I would run exactly what you are talking about except that I need/want a negative stem to ride steeper than the flat sigma stem would allow. So I can't say exactly how well the stem will work (think it would be fine), but I can tell you that I have trimmed the extensions behind the base bar very near to flush with the back. There SHOULD be no structural advantage to leaving extension out the back (assuming you make clean cuts).

If something compromises the integrity of the extension remaining inside the base bar clamp area (like longitudinal cracking due to really crappy transverse trimming of the extension), then that would be a different ball of wax.

Here is my setup, though it currently has much different paint.

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Should be fine to shim it.
God damn that is a nice bar

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Kat Hunter reports on the San Dimas Stage Race from inside the GC winning team
Aeroweenie.com -Compendium of Aero Data and Knowledge
Freelance sports & outdoors writer Kathryn Hunter

Cheers Jim, appreciate the feedback. Good to know. Looks like you and I have the same problem - not enough reach for the frame stack and seat tube angle we like. I'm going to be on my P3C forever I think! One of the reasons I love this Felt bar, it has such low pad stack.

Thanks Jack, good to know. Yeah it is a great bar. That's not mine, I think that is the UCI legal version - mine has an even deeper aspect ratio base bar. Picked it up on ebay for a hundred bucks. It is going to look bang tidy on my P3C when I do the top tube mod and fit the Sigma. My only remaining worry is the tight radius of the downturn from the back of the Sigma to the top tube cable stops. I have the stem fully slammed and I swapped out that massive stock headset cap for a low stack one, so it is going to be fairly tight I think. But looking at the P2 you modded I think it should be ok.

You could probably go with no headset cap at all.
The stem should cover up the bearings pretty well

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Kat Hunter reports on the San Dimas Stage Race from inside the GC winning team
Aeroweenie.com -Compendium of Aero Data and Knowledge
Freelance sports & outdoors writer Kathryn Hunter

Our setups will be very similar when you are done. I got my Devox off of eBay as well. The new version (2013 or so) isn't nearly as low stack as the one you (and I) have, though it is more adjustable.

To get a bar to be this clean and low now, you have to look at the alpha, and to get super low on it, the extensions end up under the bar which I don't think is better than the old devox (plus it costs much more and has been noted to have fit/finish issues).

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That's an interesting thought, I put some Cee Gees on for comfort but was distraught at all that extra pad stack they added. Would be nice if I could get that back and still have all that lavish cushioning. It does rain like a dog over here (West Yorkshire, UK) but the thing pretty much lives on the trainer so would probably be ok.

Cheers again.

yeah and worst case, headset bearings aren't that expensive =)

Plus I prefer them a bit crusty, handlebars don't flop around as much when carrying the bike =)

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Kat Hunter reports on the San Dimas Stage Race from inside the GC winning team
Aeroweenie.com -Compendium of Aero Data and Knowledge
Freelance sports & outdoors writer Kathryn Hunter

Thanks for this thread, my sigma is out for delivery and I completely for got to order a shim for my FSA base bar.

Thank you Amazon prime! :)


Also now I want that Felt bar, very pretty.

Yup it's hard to get that low. I was pretty close before with my Vision Trimax SI aluminium bars - on the clip ons I think you have to keep a small spacer under the pads but on the integrated bars you can mount them directly to the base bar if you can get hold of shorter bolts (or cut down your originals).

What brake levers do you have on yours? I already had the Vision levers which mount externally over the pursuit bars, and was really surprised to find they went straight on over the Felt bars. I had bought some adaptors thinking that the outside diameter would be too big. Did you have to adapt anything? I don't mind the Vision levers, but it's a bit of a bind having to use their proprietory cable set (or use gear cable).

Was delighted when I spotted these Felt badlads on ebay.

Everything thing that Jack said about the cap is correct. I can't speak for the P3, but for the P4, the head tube is not perfectly round, it has a slight point to it. As such, if I get too low with the stem, the negative angle of it will eventually hit the head tube. So I had to find a happy medium between top cap height, negative stem, and head tube clearance. It was an iterative process and I am still not sure that I am 100% finished with it.

I run CeeGees on mine as well, and even though they seem huge, keep in mind that when your weight is on them, they compress a lot, so you are not giving up much stack there (probably less than 0.5 cms).

I run older 3T levers, (http://www.amazon.com/...Levers/dp/B00OUBQGDA). They are very minimal, not the BEST for leverage, but as far as I could find, they presented the smallest profile to the wind. If I were going for a more happy medium, the SRAM levers are pretty good.

Using these levers, the crappy p4 rear brake and the decent omega front brake, I have never feel any trouble stopping. Then again, I am a flat lander. While training in Kona (not on the race course which is fairly mild and rolling) I ended up coming down a VERY steep hill which scared the living crap out of me. I rode the brakes pretty hard after I pooped myself a little and all was well.

If I had conditions like that often, I probably would have a different front, different levers, and probably a different bike with a better read brake.

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As others have correctly mentioned, there's no problem shimming the Sigma XF down to fit a 26mm bar. Regarding stem slamming (no bearings, etc), the Sigma is specifically designed to do that well, it jogs out several extra mm past the bearing diameter before dropping down, as per this geometry image -- http://www.tririg.com/...tallation&num=19 -- specifically to avoid interference. I can't confirm whether you can run it slammed on a P4, but slammed on a new P2 (shown here with a 1mm top cap), it has plenty of room: http://www.tririg.com/..._P2_Review&num=6

Jim - I'm betting you can hit your position with a Sigma XF slammed. Most likely. (And, just between you and me, we may have a solution coming up for people looking for that same kind of ultra-minimal top cap pictured on my P2 above.)

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