Lower gearing

[Cawol]

Hi all.

I have just bought a Genesis Vapour CX type bike (2nd hand) that I believe has been modified slightly from stock. It has Shimano 105 20 speed gears, with a 12-28 cassette, & an Ultegra 50/34 compact chainset.

I live in quite a hilly part of the world & I could really do with giving myself some more lower end gears. I've looked at changing the chainrings & I don't see many options for 110BCD (which I think is what it is). I think maybe I came across a smaller large chainring (i.e. change out the 50 for a 48 or whatever), but I don't think I found a smaller inner chainring to fit (which is obviously the one I need to). So it looks to me like I wouldn't be able to just change the chainrings - I'd have to change the whole chainset?

So then I'm wondering what changes I could make to the rear end.

I can't seem to find an off the shelf 10 speed cassette that goes up to 30 (or ideally 32).

I'm guessing that simply switching to an 11 speed cassette would not actually be that simple.....?

Or the other option I thought of (but again have no idea of the practicalities) - is whether I could modify the ratios on the existing cassette - could I ditch the 11T, shuffle everything down, then add in a 30 or 32T sprocket? In fact I could probably quite happily lose my 2 smallest cogs & add in a 30 & a 32, if that was feasible.

If it was actually doable without virtually rebuilding the bike, I think my favourite option would be to go to an 11 speed cassette, but I suspect there's quite a bit involved in that. But maybe the last option of modifying the sprockets on the existing cassette is the most practicable? Unless someone knows of an 11-30, 11-32, or even 12-30 or 12-32 10 speed cassette that could just be swapped out with the current one.....?

Either way, with any option involving larger sprockets, would I have to change the chain as well?

If anyone is able to shed any light on the practicalities of any of these options, that would be much appreciated!

[meic]

Tiagra come in an 11-32 and an 11-34 10 speed.

http://www.ribblecycles.co.uk/shimano-1 ... #pid=19581

Depending on how they cut your existing chain, it could well be too short.
As the bike is relatively unridden you could get away with not changing it if the existing one was a bit more generous than it needed to be.

I would be inclined to buy a new chain anyway and keep the old cassette and chain as a matched pair for occasional use when things are not so hilly.

[Brucey]

34T is the smallest chainring that fits to a 110BCD crankset, so your options for lower gears are larger cassette sprockets or a different chainset altogether.

BTW if you do get a smaller big ring, do note that your front mech will have a recommended interval between chainrings (eg 14T minimum or whatever) . If you stray away from this value you can expect your front shifts to go bad.

FWIW spa cycles do some nice chainsets which accept smaller chainrings OK.

cheers

[markfh]

Your options for changing the cassette will be determined by which model rear derailleur you have. The last 10 speed version of the "105" rear derailleur comes in two variants the short cage (RD-5701-SS) and mid cage (RD-5701-GS). They are both specified for a maximum front difference of 16T but have different total capacities SS=34T and GS=40T. They also have different maximum low sprocket sizes SS=30 and GS=32 and maximum high sprocket sizes (SS=14T and GS=12T) but have the same minimum high sprocket sizes (SS & GS = 11T). If you want to go for a lower gear than given by either a 30 or 32T rear sprocket you will need to change the rear derailleur. I believe that it is possible to use a 9 speed road or mountain bike rear derailleur with 10 speed 105 shifters and have an even larger rear sprocket but have no direct experience myself. If you do go for a cassette with a bigger largest ring you will need to ensure that the chain is long enough to allow selection of the largest sprocket at the font and rear which may mean that you need a longer chain.

Shimano used to do a 12-30 Tiagra 4600 10 speed cassette which I particularly liked as it had fairly even steps between adjacent gears whereas the 11-32 has a fairly large step between the I think the 2nd and 3rd smallest sprockets. I believe that there is a 12-30 10 speed available in one of the higher groupsets but it is considerably more expensive. It may be possible to mix the two smallest cogs from your existing cassette with the rest from a 11-32. It is something I keep means to try but haven't got round to yet.

[freeflow]

Currently using 5703 sti with a M772 XT 9 speed shadow rear derailleur and a SRAM 12-36 10 speed cassette with absolutely no problems.

[Scunnered]

Or the other option I thought of (but again have no idea of the practicalities) - is whether I could modify the ratios on the existing cassette - could I ditch the 11T, shuffle everything down, then add in a 30 or 32T sprocket? In fact I could probably quite happily lose my 2 smallest cogs & add in a 30 & a 32, if that was feasible.

I do this and it works well. You will need to buy 2 cassettes: one with the largest sprockets you want (32 or 34 teeth) and one with the smallest sprocket and lockring eg 13 teeth. Then to separate the sprockets you first need to drill the head off the 3 pins that hold them together. Finally, select the sprockets you want and mount them on the freehub. It's really easy. I run a 14-32 9 speed cassette constructed in this manner.

[roubaixtuesday]

I recently put an 11-36 on a 105 11 speed using a wolftooth gizmo.

I think the same principle would work for your 10 speed, though a medium or long reach derailleur might be needed.

Still working perfectly 1000ish miles later; Welsh tour featuring Bwylch y Groes is planned on Saturday

Apparently the really important thing is whatever else you do, make sure the chain is long enough to operate in big front/little back, otherwise you wreck everything if you accidentally choose that combo.

Details:
viewtopic.php?f=5&t=113182

[Cawol]

Wow. Thanks guys, for all your replies. That's really helpful.

I recently put an 11-36 on a 105 11 speed using a wolftooth gizmo.

I think the same principle would work for your 10 speed, though a medium or long reach derailleur might be needed.

Still working perfectly 1000ish miles later; Welsh tour featuring Bwylch y Groes is planned on Saturday

Apparently the really important thing is whatever else you do, make sure the chain is long enough to operate in big front/little back, otherwise you wreck everything if you accidentally choose that combo.

Details:
viewtopic.php?f=5&t=113182

BrianFox: I take it your 11-36 cassette is a "MTB" cassette then? Are all the rest of your components (incl chain) "road" components? Does that not create any issues?

Thanks

[Graham]

Apparently the really important thing is whatever else you do, make sure the chain is long enough to operate in big front/little back, otherwise you wreck everything if you accidentally choose that combo.

To clarify :
Chain must be long enough to cope with BIG chainring & LARGEST sprocket selected together.

[Mick F]

Lowering gearing is easy, and you can raise it at the same time.

How?
Fit a Sturmey Archer cassette hub like I've done.
I now have ninety gears ........... triple 10sp and 3sp SA.
http://www.sturmey-archer.com/en/produc ... rf3-silver

Doing this, you keep your existing cassette, your existing chainset and chain, and all your gear controls. All you need is to rebuild your rear wheel.

Sounds complicated, but honestly, it works beautifully. I now have gears from tiny 16" all the way up to astronomical 135"

[old_windbag]

Have scanned through many of the replies. One option i looked at to open up gearing choices with road groupset was below:-
https://www.wolftoothcomponents.com/products/roadlink

This may give ideas to others as an option even if not the OP.

[sjs]

Currently using 5703 sti with a M772 XT 9 speed shadow rear derailleur and a SRAM 12-36 10 speed cassette with absolutely no problems.

Same here, albeit with a more downmarket rear derailleur. I think anything shadow and 9-speed would be OK.

[roubaixtuesday]

BrianFox: I take it your 11-36 cassette is a "MTB" cassette then? Are all the rest of your components (incl chain) "road" components? Does that not create any issues?

The cassette is one of these:

http://www.chainreactioncycles.com/mobi ... prod123725

My understanding is that it matters not whether drivetrain components are nominal mtb or road, but i could well be mistaken.

Graham is of course correct on the big - big point. Not sure how I managed to type the precise opposite of what I was thinking.

Bwylch y groes today hurt a lot, even on 34/36. But not as much as it would have on 34/32

[Brucey]

Have scanned through many of the replies. One option i looked at to open up gearing choices with road groupset was below:-
https://www.wolftoothcomponents.com/products/roadlink

This may give ideas to others as an option even if not the OP.

this allows a larger bottom sprocket, but....
a) it doesn't increase the total mech capacity and
b) the top pulley also ends up further away from the small sprockets in most cases

The first means that it is arguably of most benefit to those wanting to run a 1x system and the second means that the shift performance may not be so good on the small sprockets. Even so it is a handy gizmo.

Currently using 5703 sti with a M772 XT 9 speed shadow rear derailleur and a SRAM 12-36 10 speed cassette with absolutely no problems.

Same here, albeit with a more downmarket rear derailleur. I think anything shadow and 9-speed would be OK.

Probably this has been mentioned already but with this kind of setup you usually need to add a barrel adjuster somewhere in the cable run to the rear mech. IIRC there is only one shadow mech that comes with a barrel adjuster fitted in it from the word 'go'.

cheers

[old_windbag]

The first means that it is arguably of most benefit to those wanting to run a 1x system and the second means that the shift performance may not be so good on the small sprockets. Even so it is a handy gizmo.

Yes like so many get out of jail devices it has its limits. It is ideally for single ring 11 speed systems( must admit that seems like quite a good system for general use.... ). On doubles there are the capacity limits when wanting 40+ rear gear but if say a 44 tooth front ring was available to go with the 34 you could have a nice range of about 23"-108" for perhaps £70 total cost. But even in it's present 50-34 use it may give just that extra amount of low gearing a user might need.

One thing they do state is the benefit of using a chain catcher. I fitted a deda dog fang to a triple setup and it works beautifully for £6. Even though the chain is the correct length the amount of "slack" with a long rear mech when changing can catch you out and drop the chain even with end stops correctly set. The dog fang is handy, dropping the chain off the top ring is easier to prevent with the limit screw but if it does occur it's normally curable on the move, dropping off inner a bit different in my experience.