140/150 stems

[amator]

Back to this TT hypothetical Q again... how many builders actually will advocate going for such a long stem.

My friend made a switch 2 years ago from riding size 57/58 TT bikes with a 120 stem
to a 55 with a 140/150 stem and claims to like the tighter and faster feel of smaller bikes. Watching the pros in Giro and TDF doing so cemented his decison.
In reality, Does this affect the handling or balance of the bike with so much weight fore?[/

[TAW]

The shop I work at sells Specialized stuff, and because of the limited range of size, I see quite a few bikes roll out with stems of 100 or less. Riding these bikes, and other bikes that I have owned where I've traded stems, I personally like a bike size that will allow me to run at least a 120 or 130 stem. It does affect the handling. That's not to criticize those with whom it's necessary to run a shorter stem due to sizing. The limited numbers of sizes some manufacturers produce naturally limit what type of stem and seatpost a person may ride, or how much drop a person can have. To me, that's a shame.

[Tobias]

In reality, Does this affect the handling or balance of the bike with so much weight fore?
Are you certain it makes much difference to weight distribution?

If a rider installs a stem that is approximately 2 cm longer than "normal", but also moves the saddle back because he is riding a smaller frame, then the CG could be exactly the same relative to BBKT or wheelbase.

And if the rider doesn't move the saddle, but installs a longer stem which merely causes him to stretch out more, what actually changes? Isn't it mostly the hands that move forward which takes the arms forward, but not much more than that? If you don't believe me try weighing yourself on a bike while your hands are on the top of the bars, the drops, the hoods, and extended over the hoods. You'll be surprised the difference is not as much as you might think.

Please understand I don't think a 14 or 15 CM stem should ever be used. I think that if a frame is close to being right in size the stem should be "about" 1/5 the length of the top tube. Hence a 55 CM TT should have an 11 CM stem and a larger bike with 60 CM TT probably around 12 CM (more or less, just rough numbers). But never 14 or 15 CM.

[Tobias]

The shop I work at sells Specialized stuff, and because of the limited range of size, I see quite a few bikes roll out with stems of 100 or less.
I'm not sure that bike frame sizes can account for such differences in stem sizes. Most manufacturers offer their frames with less than 2 CM TT increments, which means that stems can be controlled far better than "less than 10 CM" to over 13 CM. Ideal length plus or minus 1 CM should be workable if the LBS doesn't try to move a frame that is the wrong size in the first place. OTOH to be fair to LBS, the needs of the particular customer may require an 8 or 9 CM stem.

[jeffg]

I have two bikes with 57cm TTs and 11 stems, and 2 with 55-55.5cm TTs and 13 stems. Same setback, etc. All work great.

[Dave]

Dropping 2cm in frame size almost always decreases the HT length by 2cm, but the reach difference is often 1cm or less. It might take a 4cm size reduction to get a 2cm each reduction.

Quite often, the chainstay length will be the same or nearly the same on all sizes. It's the reduction in the front-center that increases the weight on the front, not the change in stem length. The stem length has little effect on weight balance. Torso angle also affects the weight balance. Put a scale under ther front wheel and watch how the weight goes up as the torso is lowered. I wouldn't go over 45% on the front when you're in an agressive cornering position.

[amator]

Besides cornering , downhill...... especially when off the saddle climbing , wont your weight be pushed too far foward by the longer 140 stem?

I think the 2-3 longer stem isnt actually all used to extend 2-3 cm longer in effective reach as some of it is used to bring the bars up (86/94 degree stems)

[saab2000]

This is my Look with a 140 stem. They are totally appropriate if your body dimensions can deal with it.
http://farm3.static.flickr.com/2484/3702350500_e8dbb47530_b.jpg

The handling on the Look is nearly perfect and a shorter or higher stem would make it worse.

I'm no expert, but my observation is that most folks would benefit greatly by longer, lower stems. It's not about racing or the 'racer look', but about handling. The bikes we ride aren't La-Z-Boy chairs and shouldn't be treated as such.

[Tobias]

The handling on the Look is nearly perfect and a shorter or higher stem would make it worse. Is this comment meant for you or in general?

[amator]

Dropping 2cm in frame size almost always decreases the HT length by 2cm, but the reach difference is often 1cm or less. It might take a 4cm size reduction to get a 2cm each reduction.

Quite often, the chainstay length will be the same or nearly the same on all sizes. It's the reduction in the front-center that increases the weight on the front, not the change in stem length. The stem length has little effect on weight balance. Torso angle also affects the weight balance. Put a scale under ther front wheel and watch how the weight goes up as the torso is lowered. I wouldn't go over 45% on the front when you're in an agressive cornering position.

Just to get some numbers in....
If I ride a size 54 Pegoretti now with a 120 stem, how much of a difference
would it be if I were to say downsize to a 52 with a 140? stem.
thks

Frame sizing:
http://www.unoimports.com/frame_sizing/emma.html

[avalonracing]

It may be worth noting that in recent years MTBs have been going from having a shorter TT with a longer stem to a longer TT with a shorter stem. It's being done for handling and weight distribution.

[amator]

Im dumping the numbers here to make it more mathematical than shots in the dark.

size 52 : TT= 53.5, HTA=72, STA= 74, setback = 14.3.. 140 stem
Size 54': TT=55, HTA= 73, STA= 73.5, setback= 15.3.. 120 stem
Chainstay length same
Fork rake same.

AFT: Assumption that moving down from 54 to the size 52, i would move my seat backwards by 1cm with the lesser setback ... wouldnt that give me a an extra 1cm in TT whilst maintaing the balance of the rear.

FORE: Because the HTA of the size 52 is 1 degree less, i can also increase the stem length by about 2cm whilst not changing the front centre balance too much.

[Tobias]

Im dumping the numbers here to make it more mathematical than shots in the dark.

size 52 : TT= 53.5, HTA=72, STA= 74, setback = 14.3.. 140 stem
Size 54': TT=55, HTA= 73, STA= 73.5, setback= 15.3.. 120 stem
Chainstay length same
Fork rake same.

If you move the saddle back 1 CM it then makes the effective top tube of the smaller frame 54.5, so by combining with a 2-cm longer stem your overall reach is quite a bit longer.

Something seems wrong with those numbers (just doing math in my head) if meant to compare same bike model in two sizes. It would not surprise me if the smaller bike has a longer front center based on these numbers, and that would seem odd for a manufacturer to offer a larger frame with shorter wheelbase.

Ask yourself how many custom frames are designed around a 14 CM stem? I'd be surprised if 1 percent of custom Serottas are designed based on 14 or 15 CM stems. If my guess is wrong I'm sure someone will jump in and correct me.

[Climb01742]

one other thing to consider: a shorter TT brings the stem bolts closer to your knees. i have long legs and a relatively short torso. when i climb out of the saddle, my knee caps sometimes hit the stem bolts. ouch. longer TTs (and hence shorter stems) move the stem out away from my knees. it's a small thing but if you have long legs, scrapping your kneecaps gets annoying.

[RPS]

....... hypothetical Q again...

My friend made a switch 2 years ago from riding size 57/58 TT bikes with a 120 stem
to a 55 with a 140/150 stem and claims to like the tighter and faster feel of smaller bikes. [/What are the odds your friend is comparing similar or identical bikes? Probably next to none.

What he likes about the smaller frame may have little to do with the longer stem or the frame being smaller. Perhaps the geometry is better suited for him.

[RPS]

Im dumping the numbers here to make it more mathematical than shots in the dark.

size 52 : TT= 53.5, HTA=72, STA= 74, setback = 14.3.. 140 stem
Size 54': TT=55, HTA= 73, STA= 73.5, setback= 15.3.. 120 stem
Chainstay length same
Fork rake same.
As an example, since both bikes have same rake but different head tube angle, the amount of trail must therefore be different (provided same wheel size). Don't you think different trail may make as much or more difference than stem length?

[Dave]

Im dumping the numbers here to make it more mathematical than shots in the dark.

size 52 : TT= 53.5, HTA=72, STA= 74, setback = 14.3.. 140 stem
Size 54': TT=55, HTA= 73, STA= 73.5, setback= 15.3.. 120 stem
Chainstay length same
Fork rake same.

AFT: Assumption that moving down from 54 to the size 52, i would move my seat backwards by 1cm with the lesser setback ... wouldnt that give me a an extra 1cm in TT whilst maintaing the balance of the rear.

FORE: Because the HTA of the size 52 is 1 degree less, i can also increase the stem length by about 2cm whilst not changing the front centre balance too much.

What is missing from this info is the frame's front-center dimension.

When frames are compared for fit, it's always assumed that the rider has ONE particular saddle fore/aft position, relative to the BB, that he wants to maintain.

With this assumption, I first compare the two TT lengths, then correct for the difference in the STA. The 52cm frame has a 1.5cm shorter TT, but the steeper STA on the 52cm increase it's reach by about 4mm, so the net difference is only 1.1cm. The difference in the HTA reduces the reach difference too, but only by 1-2mm. The smaller 52cm frame basically requires one size longer stem to fit the same as the larger 54cm - with the saddle in the same position relative to the BB.

The slack HTA on the 52cm frame should increase the front-center by about 6mm. With the shorter reach, the front-center may only be 5-6mm shorter. To keep the weight balance the same, the saddle might be moved 2-3mm back. Most people would just set the bike up with the same saddle setback (relative to the BB) they always use. The small increase in weight on the front would not be noticeable.

The trail will be larger on the 52cm frame and result in slower steering. With a typical 43mm fork offset, the trails would be 64mm for the 52cm and 58mm for the 54cm. FWIW, my 51cm LOOK 585 has 64mm of trail. I like it for mountains descents, but I have owned frames with both more and less trail.

[amator]

As an example, since both bikes have same rake but different head tube angle, the amount of trail must therefore be different (provided same wheel size). Don't you think different trail may make as much or more difference than stem length?

Valid point... so in this case the smaller bike would have quicker steering due to the slacker HTA

[Dave]

Valid point... so in this case the smaller bike would have quicker steering due to the slacker HTA

Backwards. The smaller bike has slower steering due to more trail, unless a fork with more offset is used.

[amator]

. The smaller 52cm frame basically requires on size longer stem to fit the same as the larger 54cm, with the saddle in the same position relative to the BB.

The slack HTA on the 52cm frame should increase the front-center by about 8mm. With the shorter reach, the front-center may only be 3-4mm shorter. To keep the weight balance the same, the saddle might be moved 1-2mm back. Most people would just set the bike up with the same saddle setback (relative to the BB) they always use. The small increase in weight on the front would not be noticeable.

Very educational Dave.
I only know of one real life example where my friend has two same brand bikes with documented 2cm of TT difference
The facts as far as I know for this example were that He had to set up his saddle close to 9mm on the rails further back on the 52 to get the same position he had on the size 54? ..... couldnt use the same Brooks swift as the rails were too short and got a swallow instead.

As I recall , His biggest fuss was regarding some calculation of stem angle to bring the handlebars further upwards and how a 140mm was only 132mm of effective horizontal reach.

[amator]

Backwards. The smaller bike has slower steering due to more trail, unless a fork with more offset is used.

So to get back the same steering feel as the 54, he should be looking at a 50mm rake fork (vs the 45mm)

This is what I understand from reading..Slack head angles do more than slow the steering response, though.....they also have the effect of slightly shifting the rider's weight rearward, further behind the front axle.

...by virtue of this, would the use of a longer stem shift the weight fore again?

[Dave]

The saddle would have to be moved further back on the post to get the same positon relative to the BB, but a .5 degree difference should only require about 6mm. The exact amount is (cosA-cosB) times the saddle rail height.

Horizontal stem lengths are affected by stem angle. A common 84 degree. 140mm stem has a horizontal length of 137mm.

[Dave]

So to get back the same steering feel as the 54, he should be looking at a 50mm rake fork (vs the 45mm)

This is what I understand from reading..Slack head angles do more than slow the steering response, though.....they also have the effect of slightly shifting the rider's weight rearward, further behind the front axle.

...by virtue of this, would the use of a longer stem shift the weight fore again?

Stem length, by itself, makes very little difference in the front/rear weight balance. The riders arms move forward a bit and the torso angle drops slightly. If the torso angle didn't drop, there would be almost no change in weight balance.

As I noted, the slack HTA only swings the fork forward by 6mm. It takes nearly 10mm to make the weight balance change by 1%.

Saddle position and torso angle have far more effect.

[saab2000]

Is this comment meant for you or in general?

Certainly it works better for me but my comment is somewhat of a generalization. Race bikes are designed to work with the stems lower and a bit longer.

In the end you've got to try different things and see what works for you.

But I see guys in group rides who sit with short riser stems and they tend to be all over the place on the road. Something is unstable in those setups.

[fiamme red]

Certainly it works better for me but my comment is somewhat of a generalization. Race bikes are designed to work with the stems lower and a bit longer.

In the end you've got to try different things and see what works for you.

But I see guys in group rides who sit with short riser stems and they tend to be all over the place on the road. Something is unstable in those setups.As to stem height, look at photos of the peloton from the 1990's and before, and almost all the riders have quill showing (quill being the equivalent of spacers on threadless headsets). Here's Hinault, for example, with lots of stem showing: http://www.velo-club.net/nicolas/hinault1978.jpg.

As to stem length, road stems in 140mm and 150mm were very uncommon until recently. Did bikes from the 70's and 80's handle poorly compared with today's?

[RPS]

But I see guys in group rides who sit with short riser stems and they tend to be all over the place on the road. Something is unstable in those setups.
In those cases could it be the rider and not the setup, or maybe a little of both?

I expect beginners often start with a fairly high position and work down as they become more fit, flexible, and confident. I have an old beater bike with high bars and don't find it more difficult to steer it straight. I honestly think the rider has more to do with it than the bike does.

BTW, I ride a smaller frame size than you, but think I could take your bike and move the saddle forward, shorten the stem, and be able to get the right reach and "exactly" the same weight distribution as you on that bike. That being the case I'd expect your bike would continue to handle very well with a shorter stem. The main difference would be that my CG would be lower due to my size -- but that doesn't hurt handling.

Saab, nice bike by the way.

[cody.wms]

As to stem height, look at photos of the peloton from the 1990's and before



Pros have always been aerodynamic.

The points that connect the saddle, hoods, and bottom of the drops probably hasnt changed much (in relation to each other), but how the stuff between them looks certainly has.

Hinault had more drop from the top of the bars to the hoods (where everyone spends the majority of their time riding) on older bars, and the drops are typically deeper so that the rider's back would be flat when they were in them. Modern bikes have the hoods positioned higher on the bars, and drops (on many modern compact or shallow bars) are higher in space. If you imagine Hinault's bike pictured in the link running modern ergos and deda anatomics (or shallows for that matter), and hes running the stem on top of the head tube.

Thats probably the same position that the majority of GC guys run (absent Basso). Comparing Hinault's postion to a sprinters , such as Cipolinnis or Pozzatos (who have the most drop/stretch out position possible) is an apples to oranges comparison.

Metalurgy has also come along way. In Hinault's time a fist full of post was all you could have, AFAIK. I havent seen an older seatpost (from the 1980s or earlier) that would allow someone to fit a compact frame. Nor have I seen any mega-long stems, but I dont have the largest sample size of that kind of stuff.

Merckx replicated these long positions by having slack seat tube angles and really long seattubes from what I've read. Keep in mind that virtually all pros in this time period had custom made frames. Now, its usually a production bike, and you have to make do.

But I dont think that frames handled poorly in past generations. Just a different way to get the solution. Bikes are not math problems, they are numerous solutions to any geometry problem.

And the stem thing for any one individual is a personal thing. I like to run longer and lower on my current bike, but thats one data point on one bike. If it handled poorly, or it didnt fit, I wouldnt hesitate to change back. Im not hat concerned with the fashion as much as I am the function (although both matter very much to me).


On my old RB-1, which was two sizes two big, i ran a very short stem and the handling suffered. Too much weight on the back wheel. It wasnt possible to get a longer stem on it. It had 3-4 cm longer top tube that I usually prefer. It wasnt a good fit for me.

True French fit bikes (such as Rivendells) take this into account my having a different front end geometry (read like a smaller size) so that the larger frame doesnt handle like garbage.

Ive never had a stem thats too long, but i could easily see it happening for someone that has average or shorter arms, as opposed to my long arms. A massively undersized bike with a 140 stem would probably handle very poorly for someone with short arms.

But stems are very cheap. Ebay seller Abaxo sells Easton stems for about $15 shipped. Its worth buying several sizes around yours (both up and down in length) and seeing what you like.

So much of message boards are random data points. Look at the latex tube thread, or the discussion of Tufo Tubular/Clinchers that happened here and the one across the hall. Preference is preference, nothing more. Its worth figuring out if you like a more stretched out position for yourself.

[Trouble]

It may be worth noting that in recent years MTBs have been going from having a shorter TT with a longer stem to a longer TT with a shorter stem. It's being done for handling and weight distribution.

When you're riding tight trails it would seem appropriate, the guys riding fast CC, AM or DH are still using longer stems... aren't they? Maybe except for DH, it gets them down over the front tire to prevent washing out.
I run a 120 stem on my 29er and the front hooks up much better than the 110 it came with.


This is my Look with a 140 stem. They are totally appropriate if your body dimensions can deal with it.

The handling on the Look is nearly perfect and a shorter or higher stem would make it worse.

I'm no expert, but my observation is that most folks would benefit greatly by longer, lower stems. It's not about racing or the 'racer look', but about handling. The bikes we ride aren't La-Z-Boy chairs and shouldn't be treated as such.

I agree with this too.
Being one who's struggled with fit, I finally (last weekend) went from a 120 to a 130 stem and I am extremely happy (at this point :)). This bike descends so much better, or to say that I have much greater confidence when descending at 40+ mph. The cornering is just a tiny, tiny bit slower, but I don't care about that because it corners more like it's on rails now. And I can ride much longer and I feel more relaxed with less weight on my hands while in the drops. This I can't understand why, which is why I agree with the other poster who says buy a bunch of stems and just try different stuff.

Another time I notice it is when sitting up riding no handed. No twitching around.
Anyway, I'm a longer stem fan... Just sayin.

[fiamme red]

Another time I notice it is when sitting up riding no handed. No twitching around.Why would stem length make a difference when you're riding no-handed?

[Tobias]

Why would stem length make a difference when you're riding no-handed?
For the same reason that one percent change in weight distribution changes how a bike handles.