Mountain Bike Reviews Forum banner
1 - 15 of 15 Posts

·
Registered
Joined
·
446 Posts
Discussion Starter · #1 ·
I have a SC Chameleon and have a 90mm stem and the seat set way back. Pretty much as far back as you can go. Wondering if a Thomson lay back seat post that sets it back 5/8 of inch (according to website) would be a good way to go. Would this be a better way to go instead of a longer stem?

Besides, Greenfish has 15& off this weekend...
 

·
Registered
Joined
·
549 Posts
Longer stem-length will result in a "twitchier" feeling bike because your weight will shift forward (over the front wheel). You may be able to compensate a little for the quicker steering by installing a wider handlebar. . . this just being a bigger radius created by the bar - takes a little longer to steer.

If you opt for a setback-post, the "Elite" is probably the better choice (over the "Masterpiece") on the Chameleon - this is assuming you're using the Chameleon in it's intended realm of dirt-jumping and "urban assault". The "Masterpiece" is solid but it is Thomson's lightweight version - I doubt either ("Elite" or "Masterpiece") would break but considering what you're doing and where the seatpost is if it should snap. . .
 

·
Registered
Joined
·
29 Posts
It's hard to answer your question without more info. What kind of riding do you do? What size is the frame? What size are you? What travel fork are you running? How does the bike handle now? Also, why do you feel the need for a layback post/longer stem? It sounds to me like you are trying to make the best out of a frame that may be too small.

My experience may help. My main bike is down with pivot issues, so I pulled out my backup bike - a large Chameleon with 100mm stem, 4" travel Fox Float, and straight up Thompson post. The bike has basically been unused since I built it up, so it wasn't really dialed in. My first ride on the local tight twisty trails I felt like I couldn't get the front wheel to carve; the head angle felt too slack, and I couldn't dive into the corners like i wanted. I adjusted my seat forward, to get more weight over the front tire, which gave me more traction as well as more sag and a steeper effective head angle. Another welcome benefit of moving my seat forward was that my a$$ was no longer getting hammered as hard by the ultra stiff Chameleon rear triangle.

My point in all this is not that my situation is exactly the same as yours, but that when you start making drastic changes to your riding position, you are going to run into some interrelated handling issues. I personally think that a layback post is a band-aid that will have a negative effect on handling for xc or all mountain use, especially on a bike with a tight rear triangle like the Chameleon. If you need to stretch out I'd run your seat as far back as you can get it on the post you have and go for a 100mm stem.
 

·
Registered
Joined
·
446 Posts
Discussion Starter · #6 ·
Thanks for all the responses.

I mostly ride trail / all mountain. I live in Norcal (Auburn) and do a fair amount of climbing, but that is only to go down. My Chameleon is set up as a trail bike as I ride with fast xc guys, but also do rocky, technical descents, and hit 2-3 foot jumps. I have a small frame and am 5'4, but I think my upper body is more towards a medium. So I think I am trying to make it fit a little bit better. It does fine, but could use a little bit more room.
 

·
Registered
Joined
·
17 Posts
assuming you're set up is xc....
1. set saddle height (how high? google it!)
2. get plumb line then adjust saddle fore and aft position. how? here: http://www.caree.org/bike101bikefit.htm
if plumb line is in front of the pedal spindle even when saddle is set all the way back then consider getting a thomson setback or maybe (let's hope not) your fame might be small for you. power to every pedal stroke is what you're trying to achieve here.
3. when all is good with #2 then feel if you need a longer stem. this one is for riding position and bike handling. it all depends on you now. if you want to be more aerodynamic get a longer stem but then riding comfort will suffer. so again this one's up to you really but if you feel cramped on your bike even with a 110mm stem installed ,then i think you have to consider getting a new frame.
just read more about bike fit in the link i gave you. there are a lot of things to consider when it comes to fine tuning your bike to your body. goodluck. peace!
 

·
Registered
Joined
·
29 Posts
Well, if technical, rocky descents are a big part of your riding, then the layback post may be the way to go. A 90mm stem already seems pretty long for a small frame/someone your size, although I don't know from experience as I am 6' and ride a large frame. Maybe some small frame riders could chime in here with what kind of riding they do and what size stem they run.
 

·
Don't touch me!
Joined
·
873 Posts
emptybe_er said:
Longer stem-length will result in a "twitchier" feeling bike because your weight will shift forward (over the front wheel). You may be able to compensate a little for the quicker steering by installing a wider handlebar. . . this just being a bigger radius created by the bar - takes a little longer to steer.

If you opt for a setback-post, the "Elite" is probably the better choice (over the "Masterpiece") on the Chameleon - this is assuming you're using the Chameleon in it's intended realm of dirt-jumping and "urban assault". The "Masterpiece" is solid but it is Thomson's lightweight version - I doubt either ("Elite" or "Masterpiece") would break but considering what you're doing and where the seatpost is if it should snap. . .
Assuming the same force is applied, a longer stem will 'understeer' compared to a shorter stem. i.e. longer = more stable, shorter = twitchier.
 

·
Derailleurless
Joined
·
9,122 Posts
mr. umali said:
if plumb line is in front of the pedal spindle ... maybe your fame might be small...
Actually, not so.

Like most production frames, the Chameleon's 72° seat tube angle is the same across the various sizes.

Wouldn't matter if he was on a small or a XL, his saddle would end up with the same range of adjustment relative to the crank. Only difference would be the amount of exposed seatpost.

Rico, a Thompson layback is a good post, but doesn't do anything different compared to other setback posts like Salsa's Shaft, or Race Face's Diabolus. In fact, with only 16mm of setback, plus the wide rail clamp (which is good for strength), you've got a pretty limited range of adjustment compared to most other setback seatposts available. So don't let that signature bend fool you into thinking it offers more than it really does.
 

·
Registered
Joined
·
549 Posts
beeristasty said:
Assuming the same force is applied, a longer stem will 'understeer' compared to a shorter stem. i.e. longer = more stable, shorter = twitchier.
". . .'twitchier' because. . . your weight will shift forward (over the front wheel)" is what I wrote. Maybe I should have emphasized the bike will feel "twitchy" on steeps and downhills (again, because the weight has shifted forward). On flats and uphills, the bike may feel more stable because you're stretched out. I mean, if longer stems meant more stability, wouldn't all the downhillers and freeriders be running 110mm stems? Now, don't get me wrong, I'm not trying to start a war. I suppose stem-length also is dependent on application as well. . . .
 

·
mbtr member
Joined
·
6,503 Posts
If it were me (and i'm big and tall, so maybe it's different) I would rather either add wider bars or raise them, rather than move my seat back. For me, difference between a seat angle that is comfortable to pedal and isn't so far back that its too hard to get behind the seat is very small. Raising the bars helps with knee clearance (and changes a bunch of stuff) and wider bars make the cockpit feel bigger.

I have a thomson layback post, but i wouldn't have gotten it if there were more options in 410mm+ range. I'm at the end of adjustment for downward saddle tip, i can't drop the saddle as far down into the frame because of the kink, and sometimes the kink gets jammed in the frame. It's pretty nice otherwise though.
 

·
Don't touch me!
Joined
·
873 Posts
emptybe_er said:
". . .'twitchier' because. . . your weight will shift forward (over the front wheel)" is what I wrote. Maybe I should have emphasized the bike will feel "twitchy" on steeps and downhills (again, because the weight has shifted forward). On flats and uphills, the bike may feel more stable because you're stretched out. I mean, if longer stems meant more stability, wouldn't all the downhillers and freeriders be running 110mm stems? Now, don't get me wrong, I'm not trying to start a war. I suppose stem-length also is dependent on application as well. . . .
No offense taken - I was trying to say there is a tradeoff between stability and agility (long vs. short stem).
 

·
Registered
Joined
·
1,104 Posts
Given your short height, a layback post would be a great option. You are a little farther weighted forward even with that 72 degree seat angle because your overall seattube length (actual seattube + post) are so short. Putting your seat back would place your weight farther back over the rear tire and provide greater traction. If you have a 30.9 diameter (which I think you do) I have a brand new Thomson Elite layback that I'd sell for $75 shipped if you want. There is a cheaper alternative which is the Ritchey Comp. The post is straight but the mount at the top is pushed back about the same as a Thomson layback. They are decent quality, but of course not nearly as strong or durable. Hope it helps...
 
1 - 15 of 15 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top