changing from triple to double
hi, as title I am changing from triple set up to double, I want to go with a compact 50 x 34 and keep my 11-28 cassette as that is new, can I run this configuration with a short cage derailleur or would I still need the long cage option? I have read short cage can do as big as 30t on back and front must be max of 16t between sizes, I am just in on both accounts but wanted to double check before I order, thanks
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should be ok0
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hi, as title I am changing from triple set up to double, I want to go with a compact 50 x 34 and keep my 11-28 cassette as that is new, can I run this configuration with a short cage derailleur or would I still need the long cage option? I have read short cage can do as big as 30t on back and front must be max of 16t between sizes, I am just in on both accounts but wanted to double check before I order, thanks
Yes you will be fine with the current versions of the short cage rear derailleur. As you say they can now cope with a maximum sprocket size of 30 combined with a 50/34 compact chainset. You will have no problems with your 11-28. Just make sure you size the chain correctly - this is quite a handy tool IMHO
http://www.machinehead-software.co.uk/bike/chain_length/chainlengthcalc.htmlhttp://www.machinehead-software.co.uk/bike/chain_length/chainlengthcalc.html
As an afterthought - am I correct in assuming that your triple had a square taper bottom bracket and if so are you changing that to a Hollowtech 2 bottom bracket? The reason I ask is that the square taper bottom bracket widths differ between triple and double/compact chainsets to compensate for the extra third ring and maintain an acceptable chainline. Therefore if you are opting for a square taper compact crankset, you will probably have to replace the bottom bracket also.0 -
hi, my current triple is a hollowtech II one, its also a 105, I forgot to say I do have a medium cage already, could I use that, wanted a short one purely for aesthetics if I am honest
but if a short will do a full range of shifting I would prefer it, not that I would but could you still do big on front and big on back with a short cage? thanks 0 -
slight change of plan after a thought, I got up pretty good hill on Saturday in current middle ring 39t and 2 from biggest at back so a 50-34 chainset will be a little too much, thinking of now using 52-36 with my 11-28 cassette, could I use my medium cage for this or are you better off using short cage, I am not sure of the difference??0
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Depends how steep the hills on saturday were if you can cope with the 36x28....
With a short cage you need to pay more attention to what you shift (chain length is more critical) but it is possible.
I hve a bike with a triple 13-26 and 52-42-30 , short cage no problems.0 -
slight change of plan after a thought, I got up pretty good hill on Saturday in current middle ring 39t and 2 from biggest at back so a 50-34 chainset will be a little too much, thinking of now using 52-36 with my 11-28 cassette, could I use my medium cage for this or are you better off using short cage, I am not sure of the difference??
Yes, your medium cage will be fine. Short cage derailleurs are not that expensive so if you prefer the look of the short cage then go for it. You can always sell on the medium cage if it's in reasonable condition.
Medium cage derailleurs are required to take up the extra chain length when you run a triple or if you fit a larger range rear cassette with a 32 or larger biggest sprocket.0 -
thanks, im gonna keep my medium rear derailleur as its mint for now, another question is do I need to change the BB? I currently have a tiagra holowtech II BB on there, as far as I can see they all the look the same or does it need spacing? do the spacers come with the cranks if so? thanks0
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thanks, im gonna keep my medium rear derailleur as its mint for now, another question is do I need to change the BB? I currently have a tiagra holowtech II BB on there, as far as I can see they all the look the same or does it need spacing? do the spacers come with the cranks if so? thanks
No the Tiagra BB would be fine with any double chainset, including the 52/36 that you are planning to use - no need for any spacers etc. However a new BB is fairly cheap so why not invest in a new Ultegra BB - they're only £14 at Merlin ATM
http://www.merlincycles.com/shimano-ultegra-6800-bottom-bracket-62947.html?utm_campaign=googlebase-GB&utm_source=googlebase&utm_medium=shopping&utm_term=Road+Bike+Bottom+Brackets+%26+Cups&ucpo=15190&gclid=CJDy0r6u78YCFafLtAodkCEOSA0 -
thanks, im gonna keep my medium rear derailleur as its mint for now, another question is do I need to change the BB? I currently have a tiagra holowtech II BB on there, as far as I can see they all the look the same or does it need spacing? do the spacers come with the cranks if so? thanks
No spacers required for a Shimano road double crankset. Your 105 triple will have spacers on both sides, although the drive side one will stay on the axle hidden behind the spider / chainrings when you uninstall it.
If the Tiagra BB still feels smooth, leave it in there and only replace it when it feels clicky / rough. HT2 chainsets are simple things to remove / reinstall when the time comes. Nothing to be gained by replacing a perfectly functional BB prematurely.0 -
thanks, im gonna keep my medium rear derailleur as its mint for now, another question is do I need to change the BB? I currently have a tiagra holowtech II BB on there, as far as I can see they all the look the same or does it need spacing? do the spacers come with the cranks if so? thanks
No spacers required for a Shimano road double crankset. Your 105 triple will have spacers on both sides, although the drive side one will stay on the axle hidden behind the spider / chainrings when you uninstall it.
If the Tiagra BB still feels smooth, leave it in there and only replace it when it feels clicky / rough. HT2 chainsets are simple things to remove / reinstall when the time comes. Nothing to be gained by replacing a perfectly functional BB prematurely.
the current BB is operating flawlessly so I will leave it for now. I was going to ask about the spacer on the non drive side I currently have on the triple crank, one did not come with the new double so I assume not needed?0 -
thanks, im gonna keep my medium rear derailleur as its mint for now, another question is do I need to change the BB? I currently have a tiagra holowtech II BB on there, as far as I can see they all the look the same or does it need spacing? do the spacers come with the cranks if so? thanks
No spacers required for a Shimano road double crankset. Your 105 triple will have spacers on both sides, although the drive side one will stay on the axle hidden behind the spider / chainrings when you uninstall it.
If the Tiagra BB still feels smooth, leave it in there and only replace it when it feels clicky / rough. HT2 chainsets are simple things to remove / reinstall when the time comes. Nothing to be gained by replacing a perfectly functional BB prematurely.
the current BB is operating flawlessly so I will leave it for now. I was going to ask about the spacer on the non drive side I currently have on the triple crank, one did not come with the new double so I assume not needed?
no spacers needed for double chainsets0 -
thanks for confirming, im off work next week so will fit all the new bits then0
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hi, just need to bring this thread up again as I cannot find a definitive answer. I opted for the 52-36 cranks and kept my 11-28 cassette, done a fair few miles since and very happy with range I have, however I dropped my bike yesterday and bent my rear derailleur, I want to replace with new, would prefer a short cage, shimano specs seem to be fine for what I have but I cannot find proof elsewhere it would be ok, ie someone else running this gear config etc. can anyone on here confirm a short cage RD would be ok with 52-36 and 11-28 cassette? thanks0
