I just ordered a new bike (CD0.1) and if I want to copy the fit I had on my old bike (which I liked) I would probably need to get a 60 or 70 mm stem. Are there any significant disadvantages to using such a short stem. If so should I just order the size smaller for the bike?
60 might be a little short. 70 sounds short but not unreasonable. a shorter stem will make the bike feel twitchy. i think alot of it is personal prefference. personaly, i feel a little more comfortable handling with a longer stem. i ride a 110mm stem on my tri bike which i think is a little longer than standard. what size stem was on your old bike that you are trying to mimic the fit of?
what size frame?
we use a 70mm stem on a 56 p2 with no handling problems.
if you size down on the frame you may need an undue amount of spacers, so be sure to check the stack.
It’s a size large frame. When I measure the top tube I get 57 cm but on their website they say it’s a 56. The stack is about .5 inches lower than my older Aegis Trident and the reach is about 1 inch longer. The QR is defiantly a long and low bike.
This article makes me think I picked the best size and I should try to get a 60mm stem and use that.
Haven’t had a chance to read the link you posted, but just wanted to say…I switched to a 60 mm stem (have used an 80 and a 100mm) on my size large CD0.1 and it handles just fine. I’m just tinkering with the fit a bit and trying different stems/seat positions, so far I like the shorter stem.
Typically a 100mm stem is the “standard” with anything in the 80-120mm range being normal. With a 60mm stem you might find the handling to be a bit twitchy, but it may be the best option given the long/low nature of the frame you picked.
I went from a 90 to 70. It was twithcy on the first ride. Now, I don’t even notice it.
Typically a 100mm stem is the “standard” with anything in the 80-120mm range being normal. With a 60mm stem you might find the handling to be a bit twitchy, but it may be the best option given the long/low nature of the frame you picked.
I always thought the term “twitchy” was relative to having quicker steering response. If that is the case, that comes with a steeper head tube or a fork with more rake. Either way, pushing the bars away from you, or bringing the front tire closer to you creates faster steering response and a “twitchy” feeling. You will have a slower steering response with a shorter stem… so I wouldn’t think this is “twitchy”, I would think it would be more “relaxed”.
I don’t think I am wrong here…
I just ordered a new bike (CD0.1) and if I want to copy the fit I had on my old bike (which I liked) I would probably need to get a 60 or 70 mm stem. Are there any significant disadvantages to using such a short stem. If so should I just order the size smaller for the bike?
BTW- I just bought a P2 and it had a pretty sweet stem on it that is 60mm. I am using a 100mm stem, so this one is up for grabs. oversized handlebar clamp, 60mm, +/- 6 degree. It is a FSA OS115 stem.
Link: http://www.singlespeedparts.com/stem-fsa-os115-60mm-6d-175-3296.html
PM me if interested.
Typically a 100mm stem is the “standard” with anything in the 80-120mm range being normal. With a 60mm stem you might find the handling to be a bit twitchy, but it may be the best option given the long/low nature of the frame you picked.
I always thought the term “twitchy” was relative to having quicker steering response. If that is the case, that comes with a steeper head tube or a fork with more rake. Either way, pushing the bars away from you, or bringing the front tire closer to you creates faster steering response and a “twitchy” feeling. You will have a slower steering response with a shorter stem… so I wouldn’t think this is “twitchy”, I would think it would be more “relaxed”.
I don’t think I am wrong here…
Longer stems are less twitchy since you have to move the handlebars across a longer arc to turn the wheel the same number of degrees (it’s one factor, headtube angle and fork rake also play a role)…but don’t take my word, here’s a link and the relevant section quoted below:
http://bicyclingaustralia.com/node/17
Cockpit length is an area that a designer can play with fit and handling at the same time. Going towards a shorter stem tends to speed up the steering feel while a longer stem tends to slow down the steering feel. It is no coincidence that so many pro bikes have a really long stem on them. When your office is a bicycle you don’t want a sneeze to dump you on your backside. Using an average length stem in a production bike permits a good fit for the most people, but a custom frame can be built to incorporate whatever handling traits you desire. The Genesis geometry of Gary Fisher mountain frames was a conscious paradigm shift from Gary— a longer top tube and really short stem to move the front wheel forwards and improve handling on steep hills.
Longer stems are less twitchy since you have to move the handlebars across a longer arc to turn the wheel the same number of degrees (it’s one factor, headtube angle and fork rake also play a role)
Ah… so, the stem length is about the area of “sweep” that gets created to cover the same distance. Cool. I love when I learn something new!!!
Here is how I explained it to my wife:
The swing of the wheel is like the swing of a door and the top of the fork is like the hinge. If you bring your stem closer to the fork its like moving closer to the hinge of the door so a smaller movement of the stem/handlebars makes a larger movement of the wheel.
It seems like that could feel “twitchy” to some people. Either way “twitchy” isn’t exactly a scientific term.
I went from a 90 to 70. It was twithcy on the first ride. Now, I don’t even notice it.
This.
Im now down to 60mm on my P3 and it handles just fine
Of course there’s a little more to it. If you have a nee for a long stem then he chances are that you are moving the centre of gravity of the rider forward and so there will be more weight on the front wheel, and that will change the handling, typically making the bike less stable (in terms of wanting to go in a straight line). This effect is slight compared to the offset of the lever distance (ie a 50% increase in lever/stem) from 60mm to 90mm makes little difference in weight distribution. However, Once you get to the 120s, or beyond then the change in weight distribution can get significant on somne frames depending on the geometry, especially on already large frames with steeper head angles to keep the wheelbase in check. Add the reduced rigidity that comes from a 120-140mm stem and all of a sudden then things get a bit more tricky, especially on descents. This is often magnified by the added weight that naturally comes with the riders who are riding the big frames / long stems and now are left with a steep head angle a long stem that has more flex (bars can rotate more degrees from being parallel to the axle) and the added weight on the front wheel.
All the above is just to say that most bike designers will have a ‘sweet spot’ of stem length in mind for any frame/ specific size. You’re best to choose that frame based on distance from saddle nose to bar and drop from saddle to bar (without requiring 60mm of spacers). The length of seat post showing is normally not an issue. It’s the stem length and number of spacers that are critical (IMHO). If the specific bike you’re after doesn’t have a frame that lets you get the drop / reach then no matter how good a frame it is then nowadays there will be another manufacturers frame that will fit you better and overall give you a more enjoyable and efficient ride.
I admit all the above is slightly tangential for someone that has already bought a frame and is erring on teh side of using a BMX stem, but hey life is all about balance 
I’ve had no problems riding a 60mm stem on my first road bike (was 2 sizes too large for me, thanks douchebag LBS). MY MTB actually has an even shorter stem (for a bunch of reasons, I prefer it setup that way).
However, when I put clip-on aerobars on that road bike the first time, I really struggled with the handling. Enough that I only tried it that once.
I ended up selling the bike soon after and so didnt really spend a lot of time riding that 60mm stem + aerobars config, so it is possible that with a few more rides, I could have gotten used to it. So take this for what it is worth.
And no, I am not a doofus on the bike - I consider myself to have pretty good bike handling skills.
However, when I put clip-on aerobars on that road bike the first time, I really struggled with the handling. Enough that I only tried it that once.
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Almost certainly related to adding the weight to the front.
However, when I put clip-on aerobars on that road bike the first time, I really struggled with the handling. Enough that I only tried it that once.
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Almost certainly related to adding the weight to the front.
Indeed - the first time I got on the bars was at around 22mph or so, and I first leaned on with my right elbow. It took me a good 2 minutes to unpucker after the resultant swerve.
Out of curiosity - how much weight do people have on the bars when in the tuck? Just a little or a fair bit?
The idea is that you are fully supported and bracing yourself with the arms / back / top tube to create a rigid triangle and not rely on the core muscles. The amount of actual weight would be dependent on the location of saddle and arm pads in relation to the two wheels. You shouldn’t be thinking about only putting 50% of weight on th arms.
Ok, so not that much different from the way I have it set up for TTs - get in a low/aggressive position, and then put the bars so that my arms support my torso in that position.
The difference would be that I probably need to find a comfier position than my TT tuck for HIM/IM distances.
Good to know - thanks, Duncan.
The stem is just part of the equation…especially on a tri bike. Where the aerobar pads sit relative to the base bar can have a huge impact on center of mass. Some pads are at zero offset, meaning that they sit directly over the center of the basebar, while others are rearward as much as 5cm. Further, often times I see extensions with too large or short of reach from the pad center. In these cases, the rider often adjusts their hand position to the shifter. This, then, incorrectly shifts their center of mass from the proper position. Some fitters have a dogma about stem length with no regard for center of mass. I once visited a shop where the fitter told me that he would never put a 110mm stem on a tri bike. Two things immediately came to my mind: 1. what is the headtube length of the bike? A taller headtube essentially shortens the stem so an 18cm headtube would require a longer stem than a ride with a 10cm headtube (to achieve the same center of mass). 2. What is the pad steback? Sliding the pads rearward 3cm on a bike with a 110mm stem is akin to a zero offset pad on a 90mm stem. My suggestion is to find a position first and then find a bike that fits the position. There are many good fixtures on the market that allow this (Guru, Exit, Veritas, Tiemeyer, etc). Slowman likes the exit fixture. The point is, don’t buy a bike and then make it fit. Rather, find an optimized position and choose the bike that best fits the position.