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Bar and stem length/width ratio

Old 08-12-20, 01:00 PM
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Cortland15b
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Bar and stem length/width ratio

Hello, Iím looking into updating the stem length and bar width on my 1995 Gary fisher Aquila that I plan on adding a quill stem adapter on. It is a 15.5Ē frame that is stock 105mm stem and 560mm bars.

Iím 5í6Ē so a short guy. From the research Iíve done itís a lot about personal preference but the general rule of thumb is 10mm shorter stem for every 20mm wider bars. Following that rule with a 680mm bar gives me a 45mm stem. That seems like a pretty short stem, I was thinking of going with a 60mm stem.

Iíd like to be more stable going down inclines but still overall good handling but Iím not a bike designer so Iím worried about changing the cockpit too much and negatively impacting the ride or the fit of the bike.

I would like to hear what more experienced rigid riders that are on the shorter side have found works best for a bike that has the older geometry (see picture below).



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Old 08-12-20, 01:40 PM
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eshew
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560's are ridiculously narrow. I wouldn't start using your formula until you hit 680. Wider bars are great though & they do slow down steering (fixed by shorter stem) and expand the cockpit. Honestly on that bike I wouldn't go any longer than 80mm ish, no shorter than 65mm. Get the bars & mount em up, you should be able to guess from there. btw, 680mm is still pretty narrow, you could probably go up to 750mm and cut down from there if you wanted. Better chance to fine tune. Get extra cables & housing chances are you'll need em.
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Old 08-12-20, 02:17 PM
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Going to short will make that bike twitchy. It was designed in the long low stem days. I would expect to use something in the 90-100mm range.
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Old 08-12-20, 04:44 PM
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Cortland15b
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Originally Posted by c_m_shooter View Post
Going to short will make that bike twitchy. It was designed in the long low stem days. I would expect to use something in the 90-100mm range.
Thatís what the wider bars are for it slows down the steering the question is will the bars be wide enough to match the stem length I choose.
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Old 08-12-20, 08:06 PM
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Even 20mm can make a pretty big difference in feel on the bike.
I would try an 80mm stem, and a 680mm bar with a 30mm rise. If you don't like the rise, you can also go with a flat bar.
That should make you a lot more confident on the downhills. And it will also be lighter on the hands and wrists.
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Old 08-13-20, 04:53 PM
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Originally Posted by c_m_shooter View Post
. It was designed in the long low stem days. .
^^And short top tube.^^

Buy a new bike. Lots to choose from and so much safer/fun to ride!

https://www.trekbikes.com/us/en_US/b...=bluedark_grey

https://www.bikes.com/en/bikes/growler/2021?tid=72

https://www.pinkbike.com/news/field-...e-comp-29.html

https://www.pinkbike.com/news/specia...-for-2021.html

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Last edited by tungsten; 08-17-20 at 07:13 PM.
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Old 08-13-20, 08:42 PM
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I really think you are overthinking this. What you are reading doesn't really apply to your bike because your head angle, 71 degrees, is so steep no one would build that today. You probably can't slow up your steering enough no matter what bars you use. A slacker HA makes it easier to go downhill and wider bars give more leverage to turn, but the impact of bar width and stem length on modern bikes is so much more important with a 66 degree head angle.

I think you should try a 680mm bar and a 80mm minimum, maybe a 90mm or 100mm stem. If the 680mm is too wide, and it might be, cut it down. I've ridden 560mm and 580mm and both are too narrow, the 560mm is kinda nuts.

I am using 600mm on the 90's bikes with slightly trimmed grips, so my brake and shifter setup from center is probably the same as a 610/620 bar. I could probably go to 640mm if I wanted to. Shortest stem is 100mm. I have suspension forks that are about 20mm longer than spec. No problem with slow steering.

John
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Old 08-15-20, 08:16 AM
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Iíd try a 680 bar and 80mm cheap stem and see how it fits. Will likely need to try other stem lengths. You can always cut the bar down if you donít like it. Few people I know ever go narrower after giving wider a shot. I remember when 680mm sounded crazy wide. Now it feels crazy narrow to me.

When talking about stem/bar changes, I often see 2 two issues conflated:

1- preserving the same handling (how fast it handles)

2- preserving the same fit

These are seldom the same thing. Yes in both cases you will be shortening the stem as you widen the bar, but not the same amount.

In terms of bar/stem configuration, how ďfastĒ the bike steers is mostly a function of how far your hands are from the steer tube.

How the stem/bar ďfitsĒ has mostly to do with how far your hands are from the saddle.

So, when you go with a much wider bar, the stem length that would preserve the handling is shorter than the length that would preserve fit. Since in reality we size to fit, the wider bar usually handles slower despite the shorter stem.

Of course, this is all a bit theoretical, because the reality is that even with the same level of steering quickness, a wider bar and narrow one feel very different. They change how you ride the bike. Also, some times people actually want a different cockpit fit on the bike as they go wider.

And finally.... most people will just adapt to small changes in handling. I think folks fret over this more than they need to. You just need to try it and see what matters and what does not to YOU.

Last edited by Kapusta; 08-15-20 at 08:20 AM.
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