# Suggestions on used Roubaix frame sizing and year to build flatbar city bike?



## thumper8888 (Apr 7, 2009)

Normally ride a 54 in spesh road racing geometry, and am thinking about hunting down a Roubaix to turn into the ultimate, flatbar city bike.... and the toptube on the 54 will therefore be too short... so I'm trying to figure out whether it would make sense to go with the 56 or 58 Roubaix geometry...

trying to essentially re-create the high-end Sirrus which has a Roubaix-style carbon frame with zertz inserts etc., but which has somewhat different geometry than Roubaix, so the answer isnt obvious as to size.... also, Roubaix experts, would love to hear what year and model would offer best bang for the buck in your mind. Want to keep it light, but am not about to lay out the moola required for current year or last year.....

I have an alloy Sirrus that I have over time converted to the right higher-end mix of components and will just shift it all over, so at this point it shouldn't be a massive investment...partic if I can find one in need of a little paint etc.

thanks much.


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## scottma (May 18, 2012)

What year/size is the Sirrus? You could check the specs and match up the Roubaix geo as best as you can from that (assuming it is the fit you want). I would look for maybe a 2008 - 2009 Roubaix.


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## thumper8888 (Apr 7, 2009)

scottma said:


> What year/size is the Sirrus? You could check the specs and match up the Roubaix geo as best as you can from that (assuming it is the fit you want). I would look for maybe a 2008 - 2009 Roubaix.


Yeah, that's solid, sane advice and frankly the first thing I did, as the carbon sirrus description kind of insinuates its a straightup Roubaix frame they just used to enhance Sirrus offerings because, hey, it was handy.
But I put the geometry charts side by side and they are much, much different. My second thought was that maybe it was close enough that I could figure it out just by looking at top tube length, and I'm still thinking that will of course be they key dimension... but so much was SO different, head tube, stays, of course wheelbase, that it just seemed like some of the other stuff comes into play with the choice.
As a default, though, if I cant figure it out, will just try to work out stack height, reach etc.


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## roadworthy (Nov 11, 2011)

Thumper, we could have a whole philosophical conversation about this...drop bar versus flat...converting a drop bar frameset to flat bar. Biggest disappointment for me about the Sirrus?...top tubes are woefully too short for an advanced recreational fit for spirited riding.
You will want to size up at least two frame sizes...go 58 Roubaix and even then if you prefer a laid out riding position...you will be shy a bit and will depend on amount of pull back on the flat bar you choose and will need a long stem.. I am not one to denigrate flat bar bikes btw...but if building a new bike not for off road and doing a lot of riding, a drop bar makes the most sense. I do a lot of distance riding.
Below is my 'hotrod townie'...Ti 29er. 625mm top tube with 150mm old school Bonty racing stem.
Cockpit is right for me...but contrast this with the 582mm top tube on my 58mm Roubaix.

Don't get me wrong, a Roubaix because of its forgiving standover would make an excellent flat bar hotrod...provided you can create enough top tube length. Nice thing about the Roubaix choice of course is you won't need a riser flat bar because of the tall head tube.
Good luck.
PS: Spesh doesn't make a Sirrus with a long eough top tube for me to obtain a decent riding position and I am only 6'1".


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## thumper8888 (Apr 7, 2009)

That's good stuff.... partic the idea of going really long with top tube...roubaix compact form does indeed help out with the standover and that long head tube, I think it could be ideal for an esoteric city bike if I get the frame size right. I don't really need the damping effect, as its not like I need to soften the ride for short jaunts, but the headtube and mroe upright stuff seems to make it a better choice than say a tarmac sl2...
And yeah, its just for messing around, not serious road riding .... I dont need another drop bar bike bike, quiver is far too large now: venge s-works, merckx axm and a cervelo s1.


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## thumper8888 (Apr 7, 2009)

OH, and that 29er is awesome... surely is fun to be able to run disc brakes on a quick city bike like that, nice approach.
luckily I'm a bit on long side in leg and bit short in torso so maybe that will ease the issue frationally with top tube length.


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