stick with JIS or swap to external BB advice

darkhairedlord
darkhairedlord Posts: 7,180
edited March 2013 in Workshop
Hi All,

I have a 2010 trek 1.5 which I ride every day for commuting and weekends for fun. The Chainrings on the compact FSA Vero JIS chainset are coming to the end of life and will be replaced along with the cassette and chain (and my shiney new planet X excelight wheels :wink: ) when I give it a spring service after the salt has gone from the roads.
I can either pop on some new 7075 miche grande tour rings (£40) or some 6061 stronglights (£25) along with a new 103mm JIS Token Bottom Bracket. Alternatively I can ditch the Vero and fit a Tiagra compact and go with an external BB.
The big question is, will the external give me anything better? Will it give me lots of sterling service or am I going to end up relacing bearings every five minutes! Is it going to be less stiff than a standard square taper JIS? is it just emporer's new clothes....

Comments

  • nicklouse
    nicklouse Posts: 50,673
    well if you are going to go External do get the BB shell faced (or at least the tools on to confirm it has been)

    themain thing about the external is thta it is a stiffer set up. Bearing life. generally not as long as good old internal.
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • darkhairedlord
    darkhairedlord Posts: 7,180
    of course..
    if I go with a new chainset I will have spare wheelset, chainset, bb, cables, pedals, saddle. I will just need to upgrade the brifters and bars then I can sneek in a new frame and have n+1
  • nicklouse
    nicklouse Posts: 50,673
    darhlairedlord wrote:
    of course..
    if I go with a new chainset I will have spare wheelset, chainset, bb, cables, pedals, saddle. I will just need to upgrade the brifters and bars then I can sneek in a new frame and have n+1

    Perfect.

    just for get the gears and go SS.
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • islandman
    islandman Posts: 73
    Change as little as you can get away with, you won't notice any difference with external bb except you'll be replacing it more often.
  • darkhairedlord
    darkhairedlord Posts: 7,180
    Cheers, I'll probably order up some new rings and stick with the internal BB system.
    Can I use different brand rings or should they match?
  • ugo.santalucia
    ugo.santalucia Posts: 28,337
    darhlairedlord wrote:
    Cheers, I'll probably order up some new rings and stick with the internal BB system.
    Can I use different brand rings or should they match?

    Brand is irrelevant, distance between bolts is what matters
    left the forum March 2023
  • MichaelW
    MichaelW Posts: 2,164
    The bolt circle diameter (BCD) is critical. Some brands have better ramping and cutouts for sweet shifting, some have none for singlespeed use. Chainring metal varies in hardness a lot. Cheap soft aluminium rings are much easier to chop up with a hacksaw compared to Stronglight Zircal or TA and they also wear out more rapidly.
  • darkhairedlord
    darkhairedlord Posts: 7,180
    Just an update after advice provided; I have bought an FSA 7900 50 tooth from CRC (£20ish) and a Shimano 6750 34 tooth from bikediscount (£7.17)
    I'm not that bothered about the labels matching.. just wasn't sure if there was any lead in machining that would need to align with the ramps/pins on the larger ring for nice shifting. Just need a new BB and I can bolt it on on before the existing bits finally give up. Have to space out the spending as fuhrette might notice the parcels or bank statement.
    In summary, ta for the advice and I might post a picture when I give it a spring rebuild.

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