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Flat bar gravel bike build…. With a twist

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Cyclocross and Gravelbiking (Recreational) This has to be the most physically intense sport ever invented. It's high speed bicycle racing on a short off road course or riding the off pavement rides on gravel like : "Unbound Gravel". We also have a dedicated Racing forum for the Cyclocross Hard Core Racers.

Flat bar gravel bike build…. With a twist

Old 12-10-21, 03:23 PM
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Flat bar gravel bike build…. With a twist

Hi all,
I ‘ve almost completed a mini-project… Although I own a couple of folding bikes and a carbon gravel bike, i wanted something to play around and be able to fit child seat etc. …
so I built a flat bar gravel bike but it is based on a mini velo frameset (2008 dahon smooth hound frame and 2010 smooth hound fork).

I run a 1x9 groupset with:
-45t chainring mated to 11-36T cassette. The gearing (gearinch) is similar to the one on my 11s gravel bike but the 1st and 11th gear is missing; not the end of the world 😋
- The derailleur is Sora currently operated by a alivio shifter. I also have a set of sora dropbar shifter if I wanted to fit flared dropbar (and travel agent for v brakes).

The stem is the 100mm stem I removed from my gravel bike and the bar was 800mm cut down to 600mm. If I find it to twitchy, i will fit a 80mm stem as I think the bar is too far forwards from the wheel hub.

The wheelset is Kinetix comp with 47-406 Kenda… I can also fit some 35-406 slick.

Yes,it has a manual KS dropper post and bracket to pull a tag along kid bike well it’s a Trailgator connected to a frog bike.
the saddle is a fabric scoop (demo part because cheap).






After a test run, it does ride like the other folding bike but it is much more rigid and great to jump curbs.

With the seat down, it is a little a bmx… once the chain-guide is fitted , I’ll be off to a pump track with the kids 😜
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Old 12-10-21, 06:24 PM
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Super cool. Where do you live?
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Old 12-11-21, 01:23 AM
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Originally Posted by shoota
Super cool. Where do you live?
in the Cotswolds in the UK
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Old 12-12-21, 01:48 PM
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I rode it most of the weekend - on and off.

it worked well with the child seat on a gravel ride, was better towing another bike…




​​​​​​​
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Old 12-16-21, 10:19 AM
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i went on a proper pump track and it was good fun and tiring!!!
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Old 12-16-21, 11:17 AM
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what is the seat tube angle and chainstay length? The ST angle looks really steep and the chainstay length really long. Cant tell if thats accurate or just appearance based on the fact that its a mini.
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Old 12-16-21, 11:38 AM
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Originally Posted by mstateglfr
what is the seat tube angle and chainstay length? The ST angle looks really steep and the chainstay length really long. Cant tell if thats accurate or just appearance based on the fact that its a mini.
you are correct, these dahon mini velos have a very long chainstay 395mm; it is almost as long as the chainstay on my gravel (435mm)
head tube is 73deg (I think a 2deg offset headset would make is better)
The wheelbase is about 10mm smaller than the gravel but with 406 wheels, it looks odd.
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Old 12-21-21, 01:33 AM
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Interesting bike.
Thank you for sharing.
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Old 12-21-21, 01:46 AM
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So I went back to a pump track and had fun going around; all this pumping gives a good workout to the upper body… event managed to get some air (small jumps) and while I love going flat out on a XC downhill, I clearly haven t got the same bottle 30yrs later… but i think it would be a bit easier to jump with shorter chainstays… can t have it all 😅
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Old 01-05-22, 05:46 AM
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After a 2 week x-mas "break" , I modified a few things:

# the litepro 170 crankset was replaced for a bmx jet 160 (my gravel is in sram force 165) because I hit the pedals on the bumps. 155 would be better because it would offer more clearance (similar to the gravel bike clearance), but I think the range of motion would be too small.

# As the derailleur has a small cage and no clutch, the chain kept popping off so I added a chain tensioner, a tube attached to the chainstay which holds the chain between the pedal and the pulleys. I'm not a fan but it seems to be the only solution in 20 ". I spoke with microshift as their Advent 9s derailleur has a clutch but the cage is too long and not recommended for 20"

# 44T chainring instead of 48T which would be equivalent to going from 11-36 to 12-39. I will run the 44 when the bike is fitted with gravel tyres and the 48 when it is fitted with slicks (kojak)

# Since it's very muddy, I modified the 47mm 20 "sks. It's not cosmetically pretty but it protects us (kids and me, not the royal one ) well ...

# Instead of using the rear child seat, I moved the small one to a shot gun and he loves it... It much easier and definitely more fun

To give it better off road characteristic and make it less twitchy, I'm thinking about slacking up the headset angle: this kit can be ordered for different length.
https://www.superstarcomponents.com/...le-headset.htm
if I was to fit a 2deg offset using a 135mm kit, in my case, the offset would be 1deg as the headset tube is about 250mm. This would shift the angle from 73 to 72 deg which translates into ~5mm of added rack.
This would give a similar geometry to my gravel bike one.

In the end, it's a nice, fast mini bike that I take anytime I go outside. And best of all, I can easily make "superman" (people laugh a lot)
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Old 01-07-22, 05:26 AM
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Originally Posted by Fentuz
Hi all,
I ‘ve almost completed a mini-project… Although I own a couple of folding bikes and a carbon gravel bike, i wanted something to play around and be able to fit child seat etc. …
so I built a flat bar gravel bike but it is based on a mini velo frameset (2008 dahon smooth hound frame and 2010 smooth hound fork).

I run a 1x9 groupset with:
-45t chainring mated to 11-36T cassette. The gearing (gearinch) is similar to the one on my 11s gravel bike but the 1st and 11th gear is missing; not the end of the world 😋
- The derailleur is Sora currently operated by a alivio shifter. I also have a set of sora dropbar shifter if I wanted to fit flared dropbar (and travel agent for v brakes).

The stem is the 100mm stem I removed from my gravel bike and the bar was 800mm cut down to 600mm. If I find it to twitchy, i will fit a 80mm stem as I think the bar is too far forwards from the wheel hub.

The wheelset is Kinetix comp with 47-406 Kenda… I can also fit some 35-406 slick.

Yes,it has a manual KS dropper post and bracket to pull a tag along kid bike well it’s a Trailgator connected to a frog bike.
the saddle is a fabric scoop (demo part because cheap).






After a test run, it does ride like the other folding bike but it is much more rigid and great to jump curbs.

With the seat down, it is a little a bmx… once the chain-guide is fitted , I’ll be off to a pump track with the kids 😜
I have a minivelo lovefest....wanted to build one for years.
​​is it a gravel worthy machine?
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Old 01-07-22, 07:41 AM
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Originally Posted by thehammerdog
​​is it a gravel worthy machine?
it does for me. You can make it as performant as a aluminum bike.
Mine is top heavy because I have various things to tow and carry kids around but, i could save 1-1.5kg with a std carbon 27.2 seatpost.
i could fit the same ritchey dropbar and run either 1x10 or 2x9.
although I run 20”, the range can be offset thanks to bigger chain ring to match std 700c bike range.

The limiting factor is the brakes, no hydraulic option in my case.
and the 20” may be a little more sensitive to bumps.
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Old 03-21-22, 10:00 AM
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Originally Posted by Fentuz
i went on a proper pump track and it was good fun and tiring!!!
That looks like a track designed by Clark & Kent. I've always been impressed with their stuff.
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Old 03-21-22, 10:44 AM
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Originally Posted by cmc4130
That looks like a track designed by Clark & Kent. I've always been impressed with their stuff.
not sure about Wroughton but the Bomham one is
Bomham flows well
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Old 06-08-22, 09:50 AM
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So, I played a little with this bike and, I found that I needed a better rear brake so I fitted a dual pivot caliper dia comp BMX and it does the job... I ruined several old tyres doing skid challenges with the kids: "who is going to leave the longest tyre mark while skidding on a carpark or in the garvels".

I broke a rear spoke so I fitted a stronger wheel and I tried a 11-40 cassette and I am pleased to report that it works well with a Sora short cage derailleur... the cassette looks rather big on a 406 wheel.



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