Author Topic: Flat bar gravel frame  (Read 1212 times)

6speed

Flat bar gravel frame
« on: September 02, 2022, 07:44:42 PM »
I am considering the idea of building a flat bar road/gravel bike, but am having trouble with the geometry of my options.  Road/gravel frames have a short reach/TT because the long stem and drop bars lengthen your torso to where it needs to be.  My hoods are 130mm farther out from my stem.  I could make that up through a combination of longer TT, longer stem, and conceding a little distance.  However, the only easy way to get a longer reach is by buying a mountain bike frame.  Ignoring all the minor problems with that, the lack of support for large chainrings is a deal breaker. 

So back to gravel frames.  Something with a sloping top tube and the shortest seat tube...then buy the largest size so I get the longest reach/TT possible.  There isn't anything obvious that makes the math work well.



Flying Trunk Monkey

Re: Flat bar gravel frame
« Reply #1 on: September 02, 2022, 11:09:12 PM »
Ever consider a custom Ti frame?

jannmayer

Re: Flat bar gravel frame
« Reply #2 on: September 02, 2022, 11:48:06 PM »
It might be worth taking a look at some of the gravel frames that have more aggressive geometry (long reach, lower stack). If you were to select the size that gives you the stack you want, the resulting reach might work well with flat bars.

I'm not sure if the handling would be ideal, but if would be interesting to compare that to an XC hardtail.

Pedaldancer

Re: Flat bar gravel frame
« Reply #3 on: September 03, 2022, 01:50:48 PM »
The Carbonda 707 is reaaaally a long frame.
I couldn't ride this as a drop bar bike frankly. Would force me to use a 70mm stem and it would be still sporty riding as my road bike.
I have already seen a flatbar build with the 707.

6speed

Re: Flat bar gravel frame
« Reply #4 on: September 03, 2022, 10:18:20 PM »
The Carbonda 707 is reaaaally a long frame.
I couldn't ride this as a drop bar bike frankly. Would force me to use a 70mm stem and it would be still sporty riding as my road bike.
I have already seen a flatbar build with the 707.

Thanks.  That is more the geometry I was thinking.

svanimpe

Re: Flat bar gravel frame
« Reply #5 on: September 04, 2022, 01:55:27 AM »
I was looking into this as well, but couldn't find a suitable frame. Yes the 707 has a longer reach than normal, but it also has a steep head tube angle, so you'll have to fit a long stem and wide handlebars to avoid twitchy handling.

Pedaldancer

Re: Flat bar gravel frame
« Reply #6 on: September 04, 2022, 02:11:50 AM »
I was looking into this as well, but couldn't find a suitable frame. Yes the 707 has a longer reach than normal, but it also has a steep head tube angle, so you'll have to fit a long stem and wide handlebars to avoid twitchy handling.

Frankly, I had a Giant fitnessbike (fastroad model 2018) some years ago . By just looking on the geometry data this was a pure roadbike frame geometry. Including the steep steering angle.  It was not twitchy at all .. it came with a 100mm stem,  in larger sizes it was going up to 120mm.. and then it's not twitchy .    ;)

6speed

Re: Flat bar gravel frame
« Reply #7 on: September 05, 2022, 02:11:29 AM »
While steerer angle (and thus twitchiness) is a consideration, it is secondary to reach/TT length.  My MTB hardtail is 608TT and 402reach, which may be both a hair shorter than I want, but work out well enough with my longish 90mm stem.  I want something overall longer than that for a flat bar road/gravel bike, which is impossible to achieve without sizing up as much as possible or going full custom.  My MTB has a 430mm ST which has my 400mm seatpost almost at its limit, but makes for a super compliant ride.  These obvious considerations are almost absent from gravel sizing, which leaves me few options to exploit trying to find a long reach.

Custom Ti would achieve a long time dream, except I have become accustomed to super light carbon bikes that are only stiff in directions they need to be.

FullCarbonAlchemist

Re: Flat bar gravel frame
« Reply #8 on: September 05, 2022, 02:25:59 AM »
I’m very curious about this too. I currently ride a GT Grade (V1) and am just too badly disabled these days to be bending over drop bars unless they were somehow set up even higher than my current bike…with its very tall head tube and 70mm Thompson stem with positive rise, I’m not sure where to look for something even taller that has actual good handling.

I love drop bars but since I feel like they’re no longer an option without a very exotic unicorn of a bike, flat bar gravel is my future. Don’t really know what to look at for this, since my default is something more like a downcountry 29er hardtail and that would take a lot of the “underbiking” out of the experience. Plus it wouldn’t be very efficient on the road…

cybrsrce

Re: Flat bar gravel frame
« Reply #9 on: September 14, 2022, 06:27:19 AM »
I’m very curious about this too. I currently ride a GT Grade (V1) and am just too badly disabled these days to be bending over drop bars unless they were somehow set up even higher than my current bike…with its very tall head tube and 70mm Thompson stem with positive rise, I’m not sure where to look for something even taller that has actual good handling.

I love drop bars but since I feel like they’re no longer an option without a very exotic unicorn of a bike, flat bar gravel is my future. Don’t really know what to look at for this, since my default is something more like a downcountry 29er hardtail and that would take a lot of the “underbiking” out of the experience. Plus it wouldn’t be very efficient on the road…

There are some big brand options out there to get some ideas about geometry, like the Specialized Diverge EVO and Marin DSX, but it sounds like you may be more comfortable on a fitness hybrid like a Trek FX.  In between a hardtail and a slack gravel bike, I think we would have to put in some effort to find the open frame equivalent.  There is a guy on youtube that built up a flat bar Evil Chamois Hagar that looks like the perfect bike to me but those frames are $2,500 USD and would be hard to hide from my wife :)

I just converted my gravel bike to flat bars because I started getting some numbness in one hand and it was well worth it for comfort.  Still in an pretty aggressive position though but I flipped the 90mm stem to +6 degrees, 9point8 Slack-R to for -1.5 degree HTA, 700mm 18mm rise bars, SQLab bar inners for a little change of hand position, and I just ordered a Winnow FK-G30 fork because it has a flip from 50mm to 55mm offset to try and combat toe overlap.  Bike is a Large 2019 On-One Space Chicken for reference, it is an open mold frame but I don't remember which one.

6speed

Re: Flat bar gravel frame
« Reply #10 on: September 24, 2022, 11:17:26 AM »
I rode a Cannondale Quick and Trek FX yesterday, both in a size large, and both have much too short of a reach for me.  Thinking about my position on the hoods of my road bike today, I would want the flat bar grips to be a little higher and a little closer.  These bikes have them a LOT closer.  If I size up to XL, then the seat tube is longer than I would like. 

Looking at the Carbonda CFR707 geometry, the XL has the same TT and reach as a Cannondale Quick L, but longer ST, so I can't size up from there at all.

The Specialized Diverge Evo geometry says it's longer than any of the above and the ST on a large is still rideable.  This is the geometry leader so far.

A mountain bike frame still gives me the best options for dialing in fit (as long as the HTA is not too slack).  However, then I can't mount a road double crank.