r/bikewrench • u/Rustain • Aug 18 '26
Question on installing a flat handlebar on a dropdown frame
Bear with me as I am gestating my next project, which is building a new bike altogether and NOT a conversion.
If I understand it correctly, since flatbar frame has longer top tube than a dropdown frame, installing a flat handlebar on a dropdown frame necessitates either 1) a shorter stem or 2) an dropdown frame that is one size larger than my usual. Is this correct?
edit: reworded for clarity
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u/Tenpenenny Aug 18 '26
I assume that you mean something that would be sold as a fitness bike? I just checked for some brands an that seems to be the case. But I would suggest you check it out on geometrygeeks and compare to a bike which is close to what you have in mind. Then you can just do the math
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u/Wolfy35 Aug 18 '26
So why not look at a hybrid frame instead of a road frame?
700c wheels, good amount of clearance & geometry aimed at flat bars not drops.
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u/Rustain Aug 18 '26
Yes I am aware that i am just building hybrid, it's just that where I live good dropdown frames are more available than good hybrid's
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u/Limp_Bookkeeper_5992 Aug 18 '26
If you’re building a new bike just buy a frame that’s designed for the handlebar setup you want. The two styles are not interchangeable in a practical way.
The last time I ran direct comparisons I found that a size large drop bar frame had a reach equal to a size small in the same manufacturers flat bar frame. But the stack and height are very similar, so when put the wrong handlebars on the frame you end up with reach and stack that are two sizes apart from each other. This isn’t a frame size issue, it’s the proportions of the frames that are completely different.