Paris Roubaix: Old v New v CX

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  • Next weekend @modan and I will be headed out to Flanders to tackle the 235km Tour of Flanders. If that wasn’t interesting enough we decided to mod/build bikes for the event - to see which is better of course!

    ‘New’ bike: I will be modifying my winter training bike - trek domane alr disc

    ‘Old bike’: dan will be building up a steel rossin with dura ace 7700


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  • So while trek would like to suggest that this bike has race pedigree it’s really a hybrid with drop bars and 32c tires to boot. It’s super comfy but with mud guards it weighs a quite incredible 11.9kg! Mod 1 was to get the bars lower so I fitted a Zipp service course SL -17 120mm stem and service course SL 70 ergo bars. The eagle eyed will notice that with the mudguards you can only fit 28c on the front, but there is still room for 32 on the back


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  • The rossin was built up at Brixton cycles today! Full specs:
    Rossin Columbus genius 56cm
    Columbus minimal carbon forks + chris king bearings
    Mavic cosmic elite wheelset
    DA 7700 shifters + deraileurs + brakes
    Pro seatpost and bars


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  • Flanders specific modifications: 105 5700 170mm compact chainset
    11-28 cassette
    Continental 4 seasons 25c tires
    Lizardskin 3.2mm tape


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  • Ok back to the trek. My dwarf legs require me to fit 170mm cranks. So obviously I’ve gone for the most HHSRB option - Rotor 3d+ with aero noQ rings. Now to make life interesting, the trek has a BB89 Bottom bracket (not PF86) listed on the trek website. The fitment is tighter than a ferret’s pocket...


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  • I have to say that the 4130 bearings by rotor are really good quality.

  • Gearing choices.....
    @modan is fairly limited by the rear derailear functional range of DA7700. Guidance suggests the biggest rear cog can be 26 teeth and a range of 26, but we decided to push the envelope as Shimano are always a bit cautious.

    (We looked into a GS version which has more capacity but it’s ultra rare these days)


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  • Now these bikes are to ride up the Belgian bergs, so the starting point really is ‘how slow a gear can we fit?’ And dan decided that 34-28 would be sufficient (more about my choice later). The Sram pg950 fitted the bill nicely. 11-12-13-15-17-19-21-24-28

    Paired with a compact chainset that effectively meant that the smallest cassette cog that was compatable with the deraileur would need to be a rather spinny 18 teeth! Aside from the fact that you can’t buy a cassette like that, most of this issue is overcome by never cross-chaining - in fact it already starts sounding upset when in 50-21. The image below suggests that the optimum chainring shift is 50-19 to 34-13


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  • Cool idea. Hope you have a good time.

    Lots to like about that Rossin. Not sure white tape generally but looks great against the logos on the frame.

  • Yeah dan wasn’t sure either, but white is much more period correct than black.

  • Ok the trek was finished by brixton today. Saddle is too low, but everything else is sound!


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  • This looks promising, subbed.

  • Trek gearing:
    Originally the domane comes with full MAMIL crawler gear. 34-32. It is so slow that I frequently found myself in the next gear up (28) or worse still cross-chaining 50-32 up most of the hills in south London.

    Initially I decided to switch the set up to 1x with something like a 46: 11-40. The logic being that no front deraileur would reduce the chance of chain drops on the flandrian cobbles. Wolf tooth have a chainring designed to fit the Shimano 4 bolt design and the long cage 105 rear deraileur could take a big cassette if a wolf tooth road link.


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  • So 1x was the plan until I went for a ride with a mate that’s also doing Flanders on his CX/Road Specialized crux with 1x. Basically it seemed like the steps between ratios meant he was never in the right gear. While I’m sure he has the perfect gearing to rocket up the Paterberg, the 100km of fast flat before is probably going to kill him! In the end I decided the best compromise would be to do for 50/36 with a 11-30 cassette


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  • Generally a 52/36 11-28 is sufficient for anything here in Belgium. 53/39 is do-able with a Sram PG1170 11-28, which has larger cogs, but only after a bit of training.

    Compacts are just too spinny (for me) on the flats when riding in a bunch.

  • +1

    I was born on one of those bergs (a smaller one, the Kortendries, where Argentin launched his 1990 win - https://youtu.be/vOLLVUxC-hg

    ) and 34 is one of the worst rings to ride Flanders. 36 icw 28 (or 30) is better. Ofcourse, after 150 or more km, freshness may demand other gearing...

    I will ride the bergs a week or two later. On my steel 1990 Master Ariosteia. ;)

    Good look and ride safe!

  • I get it at the top level, but I've never really understood people running out of gears with a 50x11.

    The difference between a 50x11 and a 53x11 is about 5rpm from what I can work out. And a comfortable 90rpm on a 50x11 will have you travelling at a pretty decent 51.5kph

  • Yeah I rode a shorter loop last year on a giant defy with 52/36:11-28. The gearing was ok, but the trek weighs considerably more, and we are doing the full 235km course hence the 30 bailout cog


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  • Agreed! The guy riding the cx bike has 42-11! We all laughed, but we don’t drop him unless we go over 50kph

  • No, you don't need 52 or more. No tourist ever needs 50-11, not even in a bunch going 50-55 km/hr. But the problem is the 34. There is more than flat and bergs, you have lots of parts around 2-5% and on those nor the 34, nor the 50 give a good chain line.

  • I agree! 36 works for me, but will still be interesting to compare the three different gearing approaches on the day.

    @modan took some snaps of this rear deraileur in the extreme positions to check that nothing rubs on anything else. Thankfully Jim at BC is a wizard and got it just right


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  • My experience is: the smaller the steps between gears, the longer you will stay fresh. Every meter you ride in a gear that is a tad too small or too big, is one too many. The drips of energy you waste tbat way, will make the difference between riding or struggling up Koppenberg. ;)

  • Where are you guys staying for the weekend?

  • 4 guys in an Airbnb in Antwerp - about a 10 minute ride from the historic centre. It was good last year and I drank many Kwak beers. I’d love to stay in oudenaarde one year, but I might do LBL in 2019

  • LBL is more my cup of tea. I never really liked the brutal, cobbled climbs in my home region. I always rode in a wide turn around them when going out training. That's why I only did De Ronde once in my life (1999) and there probably won't come a second time. ;)

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Paris Roubaix: Old v New v CX

Posted by Avatar for TheArchitect @TheArchitect

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