Shimano 105 Triple gearing options

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Brucey
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Joined: 4 Jan 2012, 6:25pm

Re: Shimano 105 Triple gearing options

Postby Brucey » 29 Aug 2019, 8:41am

there's always more than one way of skinning a cat. Provided the 24-39 shift is tolerable this is certainly the least expensive way of getting a change in the gearing. [BTW the chain will end up about 1/2" lower in the FD cage; not every FD will be happy with this arrangement, and you are in some danger of entering a seventh circle of hell which is getting a FD to work with STIs......]

http://ritzelrechner.de/?GR=DERS&KB=30,39,50&RZ=11,12,13,15,17,19,22,25,28,32&UF=2150&TF=90&SL=2.6&UN=MPH&DV=gearInches&GR2=DERS&KB2=24,39,50&RZ2=11,12,13,15,17,19,22,25,28,32&UF2=2150

you could use a 26T chainring and a 11-36T cassette;

http://ritzelrechner.de/?GR=DERS&KB=30,39,50&RZ=11,12,13,15,17,19,22,25,28,32&UF=2150&TF=90&SL=2.6&UN=MPH&DV=gearInches&GR2=DERS&KB2=26,39,50&RZ2=11,13,15,17,19,21,24,28,32,36&UF2=2150;

there are lots of choices. As it happens you can fit a smaller chainring onto the OPs chainset (with a 74mm BCD fitting) but with later shimano road and campag triples, 30T is your lot. BTW provided chain maintenance is kept up, the expense of the suggested 11s cassette need only be borne once; the most worn sprockets are liable to be smaller ones which can be taken from any cheaper cassette with similar middle ratios.

You can see the intervals with a SRAM11-32 cassette compared with the suggested 13-42 cassette here;

http://ritzelrechner.de/?GR=DERS&KB=39&RZ=11,12,13,15,17,19,22,25,28,32&UF=2150&TF=90&SL=2.6&UN=MPH&DV=gearInches&GR2=DERS&KB2=39,20&RZ2=13,15,17,19,21,24,28,32,37,42&UF2=2150

Both have uneven intervals, but you might prefer either depending on your tastes. Personally I think the SRAM 11-32 10s cassette is (for utility /touring) just daft; it has close intervals where you are unlikely to gain much advantage, and wider spacings where it is more likely to cause maximum irritation.

cheers
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~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~

jr970
Posts: 4
Joined: 28 Aug 2019, 6:16pm

Re: Shimano 105 Triple gearing options

Postby jr970 » 30 Aug 2019, 8:18pm

Brucey wrote:there's always more than one way of skinning a cat. .....

you could use a 26T chainring and a 11-36T cassette;

http://ritzelrechner.de/?GR=DERS&KB=30,39,50&RZ=11,12,13,15,17,19,22,25,28,32&UF=2150&TF=90&SL=2.6&UN=MPH&DV=gearInches&GR2=DERS&KB2=26,39,50&RZ2=11,13,15,17,19,21,24,28,32,36&UF2=2150;

there are lots of choices. As it happens you can fit a smaller chainring onto the OPs chainset (with a 74mm BCD fitting) but with later shimano road and campag triples, 30T is your lot. BTW provided chain maintenance is kept up, the expense of the suggested 11s cassette need only be borne once; the most worn sprockets are liable to be smaller ones which can be taken from any cheaper cassette with similar middle ratios.



Thanks, I'd been playing around with that nice calculator and come to the same conclusion.

I think I'll change the smallest front cog to either 26 or 28, and put a 11/36 cassette on (several seem to be available)....even a 28/36 combination gives me a 20.8 inch bottom gear with that cassette and the next to bottom is 23.4 which is lower than the current 30/32 combination. I will either use an old 9 speed MTB mech or use a drop link on my long cage 105 mech. All of this is seems fairly easy, and not too expensive to experiment with (I already have a spare Deore LX SGS mech) and hopefully will not stretch the capacity of the changers too much. Will be on the SJS site tomorrow to order up the kit!

David9694
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Joined: 10 Feb 2018, 8:42am

Re: Shimano 105 Triple gearing options

Postby David9694 » 30 Aug 2019, 11:18pm

jr970 wrote:
David9694 wrote:I would go the Stronglight route, which will indeed mean a new b/b as well.

Thanks - I'm thinking that might be best. Would you just go for a Shimano BB UN55 or is there something worth spending a bit more on?


UN 55 is what I generally run with Stronglight. The sealed units always seem so darned heavy. The next question - and don’t ask Mr Trial and Error here - is the right mm axle length: long enough so the inner chainring clears the frame by a few mm, the right length so that the middle chainring points at the centre of the rear cluster - I think. There’s probably a ruler and string solution to this, or Park will sell you something for £69 that does it.

I’ve found with the front mech the defining element is setting it just high enough so the inner plate clears the middle ring when shifting to the top ring. You’ll be a few mm above you you 46 or 48t outer chainring. The only issue i’ve had is over shifting at the front on my friction levers. Make sure you carry an 8mm Allen key for those axle bolts.

NetworkMan
Posts: 645
Joined: 25 Aug 2014, 11:13am
Location: South Devon

Re: Shimano 105 Triple gearing options

Postby NetworkMan » 30 Aug 2019, 11:54pm

jr970 wrote:
Brucey wrote:there's always more than one way of skinning a cat. .....

you could use a 26T chainring and a 11-36T cassette;

http://ritzelrechner.de/?GR=DERS&KB=30,39,50&RZ=11,12,13,15,17,19,22,25,28,32&UF=2150&TF=90&SL=2.6&UN=MPH&DV=gearInches&GR2=DERS&KB2=26,39,50&RZ2=11,13,15,17,19,21,24,28,32,36&UF2=2150;

there are lots of choices. As it happens you can fit a smaller chainring onto the OPs chainset (with a 74mm BCD fitting) but with later shimano road and campag triples, 30T is your lot. BTW provided chain maintenance is kept up, the expense of the suggested 11s cassette need only be borne once; the most worn sprockets are liable to be smaller ones which can be taken from any cheaper cassette with similar middle ratios.



Thanks, I'd been playing around with that nice calculator and come to the same conclusion.

I think I'll change the smallest front cog to either 26 or 28, and put a 11/36 cassette on (several seem to be available)....even a 28/36 combination gives me a 20.8 inch bottom gear with that cassette and the next to bottom is 23.4 which is lower than the current 30/32 combination. I will either use an old 9 speed MTB mech or use a drop link on my long cage 105 mech. All of this is seems fairly easy, and not too expensive to experiment with (I already have a spare Deore LX SGS mech) and hopefully will not stretch the capacity of the changers too much. Will be on the SJS site tomorrow to order up the kit!

If you use 11/36 on the back and 50/28 on the front don't forget extra chain since you must be able to run big to big. You may also find the chain goes slack when running 28 at the front and smallish at the back, unless you have a rear derailleur of 47T capacity. You will almost certainly have no trouble with the front derailleur as you aren't changing the big rings.
With 425mm chainstays you'll likely need 112 or 114 links.

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Paul Smith SRCC
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Re: Shimano 105 Triple gearing options

Postby Paul Smith SRCC » 8 Sep 2019, 12:22pm

jr970 wrote:...Downsize the chainrings to maybe something like 46/36/26 ...105 triple front mech


I use 46/36/26 chainrings on my on my own Van Nicholas Yukon, a TA Carmina; although it is a bit of a compromise with a front mech designed for larger chainrings.

To quote the review of my own chainset and ratio choices "care is needed when choosing chain ring sizes, in my case by using chain rings smaller than the front mech’ was designed for does mean I have compromised on how well the front shifting works. Nearly all road bike mech’s are designed for larger overall rings, as you can see the ’mech line does not follow the chain ring’ so the mech’ pushes the chain too far away from where the chain disengages the chain ring. This can and in this case does mean that you don't get such good gear change, more noticeably when changing into the smallest ring. I have got it working just good enough for me, but it is definitely a compromise, I try not to change down under full pressure and if possible not when in the largest rear sprocket, I get a better shift if I am in 3-4th sprocket down as the mech' engages the chain nearer where it was designed to do, as a precaution I have also fitted an ’Overshift Protector’. Worth bearing in mind that each individuals perception as to what is and what isn't acceptable interms of the compromises that need to be made will naturally vary. My own conclusion is that I am prepared to 'fettle' some of the gear changes and sacrifice efficient shifting to achieve the ratios I want, justifiably others conclude that they would rather have the gears work as they should, at the expense of not having quite the ratios they desire."

TA_Carmina_th.jpg

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The utility cyclist
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Re: Shimano 105 Triple gearing options

Postby The utility cyclist » 8 Sep 2019, 5:46pm

An older Shimano 400LX FD I found worked perfectly with 10 speed 5600 STIs and 48/36/24 and would have been fine for 46, The even older FD-6207 is ideal for half step plus granny even though it was designed as a double only. Re Campag, I had a 46/40/24 with 8 speed and front changing was ridiculously smooth in both directions, I had that on a Shorter, wish I'd kept it, the all alu specially made 13-30 cassette was perfect with regards to the ratios, simply delightful to ride.