johnknappcc

I've switched to look pedals and had to bump my saddle up a bit. Now, I would like to bump my quill stem up a bit higher (about 1-2 inches).

I'm going to be getting a Nitto Technomic for this task, however, I have a choice of 80mm or 90mm, my current one is 85mm. Should I: more likely go for the 90mm since the extra height will cause the bars to sit back a bit?

This is the way I'm leaning, just wondering if anyone else had a similar situation?

Garthr

If you can understand this chart, it's worth a look. https://www.habcycles.com/fitting.html

The bottom is the good part "To calculate the effect of raising a stem, add 0.96cm of rise for every 1.0cm of quill or steer tube you expose, and subtract 0.30cm of reach."


This does not however, take into the account the riders preference. As you raise the bar, your body raises with it and you're more upright. This may or may not be to your liking. If you still want to hunch over the bars as you did with a lower stem, the you would need a longer one. According to this formula, raising the bar 2cm would need 6mm longer stem, and taken to 5cm(2 inches) it would 15mm. So the longest stem you'd need is 100mm. I think you'd be fine with a 90 or 95mm, as these are very small amounts.

roadfix

Between the two, most definitely.

johnknappcc

Awesome advice Garthr, thank you! This makes a lot more sense than when I was pulling out my TI-85 yesterday.

tellyho

The other thing to know about the Technomic is that it puts your bars WAY up. In other words, if you only want a little extra height, you might want the Technomic deluxe, which is shorter (but still longer than other stems). Especially if you have a smaller bike (as I discovered with my 52 cm Cannondale) with a smaller head tube, you might not be able to get the stem as low as you want - it will bottom out in the steerer (butted at the base).

dobber

A real geek would use a CAD package

johnknappcc

I did to the calculations, although I have them at home, I have a 58cm frame, and so that height shouldn't be an issue.

So true, I'm going to write a C command line program to do the calculations now.

Road Fan

Raising up 2 inches is a huge rise. Are you also planning to change your position, in addition to matching the saddle rise?

If you really only want to ahve the same position with your new pedals, you probably only need around a 1.5 to 2 centimeter rise. If you already have a standard sort of stem like a Pearl or similar, it will end up too high. Technomic has a rise of 19 cm above the insertion line, the Tech Deluxe around 11 cm, and the Pearl around 6, maybe 7. Plus you can run into an issue at the bottom end, if the steer tube constricts near the fork crown, for strength.

I've been through some of this already, so I've pre-geeked it for you, with a pen, paper and Excel.

But I don't think the Technomic is what will make you happy.

Plus, if you want your new bar position to be the same as it was before raising the saddle, you should probably use the same stem extension as you did before the change.

vredstein

https://alex.phred.org/stemchart/Default.aspx
https://www.rideyourbike.com/fitkitstemtable.html
https://www.habcycles.com/fitting.html

johnknappcc

Thank your for the advice, I'm not sure the Deluxe would give me quite the rise I'm looking for (or at least just barely).

I've had this bike since I was too small for it (when I was a kid). As I grew into it (I was still a kid) I didn't really pay attention to the minimum insertion line . . . but I did have the rise exactly where I liked it (just about a centimeter higher than the seat).

However, now I'm a bit more cautious (and don't feel like eating pavement), so I dropped it back down to the min-insertion line (which has about the same specs as the pearl). That drop is 4cm, and it is making my right hand go numb (by the base of the thumb). I think it is a case of putting too much weight on my hands. I do have my saddle properly leveled (in fact I keep it a bit higher in the front).

Here is a picture before I changed the rise back to the min insertion (keep in mind I rode the bike like this for about 10 years). Ahhh, to be young and stupid . . .



By my estimations, the technomic is 225mm long, and the deluxe is 190mm. So at an extra 35mm, I don't think I would bottom out the steerer. The tube (from race to race) is 133mm, the race+headset bolt is another 30mm or so, and I would like 108-110mm of extension above that. So I would have 117mm down into 163mm of steerer, leaving me with about 46mm before bottoming out.

Is 46mm enough, before hitting the butting on the steerer tube?

Road Fan

Can't really answer your last question, but the answer is maybe.

Assuming you have 7 cm above insertion point on your old stem, I think you have teh insertion line about 3 cm above the headset top. If you need to add about 5 cm above that to get back to your school-days position, you could target a new above-headset length of 15 cm. That is only available from a Nitto Technomic. Most people here will advise you to get a larger frame with an extended head tube, by the way. The technomic will then have an in-tube length of 22-15=7 centimeters. You really might have enough clearance in the steer tube for this to work as you expect.

It's usually recommended to make fitting changes a small step at a time. If you want to jump the whole 5 cm at once, the Technomic is correct. If you want to "inch" up to it (sorry), it might bottom out on you; I can't say. With a Technomic deluxe you can start with one cm above teh position you have and week by week scooch it up, giving a smooth acclimation period. Then when you really get the stem over extended (don't recommend it, but I have done this, too, don't tell anyone!), sell the Tech Deluxe and get the Technomic.

Another thought is to have your position checked by a good fitter and get some advice on what might be the causes of your hand issue. It could be height combined with reach, or maybe something else.

operator

Good god that's like 1.5" above min insert...

Grand Bois

A Technomic Deluxe will look like this when at or very near the minimum insertion line. It measures 110mm from the top of the locknut to the top of the stem. A Technomic will go much higher, but it's going to look stoopid. Another thing to consider is that you want a long stem to be strong and only the Deluxe is cold forged.



Another way to get the bars way up is to use a Nitto Dirtdrop. This one has actually been shortened about 1 1/2". It is cold forged.

Pendergast

The Technomic gives you about 6" above the minimum insertion mark. The Technomic Deluxe gives you about 4.5" above the minimum insertion mark. The Dynamic(the aluminum model not the steel Dynamic 37 stem) gives you about 3.25" above the minimum insertion mark. Measured from the min. insert. line to the top of the stem where the bolt is on the Technomic Deluxe and Dynamic. Technomic is an estimate based on the length I've seen listed for it.

johnknappcc

Just so anyone who might be curious, I picked up a Technomic yesterday, way way way too high. Apparently my steerer bottoms out about half way down the headtube. Looks like I'm I'll be picking up a Deluxe.

Grand Bois

You can always shorten the Technomic. If you shorten it too much, you'll be looking for a shorter bolt or a die to cut more threads on the one you have. Been there.

johnknappcc

Yeah, I saw some other threads regarding that . . . might just be easier to shell out the dough, and ebay the Technomic. But, I'm open to the possibility.