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Largest inner ring size available?

ajmitchellajmitchell Posts: 203
edited August 2018 in Road general
Hi, working on a project that requires a large inner ring, almost the size of a normal outer eg 50t,52t. Anyone know if a large inner ring is available ideally 130bcd shimano/sram? If not could a small outer ring be used in the inner position on the chainring or is a ramping tooth profile impossible for that? thanks

Posts

  • MoonbikerMoonbiker Posts: 1,706
    46t I think.

    Not sure about ramps/pins etc

    Whats the project sounds interesting?
  • ajmitchellajmitchell Posts: 203
    its a project looking at finding the optimal gear ratios (without normal assumptions).....btw I have also heard the the tooth difference between inner and outer rings needs to be at least 8t in order to shift, I can test this, but wondering if anyone knew this?
  • trek_dantrek_dan Posts: 1,366
    TA Specialities do some interesting non-standard size chainrings. Spa Cycles seems to have the best choice.
    https://www.spacycles.co.uk/brands/ta.php

    I always thought it was 10 tooth gap for shifting, which is why CX bikes generally have a standard ratio of 46-36.
  • 5858558585 Posts: 206
    I would like to hear a bit more about the aim of the project, could you give some more details?
    There are companies who can make you a set of chainrings in (almost) whatever size you like (eg fibrelyte) but will you be using a particular derailleur/frame or is this some type of lab test? Clearance issues and poor shifting will be an issue in the real world.
    Here is a discussion which is relevant (from a quick google search):
    https://www.bikeforums.net/bicycle-mech ... rings.html
  • MoonbikerMoonbiker Posts: 1,706
    I know they used to push big gears back in the day but 52t inner ring?

    https://www.sjscycles.co.uk/chainrings/ ... chainring/
  • tourdrivingtourdriving Posts: 220
    You can get and 48 here https://www.cyclepowermeters.com/rotor/ ... inner.html
    https://tourdriving.wordpress.com bike hire and travel links, in 47 countries http://ukbikerentals.com UK Bike & Motorcycle hire in Counties after ABC
  • ajmitchellajmitchell Posts: 203
    thanks for all the links, using 130bcd its seems 44, 46 are fairly common 48 available too and above that can be custom made. For those that asked...the project is trying to perfect a new gear selection app which currently (sometimes) calls for some non-conventional combinations. I need to see what exactly is possible on a road bike even if it is not commonly used. thanks again.
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