Shimano 105 Triple gearing options

[jr970]

Hi

I have a Van Nicholas Yukon which I built up a few years ago with Shimano 105 5600 series triple gearset (10 speed), so 50/39/30 chainrings and I put a 12-32 SRAM cassette on. This gives me a 24.7 inch bottom gear and a 119 inch top gear (which I dont think I've ever used!)

Now I'm those few years older, less fit, and looking at doing Coast to Coast next year and could do with a couple of lower gears to give me some bail-out options on the hills!

The choices I can see are:

1. Downsize the chainrings to maybe something like 46/36/26 (or maybe 46/34/26 to keep the big:middle gap >11 teeth which seems recommended for the 105 triple front mech). I cant see any way of changing the chainset without junking the Hollowtech II BB and going back to square taper BB + something like Stronglight triple chainset (where I can get pretty much any combination of chainring required). Shimano do other Hollowtech triple chainsets but only for their mountain bike Dyna Sys 10 speed which I guess is not compatible.

Is this a sensible thing to do & any things to watch for? I've used Stonglight on other touring bikes before & they seem bullet proof and very flexible gearing wise, not sure about changing the BB back to a traditional one?

3. Just fit a 26 small ring to the existing chainset. This exceeds the quoted front mech capacity (20 teeth) but some posts seem to indicate it might work & is low cost, it does give a pretty big jump down from 39 middle & I cant go lower than 38 middle ring on the current chainset.

2. Go for a wider rear cassette, maybe 12-36 if I can find one. This needs a bigger range rear mech, but I have an old (9 speed) XT long cage mech which might work. Not sure how good the changes will be with the 105 shifters....

I guess the 3rd option is to convert from drops to straight bars and use gears and changers from a newer shimano MTB groupset like deore XT in which case I have loads of options ?

Any suggestions (and yes I know "lose weight and get fitter" is the best option )

[David9694]

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

[jr970]

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?

[NetworkMan]

If your chainset has 130 mm and 74 mm BCD you should be able to fit chainrings of 48T and 38T on the 130 mm BCD. and 24-28T on the 74 BCD. I have a Spa Ti Audax running 48/38/28 9 Speed with ancient Shimano STI shifters. This changes gear fine. I also have a tourer with 48/38/24 and 8 speed bar end shifting. There is really no reason why you can't drop the size of the smallest ring two or even 4 teeth below the recommended 20T difference; there is a possibility that the chain may touch the bottom of the cage if you try to run small front to small rear and you may also find the chain goes slack but if you avoid the (say) 3 gears at this end of the cassette there is unlikely to be a problem. IIRC both my FDs are intended for 50/39/30 as is yours. One is a Claris 8 speed, the other a Sora 9 speed.

If you like this idea I can provide further info on checking suitability of 24T inner for example.
PS There is no reason why you shouldn't change the chainset to a 110/74 BCD one with square taper - that's what mine are - it's just that changing rings only will be cheaper. You could buy Spa Zicral rings for example

[slowster]

With regard to NetworkMan's comment "you may also find the chain goes slack but if you avoid the (say) 3 gears at this end of the cassette there is unlikely to be a problem", I think that your 9 speed XT long cage rear derailleur would be compatible with your RH 10 speed STI shifter, so you've already got the solution to that problem.

[freeflow]

Several options exist.

1. 11-42 cassette but this gives changes of 14-20% between sprockets. I don't find this an issue riding alone, but when riding with others the group speed can leave you in an awkward cadence.

2. Custom 13/14-29 cassette from Miche

3. Replace your 30 tooth chainring with a 22 tooth chainring

4. Chinese MTB chainset from eBay 44/32/22 or deore 9/10 speed chainset. You need to check your chainline and accept that your front shifter will be much more than 3mm above your large chainring and will likely be at or close to its limit for the large chainring.

I've used all four solutions on my bikes and find they work well enough with only a small amount of care.

Of course, I may have just had very favourable frames.

In general I was using 6603 or 6703 front mechs.

[whoof]

I've changed the 30 to a 26 on a couple of Shimano triple road chainsets without any problems with changing*. The gap from 39 to 26 is quite big but if you just use the inner as a bale out and change to a couple of smaller sprockets first I've never found it a problem.
* This was with 12-27 cassettes for touring in the Alps. I did need to make an adjustment in the B screw on the rear.

I suppose it depends if you want it just for this ride or a permanent change. If it's the latter then the Stronglight route might be better.

[NetworkMan]

I've changed the 30 to a 26 on a couple of Shimano triple road chainsets without any problems with changing*. The gap from 39 to 26 is quite big but if you just use the inner as a bale out and change to a couple of smaller sprockets first I've never found it a problem.
* This was with 12-27 cassettes for touring in the Alps. I did need to make an adjustment in the B screw on the rear.

I suppose it depends if you want it just for this ride or a permanent change. If it's the latter then the Stronglight route might be better.

Trouble is that 30->26 is only about 15% which I call one gear and the OP wanted two. To do that you probably need 30->24. The 24->38 shift is certainly not seamless - I don't double shift and couldn't with barends really, but I'm so relieved at having got to the top that I don't care if it takes me a few seconds to get running on middle again and anyway I'm not racing!

[Brucey]

your XT 9s mech will work OK with the 10s shifters, so you may as well use that, perhaps with a gear hanger extender if you go well over 36T.

The 11s sprocket you have with most 10s cassettes is pretty much useless; it gives you a gear you can pedal (pointlessly) down steep hills.


In 10s cassettes there is no such (useful) thing as a 13-42T cassette but at one time you could buy a replacement #1 sprocket and you would ditch one of the smaller ones to make a useful cassette.

Today , it might make more sense to start with an 11s cassette and to modify that. Shimano 11s sprocket pitch is nominally 3.9mm, vs 3.95mm for 10s. This isn't quite close enough to always work 'as is' but it is pretty close, and a few shims/spacers ought to get you there.

For example CS-M7000-11

https://si.shimano.com/pdfs/ev/EV-CS-M7000-3984A.pdf

can be had in 11-40, 11-42, 11-46T combinations.

In each case the largest three sprockets come mounted to a carrier and can't be respaced, but the other sprockets can be respaced, using shims, as necessary. You can cut shims from coke can using scissors. So using shims you can put the #3 sprocket in the right place and the #1 position is defined by the mech stop screw, not the shifter. This leaves you potentially with a 0.05mm error in position on the #2 sprocket. I think you will be able to live with this; after all you may end up with a 0.1mm shim on every other loose sprocket rather than 0.05mm on every single one, and it should work OK.

Anyway the idea is you ditch your (useless) 11T sprocket and respace the remaining 10 sprockets cassette as necessary, which may include a spacer to make up the length and different lockring perhaps. Note also that if the 13T sprocket doesn't have serrations on it then some threadlock on the lockring is a good idea.

I shall generate gear ratio comparison for your old and new gears so you can see what is going on. FWIW I still think you will get some small-small slack running even with an MTB 9s mech but I don't think that is the end of the world.

cheers

[Brucey]

gear ratios with 11-32 cassette and 30-39-50 chainrings vs 13-42 cassette and the same chainset here

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=30,39,50&RZ2=13,15,17,19,21,24,28,32,37,42&UF2=2150

the result is two extra lower gears as required.

The setup also has super chainlines onto useful gears on the big ring, and ought to be noticeably more efficient/smoother running than setups using smaller chainrings/sprockets.

cheers

[Valbrona]

I use a 105 5600 triple FD and it will not do 36 middle and 46 outer - the cage catching on the middle ring as it moves outward.

Instead, I run 36 middle with 48 outer. I guess 46 outer with 34 middle would probably work.

FWIW My 26/36/48 works fine. I have tried a 24 inner at times but found it unsatisfactory.

You do not have to go back to square taper. I use an Interlock Racing Design tripleizer chainring on an otherwise double chainset.

Check out Miche Triple 110/74 BCD which has integrated axle.

Check out SRAM Wide Axle and FSA Wide Axle for disc brake but also gives triple chainline. These are all 110/74 BCD cranksets that will take aforesaid tripleizer middle ring.

[jr970]

gear ratios with 11-32 cassette and 30-39-50 chainrings vs 13-42 cassette and the same chainset here

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=30,39,50&RZ2=13,15,17,19,21,24,28,32,37,42&UF2=2150

the result is two extra lower gears as required.

The setup also has super chainlines onto useful gears on the big ring, and ought to be noticeably more efficient/smoother running than setups using smaller chainrings/sprockets.

cheers

Thanks - that looks a good solution, something around 20ins is ideal for a super-low gear and 104ins should be fine for top. I'll certainly investigate this option which presumably means a custom cassette. BTW - nice tool for working out ratios, a bit more sophisticated than the Sheldon Brown one.

Thanks to all the other suggestions, I think the other option is to go back to a taper-crank BB + TA or Stronglight triple, and then it's easy to play around with chainring sizes - possibly 46/34/24 or 48/36/26 as suggested. I'd rather keep balanced ratios on the chainset than have big gaps, and as I'm into my 60s now I suspect that this will be long term rather than just for one trip.....

I used to run an 8 speed tourer with very wide ratios and bar-end shifters, I sometimes wonder if I should have stayed with that rather than get involved with STI !

[Brucey]

Thanks - that looks a good solution, something around 20ins is ideal for a super-low gear and 104ins should be fine for top. I'll certainly investigate this option which presumably means a custom cassette. ... !

see my other post immediately prior to the one with the ratios in it.

cheers

[Psamathe]

....... Go for a wider rear cassette, maybe 12-36 if I can find one. This needs a bigger range rear mech, but I have an old (9 speed) XT long cage mech which might work. Not sure how good the changes will be with the 105 shifters.......

I got theTiagra 4703 chainset which has the same front as you already have but runs a 11-34 cassette. Shimano don't support that configuration (the 34 on the cassette) but the LBS reckoned it would be OK so I went for it and it was fine (no slack on the chain). I did offer to lose the 11 on the cassette as I'd never use it but that was not necessary.

Of course that does not give you the 36 you were talking about.

Ian

[The utility cyclist]

By far the easiest is to swap for a 24T inner, the front mech will do this no problem at all and still work with a 50T ring, never had issues shifting up or down to a 39.
Using a 23 means you don't have to start messing about with silly wide ratio cassettes that cost more, give bigger jumps between the ratios themselves and you can keep your existing chain and mechs.