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since 4/10/2009
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Discussion Starter · #1 ·
Okay, so I'm building up a road/light dirt commuter built on the On-One Pompetamine frame.

On-One Pompetamine build

I got the medium frame, which has an effective top tube of 541mm. I currently ride a medium 2003 Specialized Stumpjumper FSR Comp that has a top tube length of 574mm. I ride it with a laidback Thomson seatpost (16mm) and a 90mm stem, and it feels pretty dialed.

I will be putting these mustache bars on my Pompetamine, On-One Mungo bars.

On-One Pompetamine build

Reading I have done to this point suggests I will need a shorter stem for mustache bars, but I haven't been able to find anything more detailed than that. Obviously the mtb I currently ride has very different geometry...it has a 71deg head angle while the Pomp has a 73deg angle...and so on, so the geometry that works for me there won't quite be a direct translation to what will work for me on the Pompetamine.

I'd like some kind of general idea of a starting point for stem length when it comes time to do a final fitting of this bike. I am pretty sure I'll have to take it to the LBS and try stems until I find one that fits well, but I'd rather have a starting point for length, at least so I can play a little more with stem angle and overall bar height.

Anyone have any ideas?
 

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Premium Member
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7,402 Posts
I'll throw in my .02. Think the head angle on the new frame will pretty much compensate for the shorter top tube if there's not much rise to, or spacers under stem. Also think a set back seatpost should be used for/is better for adjusting your fit from saddle to pedals. The mustache bars I'd think would put your hands closer together but also further away from saddle, unless you're holding the outside of the bars than prolly the other way around so IDK bout shorter stem.
I personally like to be more upright on a commuter so I can look around better but I mostly live in NYC so?
Think you already know there's no real answer and from where I'm sitting and considering the bars and head angle that around 90mm will get you close and get the bike moving so you can see.
Don't have any, or friends with any, stems that you could try? Or did you just wanna show off your new build? LOL
Up your kilt, let's see some progress pics.
 

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Fat-tired Roadie
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18,453 Posts
You're doing something very, very different from your flat bar MTB, and pretty different from a drop bar.

Your Pompetamine frame is a lot closer in ETT to your mountain bike than my road and mountain frames are. I'd say you want to start with pretty short stems, and work up. Assuming you're planning to spend most of your time out on the hooks on those bars, as described by Grant Peterson. So, maybe an 80mm? Quite short for a road bike. Try to get it cheap. I think you're right about needing to experiment a lot.

Let us know how it goes. I'm a little curious about alternative bars for one of my bikes, that's a bit big for me.
 

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since 4/10/2009
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35,298 Posts
Discussion Starter · #4 ·
Think you already know there's no real answer and from where I'm sitting and considering the bars and head angle that around 90mm will get you close and get the bike moving so you can see.
Don't have any, or friends with any, stems that you could try? Or did you just wanna show off your new build? LOL
Up your kilt, let's see some progress pics.
Yep, I'm just trying to get an idea for where to start so that I don't spent too much time trying stem lengths that obviously won't work. This is something I've been trying to figure out for awhile, but haven't been too sure about. I am a bit anxious to start riding it, of course...I've been collecting parts for a couple months, and now that the frame is here, I wanna build it and ride it. But it'll be another couple of weeks before I have all the parts and can start worrying about a final fit.

Assuming you're planning to spend most of your time out on the hooks on those bars, as described by Grant Peterson. So, maybe an 80mm? Quite short for a road bike. Try to get it cheap. I think you're right about needing to experiment a lot.
Yeah, that's how I was figuring would be the best way to ride these bars. Though I've not read Grant Peterson. I don't anticipate buying stems until I find one I like. I'm planning on doing final fitting at my LBS, where I can hopefully try out stems of different sizes on test rides around the block before I buy anything. Hopefully they'd have cheap stems to try out, so I can walk out the door with a rideable bike, and order the particular stem I want (this is the first bike where I'm going to be picky about the color/finish of my parts). But my LBS is small, so we'll see about that.
 

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With another person to help you you could seat yourself on the bike (when its is assembled) and hold your bars in place and have your helper get a reasonably accurate measurement for stem length, Close enough to start with anyway.
 
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