How long is too long? (1)

Triathlon Forum
1

Two questions:

  1. Is there a point where “too long” a stem causes handling issues? I’m thinking of going to 120mm stem or longer, and was wondering if people have experienced handling issues?

  2. Given two frames one being 2 cm too short (reach), and the other being 2 cm too high (stack)…which is better easier to adjust for? I’m leaning towards reach being easier to adjust for than stack given I’m already on a -17 degree, 100mm stem. Is there a general consensus as too which is easier to adjust for?

Thanks in advance,
Ender

2

Back when there was no tt geometry there were plenty of us riding road frames with Seat Shifters and extremely long stems. I had a 150mm Salsa quill MTB stem on my Pinarello and never knew the difference…blisfully unaware? Then again comparing it to today’s frames it may not handle that great. I still ride a 130 on road.

3

Two questions:

  1. Is there a point where “too long” a stem causes handling issues? I’m thinking of going to 120mm stem or longer, and was wondering if people have experienced handling issues?

  2. Given two frames one being 2 cm too short (reach), and the other being 2 cm too high (stack)…which is better easier to adjust for? I’m leaning towards reach being easier to adjust for than stack given I’m already on a -17 degree, 100mm stem. Is there a general consensus as too which is easier to adjust for?

Thanks in advance,
Ender

I’ve got a zillion miles on a 130mm stem with no problems. I believe going really short leads to increased twitchiness.

Hugh

4

Forum name after the main character in Enders Game? haha just noticed this

5

To answer #1:

On a tri/TT bike with a steep effective seat angle - Yes. If your center of gravity is too far forward, you will have handling problems. I know the keyboard warriors will claim only people with crappy bike handling will have issues, but that’s just not correct. Watch a good mountain bike descend, they get their weight back so they don’t flip over the bars. When your weight is wildly forward anyways from a steep tri setup and you can’t move your weight backwards very much, a long stem is only going to increase your chances of an endo or crash. Having the seat further back or a shorter stem keep your weight in a more balance location. An 80 degree seat angle and 130 stem will change your name to EndoWiggan in a hurry.

Road bike - No. It’s near impossible to get your weight dangerously forward (while seated) with a standard road seat angle.

To answer #2.

Neither of those frames fit you based on that info. Maybe some of the high stack issues could be solved with a low stack aerobar like the bottom mount Zipp Vuka Alumina clip on with their new Evo extensions to get the shifters up high enough?

http://zipp.com/_media/images/dynamicproducts/VukaAlumina_Evo_Ext_VukaAlumina_side_110_blw.jpg

6

To answer #1:

On a tri/TT bike with a steep effective seat angle - Yes. If your center of gravity is too far forward, you will have handling problems. I know the keyboard warriors will claim only people with crappy bike handling will have issues, but that’s just not correct. Watch a good mountain bike descend, they get their weight back so they don’t flip over the bars. When your weight is wildly forward anyways from a steep tri setup and you can’t move your weight backwards very much, a long stem is only going to increase your chances of an endo or crash. Having the seat further back or a shorter stem keep your weight in a more balance location. An 80 degree seat angle and 130 stem will change your name to EndoWiggan in a hurry.

Road bike - No. It’s near impossible to get your weight dangerously forward (while seated) with a standard road seat angle.

To answer #2.

Neither of those frames fit you based on that info. Maybe some of the high stack issues could be solved with a low stack aerobar like the bottom mount Zipp Vuka Alumina clip on with their new Evo extensions to get the shifters up high enough?

http://zipp.com/_media/images/dynamicproducts/VukaAlumina_Evo_Ext_VukaAlumina_side_110_blw.jpg

Stop with the bad advice. Anything from 60mm to 150mm will be fine on most tri bikes. I rode about 85 degrees with a 140mm adjustable for 20,000 miles. More importantly, I have fit dozens of folks to stems longer than 110 on tri bike with ZERO ill effects.

7

The handling of a bike (stable/slow vs twitchy/responsive) is a summation of many factors, but the largest ones will be the weight on the front wheel, and the trail. Note that stem length doesn’t fall into either of those, only as much as it allows you to bring your center of gravity forward, and thus put more weight on the front wheel. Standard road bikes used in a standard classic road bike position will be in the area of 40-45% of the total rider+bike weight on the front wheel. When that increases, the bike gets more responsive/twitchy. The problem with going to long stems on tri set-ups is that your CG is closer to the front, regardless, so a longer stem moves your CG forward (unless you’re stretching your arms out past idea, in which case you’re just screwing up your fit).

As to your second question: neither. Get the frame that allows your position while keeping your CG back far enough to stay below 50% weight on the front wheel.

8

I guess the problem stems…haha…get it(sorry I’m lame ) from going from an old P2 to a New P2. On the old P2 I was slammed and using a 100mm, -17 degree stem. On a new P2 it gets tricky because I can fit on a 48 or 51, the problem is the 48 is about 2cm shorter than my old P2 (but similar stack), and the size 51 is about 2 cm higher stack (then old P2)…so which is easier to adjust for? I can use a more negative degree stem to get lower, or a longer stem to get longer…but is one better than the other? Does one provide more adjustability (i.e. greater options). I would prefer to have less stack because then I can possibly pedestal which (JimERO) is more aero.

9

if you ride a tri bike in a way similar to the positions you admire when you see images of pro athletes, your weight is never going to be less than 50 percent on the front wheel. a good front wheel weight is maybe 55 percent when you’re in the aero position.

the way you keep your weight at about 55 percent, or at least less than 60 percent, is by having your pads sit not too far in front of your steering axis. your pads are where you weight the bike (in the front) and if your weight sits too far in front of the steering axis your bike will not handle optimally.

if your stem is 90mm long, fine. if your stem is 140mm long, but you’ve pulled the pads back 50mm (by for example sliding the extensions back in their clamps, assuming the pads are clamped to the extensions) fine. it amounts to the same thing, tho in this case the difference is now in where the pursuit position is, even though the two examples are functionally the same in terms of weight displacement.

dave (findinfreestyle) is a good athlete, he’s a good coach, he’s a really good swim coach, and he seems to be in the “you can get used to anything” camp. if so, he’s right. you can get used to anything. but you can also get used to drinking boone’s farm, thunderbird, and 2 buck chuck. because you can get used to it, is that the same as requring you to settle for it?

one thing i noticed when watching the really good time trialists in richmond this past week versus the guys finishing 2min, 4min, 5min down, is how nice a line that front wheel tracked for the best riders, versus some time trialists who looked like they were doing the paperboy even while riding on the flats. if you want your bike to be a nice, easily, elegant handler you will not have your weight much in front of the steering column. this usually means a stem 25mm or 30mm shorter than you’d use on your road bike.

still, dave’s right. you can ride a long stem on a tri bike. just, as you get more and more into thorny situations, you risk more and more that the bike will not perform as you want. what is a thorny situation? winds when you’re trying to ride a 60mm or even deeper front wheel. descents. descents in windy situations. descents, braking, corning, deep wheels, all at the same time.

10

My real point is that weight distribution should be considered for the “How long is too long” question. Flipping over because of a 130 stem and an 80 degree SA is a silly example. It would be darn near impossible to do this on a road bike (with any length stem) where so much weight is on the rear wheel. I have seen it multiple times on tri bikes though. Who knows if it would have been avoided on a frame with more reach and less stem.

Have you ever measured weight distribution for some of your more extreme client fits? I’m not suggesting it should be standard practice, I’m just curious. There’s been at least one article on here about it.

I don’t believe most people would be comfortable throwing the average AG triathlete on a bike with their (often excess of) weight that far forward with the same effective SA and stem length that you used. Most people would probably have a much higher front end too which would increase the moment arm on the front hub (when braking). You can’t use your example as a very experienced, skilled athlete to make general recommendations to strangers. I don’t try to mimic Kulhavy’s position when racing offroad, because I will never be skilled or flexible enough to need to be that low.

If we’re throwing out n=1 experiences, the “top” Retul fitter in the Chicago area set me up with a BMC TM02 and a 130 stem after saving all my pennies for a year. He had a few other brands, but that was the best fit according to him and the computer screen. Steepest bolt hole on the seatpost and an Adamo about 1-1.5cm from the max extension line. A year and a half later, the steerer tube cracked in half just between the headset cap and stem. I’m very lucky to have kept my teeth in my mouth. Could the leverage from a forward position and long stem have caused that along with our bumpy Midwestern roads? I don’t know. BMC replaced the entire frame with the next size larger that had 20mm more reach. Popped the seatpost from one into the other, identical distance from BB. 110 stem -6 instead of +6 and the handling was significantly better. Absolutely night and day difference in descending and cornering. (Edit: Identical trail between models.)

In no way am I trying to discount your knowledge or experience. I’m not even providing any evidence. There’s just way more to the conversation than pick whatever frame you want and it will likely work with anything 60-150mm.

(Edit: Some very good replies above before I posted this.)

11

My real point is that weight distribution should be considered for the “How long is too long” question. Flipping over because of a 130 stem and an 80 degree SA is a silly example. It would be darn near impossible to do this on a road bike (with any length stem) where so much weight is on the rear wheel. I have seen it multiple times on tri bikes though. Who knows if it would have been avoided on a frame with more reach and less stem.

Have you ever measured weight distribution for some of your more extreme client fits? I’m not suggesting it should be standard practice, I’m just curious. There’s been at least one article on here about it.

I don’t believe most people would be comfortable throwing the average AG triathlete on a bike with their (often excess of) weight that far forward with the same effective SA and stem length that you used. Most people would probably have a much higher front end too which would increase the moment arm on the front hub (when braking). You can’t use your example as a very experienced, skilled athlete to make general recommendations to strangers. I don’t try to mimic Kulhavy’s position when racing offroad, because I will never be skilled or flexible enough to need to be that low.

If we’re throwing out n=1 experiences, the “top” Retul fitter in the Chicago area set me up with a BMC TM02 and a 130 stem after saving all my pennies for a year. He had a few other brands, but that was the best fit according to him and the computer screen. Steepest bolt hole on the seatpost and an Adamo about 1-1.5cm from the max extension line. A year and a half later, the steerer tube cracked in half just between the headset cap and stem. I’m very lucky to have kept my teeth in my mouth. Could the leverage from a forward position and long stem have caused that along with our bumpy Midwestern roads? I don’t know. BMC replaced the entire frame with the next size larger that had 20mm more reach. Popped the seatpost from one into the other, identical distance from BB. 110 stem -6 instead of +6 and the handling was significantly better. Absolutely night and day difference in descending and cornering. (Edit: Identical trail between models.)

In no way am I trying to discount your knowledge or experience. I’m not even providing any evidence. There’s just way more to the conversation than pick whatever frame you want and it will likely work with anything 60-150mm.

(Edit: Some very good replies above before I posted this.)

Oh sorry. I am with you. I dont want to put somebody on a 130 or whatever, but if they bought the wrong bike, it aint the end of the world. I try to keep tri bikes in the 70-100 range if they are pre-purchase fitting with me.

12

Thanks, some great responses above. I guess I should go with the New P2, size 51 and go with a shorter, more negative degree stem. Or does this also affect the handling of the bike?

13

Thanks, some great responses above. I guess I should go with the New P2, size 51 and go with a shorter, more negative degree stem. Or does this also affect the handling of the bike?

You can go short with less worry than long. I think it was at the FIST advanced workshop where we discussed the shortest effective factory stem on the Felt DA bikes was/is like 50mm or something close.

14

I ride a 130 no problemo.

15

Depends on frame geometry and arm pad position, but generally you want the front axle in front of you. I’m on a 120 now, but it’s -35 degree so I’m not much farther out front than a 110.

Overall steering gets slightly slower, which isn’t a bad thing on a TT bike.

16

My girlfriend rides a 150 and loves it. She thinks any longer and it wouldn’t be able to handle it

17

Thanks for all the replies, I’m thinking the 51, with a low stack aero bar and negative stem would be safer :slight_smile:
.

18

My girlfriend rides a 150 and loves it. She thinks any longer and it wouldn’t be able to handle it

Don’t brag too much. That’s less than 6"…

19

Hey, it’s the width right?

My girlfriend rides a 150 and loves it. She thinks any longer and it wouldn’t be able to handle it

Don’t brag too much. That’s less than 6"…

20

I’m on a 51cm P2SL with a 120mm stem. It’s fine under a lot of conditions, but I really notice that there is too much weight over the front wheel on descents if I try to stay in the aerobars. It forces me to come up and ride the bullhorns, and shift my weight back in the saddle a little bit. I also don’t ride with a really forward position, saddle clamp is in the rearward position with the saddle all the way forward on the rails.

Ideally, I’d be on a bike with a 30mm longer front centre. I could also go with a little more stack, but not much more.