Hey guys,

I already have three road bikes and would like to convert one to a hybrid with flat bars. The bike is an Origin 8 Carbon with Ultegra 6700 (10-spd) groupset.
Thanks!

You need new bars, flat bar brakes/shifters. It can be expensive.

I would say its more cost-effective to sell your road bike and buy the hybrid bike you want.

You should consider a drop bar bike geometry may not work well with a flat bar setup.

The cheapest way to convert your road bike, is to install a stem riser and moustache bars. That would give you an upright riding position for not very much outlay and you can keep your road bike drop bar brifters.

I've done this and it's a fun project. As mentioned, a flat or riser bar, shifters and brake levers. Many people scoff at those who do it, but I say go for it. It's much cheaper than going the other way, ie. Flat to drops.
This was a nice one I saw a couple of years ago.

I put Albatross bars on an older Raleigh Pro which made it very squirrelly to ride. Put the drops back on, sold it and bought a hybrid.

Assuming the bike fits you well, easy.

1. Stem: use the one you have, if looking for a more upright position; add 1 or 2 cms. if trying to approximate present fit.
2. Bars: use "mtb" flats, with a bit of back sweep, plus bar ends if trying to approximate present fit. Try other variations, as some mention above, if looking for something different.
3. Shifters: you may have to check. You should still be able to buy the last-generation 770 10 speed shifters. They'll work; the new/current Tiagra 10 spd. ones probably will as well, but you should check that (cable pull).
4. Brake levers: you need flat-bar (mtb-style) levers, but for road caliper/canti brakes, not v-brakes. You can, if necessary, use Avid SD7 levers; they will adjust to work with calipers.

All this can be assembled quite inexpensively. As giantfcr1 points out, costs much more to go the other way.

I had a bike shop do this with a Cannondale CAAD 8 that I bought inexpensively ($400). The conversion cost me about $125 which included parts and labor. I really liked the bike a lot more with flatbars than the drops. I wish the bike had fit me a little better - a bit small - so I sold it for $600. I keep looking at craigslist hoping to find a 58cm road bike that I'd like so I could try the conversion project again.

All you need is flat bars and trigger shifters that are compatible with your derailleur's cable pull and 10spd cog set. Not very expensive and relatively simple.

Buying a new bike is not more cost effective than spending $35 on bars, $100 on shifters and whatever the shop charges you to install. Plus, if you're willing to sell your Ultegra brifters, you could easily get ~$120 bucks back from selling on ebay or CL if they're in decent shape.

Depends on if you like grip shifters....which is the cheapest and lightest option.