium endoro and stumpy where to small for my liking. I'm currently using about 7in on a large and I'm around 5'10''..

My question if I change the stem from 120mm to around 90mm what will the effect be on the handeling? Will it make it more twitchey on decents and uphills? WIll it make it turn like an 18 wheeler? I

I haven't decided on 90mm I will have to try some different sizes and the bike shop. As for bar height I believe I'm right where I want to be..

Thanks for any input...
 

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New2Mountain6 said:
I My question if I change the stem from 120mm to around 90mm what will the effect be on the handeling? Will it make it more twitchey on decents and uphills? WIll it make it turn like an 18 wheeler?
I'm of the opinion that it would make your bike handle better. However i must first make the disclaimer that i hate long stems, they make a bikes handling feel terrible to me. The steering feels completely vague and unresponsive with stems of that length, and going downhills sucks because of the extra forward bias. That length is only good for an XC racer or someone who enjoys climbing more than descending.
These words are purely based on my own experience so don't take them as gospel, but honestly, i really can't see it being any worse using the 90mm stem. I would hope that in fact it makes your bike feel better to ride.
 

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New2Mountain6 said:
I bought an 04 Epic end of fall last year and did a few add-ons over the winter...

I noticed when I bought the bike the bar reach was a little long for me, but in general the bike fit good. I was unable to try a medium, but I was assured that for my body I would be using to much seatpost, Medium endoro and stumpy where to small for my liking. I'm currently using about 7in on a large and I'm around 5'10''..

My question if I change the stem from 120mm to around 90mm what will the effect be on the handeling? Will it make it more twitchey on decents and uphills? WIll it make it turn like an 18 wheeler? I

I haven't decided on 90mm I will have to try some different sizes and the bike shop. As for bar height I believe I'm right where I want to be..

Thanks for any input...
The longer stem works for me but I feel scrunched up with a shorter stem. Besides that point, someone posted this spreadsheet before that may be helpful in figuring out how the shorter stem will change your hand position and stance on the bike. You will have to fill in the fields.
http://www.boomspeed.com/iviguy/stem_and_handlebar_comparator.xls
 

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stem dynamics

a shorter stem decreasese the leverage that you have on the front wheel allowing smaller precise movements to affect the turning to a greater degree. A longer stem allows you to make larger movements to get the same affect. This just means that the shorter stem allows you to be more precise with less movement. This also means that it is less forgiving of hamfisted maneuvers.

A shorter stem will move your weight back hindering climbing to some extent, or in other words making the front wheel lighter and giving it the tendency to lift on climbs. Opposed to this it will also give you the ability to be further behind the front wheel allowing you to descend with more confidence and get behind the bike on the steeps. The increase in steering precision comes into play here allowing you to delicately pick lines on the uphill and downhills without as much upper body movement and the corresponding weight shift associated with them.


This can all lead to better skill in the steeps down but a little trade off in the uphills.

Finally depending on your bike position this could center your center of gravity and give you better cornering performance. Or it could bias you to the rear causing you to (understeer) push in the corners and causing you to re-adjust your position in the corners.

For me I have gone from a 110 to a 50 over the last few years, somewhat comprimising my climbing skill (which I since have adjusted my technique to compensate) for a greater increase in descending prowess. I find that I have also adjusted my cornering technique to steer with my hips much more as well, keeping me more centered on my bike and reducing push.

My suggestion, beg, borrow, or order a cheapo stem in the length you want to try and try it. Don't go out and buy a $$$ stem in the length you think you might like. Try a bunch of lengths where possible, Supergo is always clearing out cheapo stems in many lengths.

good luck
 

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rockcrusher said:
stem dynamics
Excellent write-up, crusher. I always cringe when people reply to questions like this with, "you have to go with XYZ," but never give any explanation. I generally like to give an explanation of the pros and cons, and maybe even offer my opinion, but try to let the reader make up their own mind. I'm an engineer, so I like to try to explain the inner workings and physics behind things like this.

Good job and excellent advice!

FRC
 

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Measuring

RobG said:
I was thinking a shorter stem, but there is no number on my current. How do I measure it to find its current length and rise?

Thanks
generally you can measure the length of your stem from the center of the top cap bolt to the center of the handlebar parallel along the length of the stem. This will give a general length of the stem. Usually they are sized in 5mm increments so you can expext to hit around, oh say, 110mm.

Rise is a little more complicated. Americans use the + or - degrees from perpendicular, that is, they add or subtract the rise from an imaginary line perpendicular to the steer tube. Ofr example, +5 degree stem would rise 5degrees above the imaginary perpendicular line. -5 degrees would be the same stem flipped over and sinking 5 degrees below the imaginary perpendicular line. Generally used in the mountain arena.

europeans measure the stem as a positive measure from the steerer tube so a -5 degree stem is really an 85 degree stem and a positive 5 degree stem is a 95 degree stem. Generally this is used exclusively in the road arena

Measuring rise is simple to estimate. Just measure perdendicular from the lowest part of your stem on the steerer tube to its intersection with the lowest part of the handle bar. This is a perpendicular measure (the perp. length) remember not the actual length. Now from this point measure up to the handlebar at its lowest point as well. This is the height

Put the two numbers in to this equation: rise=inverseTAN(height/perp. length)

that is your rise. Generally between 5-15degree on most performance modern mountain bikes and between 10-35 degree on most comfort bikes, and possibly between 0 and -10 degrees on XC race bikes and road bikes.

Another thing to note when changing stems is that the length may change but unless the rise is increasing it will actually go downin height, so for a more drastic change, say 120 to an 80mm stem that both have a 5degree rise, you will notice that the bar will seem lower and closer. You can counter this by running a few extra spacers or you can buy a stem that is a little higher rise, say from a 5 degree to a 7 degree (or even a 10degree) or you can run a riser bar with a higher rise etc.
 

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Discussion Starter · #11 ·
Great help rock crusher. I believe my LBS sells specialized stems and they may take and trade me for a shorter legnth since mine looks like brand new. At least I'm hoping..

I don't believe going shorter will make the front end to light considering I have a hard time doing a wheelie with my current set-up..

Thanks for all the help and replies...
 

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I wouldn't worry about stem length ruining your handling. I had a frame that was a tad too big, so I put the shortest stem I could find on it, couldn't have been longer than 50mm or so. I really didn't notice much of a diiference in how the bike handled, huge difference in comfort. Go for what feels comfortable, you'll adjust to the handling.
 

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Try a 110 or 105 first..

New2Mountain6 said:
I bought an 04 Epic end of fall last year and did a few add-ons over the winter...

I noticed when I bought the bike the bar reach was a little long for me, but in general the bike fit good. I was unable to try a medium, but I was assured that for my body I would be using to much seatpost, Medium endoro and stumpy where to small for my liking. I'm currently using about 7in on a large and I'm around 5'10''..

My question if I change the stem from 120mm to around 90mm what will the effect be on the handeling? Will it make it more twitchey on decents and uphills? WIll it make it turn like an 18 wheeler? I

I haven't decided on 90mm I will have to try some different sizes and the bike shop. As for bar height I believe I'm right where I want to be..

Thanks for any input...
the jump your suggesting will be a big change and maybe one you dont like. If you do however make the gap choose a 90 with no rise.
 
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