[have2ride2day]

I've been playing with bar width and stem length for a while now and was wondering what effect lowering my stem, by moving headset spacers, would have on the way the bike handles. If I lower my bars will it move my weight forward and improve climbing? Will it make me feel too forward on descents? I've read through many threads on bar width and stem length, but can't find much on stack height. Seems like everyone is after a lower stack height these days, but noone really says why.

I'm riding a Tracer VP with a 50mm stem, Dirty 30 bars, CK Devolution headset, and 25mm of spacers. I would like the bike to climb better when things get really really steep.

 

[blcman]

Your on the right track with the info you've gathered already....
so if you think about it you will have to use riding technique to get everything from any one setup...
bend your elbows and moving foward for climbing will work and lowering your seat and moving rearward for decending.
The stack height and bars should be a comfort thing for all the in between stuff! :thumbsup:

 

[b-kul]

im not sure what effect stack height has either. just guessing here but it would seem lower is better for dh cuz all the racers have their stems slammed but maybe that is just to combat the longer forks?

 

[bquinn]

On my Enduro with 90mm stem, I swapped the spacers from bottom to top, about 12mm, and it changed the way my bike handled. It's hard to imagine that little difference made a big difference but it did. All I can say is play around with it and see how it effects you and your bike.

 

[have2ride2day]

On my Enduro with 90mm stem, I swapped the spacers from bottom to top, about 12mm, and it changed the way my bike handled. It's hard to imagine that little difference made a big difference but it did. All I can say is play around with it and see how it effects you and your bike.

How did you feel it changed the handling?

 

[lew242]

Plus one don't really understand the difference here too.

I've got 27mm of spacers. I'm sure lots of DH racers have their stem and bar slammed because they have 180mm-200mm travel and a direct mount stem.

 

[bigbeck]

Lowering the stem gets more weight on the front. Great if you enjoy doing endos. I keep my bars as high as possible because I do a lot of technical downhill runs. Of course when I do steep climbs,my butt is on the very tip of the saddle and I'm wishing the bar was lower.

Always a compromise. If you get your bars too low, you can get a sore back or neck on long rides in addition to the fun filled downhill endos. LOL It's just another one of the many things you need to experiment with on a bike.

 

[blcman]

Hey h22, what size stem and bars came on the bike originally? Did a LBS fit the bike to you etc..?
That stem setup is really more of a fr setup and puts your weight more rearward..hence worse for climbing
with out concerted effort leaning and scooting forward! Lowering your stem downward (redundant I know haha) will help for climbs.
But how will it feel for all the other riding in between. That'll be up to you to decide if it works.

 

[blcman]

Lowering the stem gets more weight on the front. Great if you enjoy doing endos. I keep my bars as high as possible because I do a lot of technical downhill runs. Of course when I do steep climbs,my butt is on the very tip of the saddle and I'm wishing the bar was lower.

Always a compromise. If you get your bars too low, you can get a sore back or neck on long rides in addition to the fun filled downhill endos. LOL It's just another one of the many things you need to experiment with on a bike.

Dang! I could've saved some typing had I seen your post BB. Good answer!:thumbsup:

 

[Kaizer]

IMHO, it's a good idea to have some access steerer tube left on top when changing to a new fork.

Been experimenting with stem height since started riding (which is not long ago). Still looking for the right height and reach... LOL

Lately been trying out lowering the stack height and notice the bike's handling comes alive. Maybe it's too high on the previous setup (30mm from a zerostack headset). Lower it down by 20mm now. Needs more 'test rides' to confirm it. And to add in more confusion myself, contemplating on changing to a wider and lower bar as well.

Although it seems like WC DHlers are going for lower and lower stack height with those low risers and such. I saw a pix of Steve Peat's V10 running quite a handful of spacers to bring up the stack height to his liking.

 

[blcman]

.. I saw a pix of Steve Peat's V10 running quite a handful of spacers to bring up the stack height to his liking.

Could be that Peat's a pretty tall guy for a DH'er... 6'2"ish compared to like a Sam Hill 5'4"!

 

[Kaizer]

Could be that Peat's a pretty tall guy for a DH'er... 6'2"ish compared to like a Sam Hill 5'4"!

Well, this shows that it's a personal preference then...

The reason I'm bringing up Peaty's cockpit setup is that, sometimes it's more of a hype rather than a necessity. Since he's running a stack of spacers to bring up the low riser, what's the problem with using a high riser and leave the spacer at home/pit?

 

[blcman]

I'm with you there kaizer on the preference thing!

Totally hijacking this thread now, but I wonder why not many DH'er use risers?

Maybe the amount of torque they get at the bars the flatters bars would be less likely to rotate on them!

Just a thought!:thumbsup:

 

[fotu]

they used to. Risers are out of fashion. I think they look cooler though, specially with 25.4 clamp diameter.

 

[bmxconvert]

I'm a big fan of semi-wide low front ends as seen in the bikes that I ride the most out of my own collection:
Niner EMD: 710mm flatbar, slammed stem/crown(135mm minimum stackheight on fork)
Giant Reign: 720mm wide 19mm rise bar, zero stack headset,slammed 80mm stem
GT DHI: 745mm wide flatbar, Directset(least stack height of any standard 1 1/8" headset) slammed boxxer crown/zero rise stem
IronHorse Sunday: 745mm 19mm rise bar, zero stack headset, slammed boxxer crown/zero rise stem
Foes Prolite: 710mm wide 19mm rise bars, slammed zero rise 80mm stem
Giant STP: 745mm wide 19mm rise bar, zerostack tapered headset, zero degree rise stem, 10mm spacer.

I find that lower front ends allow you to really push into corners better than a tall front end. I don't find any adverse effects of a low front end for downhills, even technical stuff.
However, on my jump bikes such as all of my BMX bikes and both my dirtjumpers I run a touch taller front end, not much. I just find that I get rather "corkscrewed" on my 360's and the like with real low front ends. It also tends to make quick tech lip style tricks really awkward with a low front end.

 

[half_man_half_scab]

I am so happy this question has been asked. My DH friends all have their stems flush with the headset, and I thought they were in some form of secret masochistic cult. On my XC bike I would max out spacers under the stem to keep from endoing. Perhaps the bike was too small for the job, but its left me with a reluctance to remove any spacers on my current rig... which has a float 180. I've started experimenting by removing a centimeter of spacers, and I guess I'll stop when I start endoing.

Am I correct in my assumption that dropping the stem will feel twitchier, in contrast to raising it making it floppier? Or is that just an axel to crown thing? If it's true, is this the reason why DH riders drop their stems? I can't imagine they are trying to improve climbing performance!

 

[Kaizer]

IMHO, any height alterations north of the HT does not changes the frame geometry. Anything south of the HT does.

A steeper HTA will be twitchier/sharper handling. A slacker HTA will be more stable/slow handling.

By altering the amount of spacers below the stem, the HTA remains constant. What it changes is the rider's weight distribution over the bike.

Example on a flat land. a high stack will position the rider more upright, therefore more weight onto the saddle (if seated) or pedals (when standing). Hence more rearward weight bias. For a low stack, it's the opposite.

How does the weight distribution affect one's riding, depending very much on their style of riding or what they're used to.

My take on the stack height would be to look at what the WC pro's body position. There's always a reason for it and who am I to argue with the pros?

On a personal note, after I lower my stack height by 20mm, the front end tracks better, both on accent and descents. It gave me more confidence too during cornering.

Looking at the 'Attack Position' by Mr Lee McCormack:

*Pix too big...
https://4.bp.blogspot.com/_cXc0R2OZKfA/TKM-wxcfPLI/AAAAAAAAEMc/qMSc8F-RqKE/s1600/KI+002.jpg

When the back is flat, the arms are bent. The amount of bend determines the amount of both neg and pos travel the human suspension has. Now when it comes to the preferred amount of human suspension, is very subjective and personal.

 

[dropadrop]

Could be that Peat's a pretty tall guy for a DH'er... 6'2"ish compared to like a Sam Hill 5'4"!

Could also be that his bike set up changes from one track to another...

 

[Kaizer]

Could also be that his bike set up changes from one track to another...

That would be a very interesting idea indeed. Wondering under what circumstance does changing stack height to suit the terrain?

 

[dropadrop]

I would imagine when you are riding something stupidly steep you might prefer to have the handle bars higher to make it easier to get your weight back. Personally I currently have my stem flush against my headset, and I did previously have about 25mm of spacers underneath.

The lower handlebar (as mentioned) makes it easier to put weight on your front wheel, and personally (I'm also pretty tall with a frame to the smaller side) I feel I can still get my weight easily enough. I did not notice a huge difference, but I do have less of a tendency to wash out. I'm sure the forks length and head angle affects this a lot, I have about 66.5 HA so I don't really feel I'm going to go OTB either way...