34 cog with new 105?

For discussions about bikes and equipment.
Miguel Evans
Posts: 48
Joined: 15 Jul 2010, 6:15pm

34 cog with new 105?

Postby Miguel Evans » 12 May 2016, 9:27pm

just bought a Croix de Fer with shimano 105 50/34 with 11 speed 11-32. Want to use it mostly for touring, so can I put a 11-34 straight on the back?
thanks

Brucey
Posts: 35850
Joined: 4 Jan 2012, 6:25pm

Re: 34 cog with new 105?

Postby Brucey » 13 May 2016, 12:47pm

I think you can try; if you have enough chain length (to allow the big-big gear to at least run without breaking anything) and 4mm clearance between the mech and the sprocket with a 32 the 34 might work OK.

If you have to wind the 'B' tension screw very far to get enough mech clearance, you may find the shifting on the smaller sprockets gets a bit iffy.

Shimano's specification assumes a certain dropout length; if your dropout is slightly longer than that (many are) you may be able to run 34 with no issues.

cheers
-------------------------------------------------------------------------------
~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~

User avatar
vollerama
Posts: 11
Joined: 24 Mar 2015, 1:28pm
Location: Aldershot, Hampshire, UK

Re: 34 cog with new 105?

Postby vollerama » 13 May 2016, 1:23pm

Hi Miguel

In addition to Brucey, assuming that your Croix is using the 105 RD5800-GS, the docs say that the maximum capacity on that is 37-tooth. Switching to a 11-34 cassette would give you a tooth-difference of 39. I suppose if you were touring then you won't need an 11-tooth top gear so get a cassette with a small sprocket of no less than 13 teeth (I believe 14-34 is easy enough to come by).

Hope this helps.

pickerd
Posts: 104
Joined: 22 Mar 2015, 7:01pm

Re: 34 cog with new 105?

Postby pickerd » 15 May 2016, 7:20am

That 14-34 cassette sounds a good idea. Where can you get that?

I'm a trendy consumer. Just look at my D5803 using Tapatalk

Tom17
Posts: 5
Joined: 16 May 2016, 6:22am

Re: 34 cog with new 105?

Postby Tom17 » 16 May 2016, 6:37am

I had this very situation. A 34 tooth cog worked but it rubbed the top jockey wheel even with the "b" screw all the way out. I fitted a Lindarets Roadlink from 18bikes and the problem was solved. I could have fitted a much bigger cog if I had needed it.

Miguel Evans
Posts: 48
Joined: 15 Jul 2010, 6:15pm

Re: 34 cog with new 105?

Postby Miguel Evans » 17 May 2016, 9:57pm

Thanks Guys
I had to look up the Roadlink thingy, but that certainly is clever! I've decided to toughen up and ride the 32 for now. Will probably go for the 34 when I have worn out the cogs/chain/back.

User avatar
vollerama
Posts: 11
Joined: 24 Mar 2015, 1:28pm
Location: Aldershot, Hampshire, UK

Re: 34 cog with new 105?

Postby vollerama » 18 May 2016, 4:15pm

Hi Miguel

Sorry for the delay, I've been offline for a bit.

I honestly thought that it would be easy enough to find a road cassette with a small sprocket of 13-14 tooth but I've not been able to track one down! Mountain bike cassettes (see SRAM) offer some crazy-big sprockets but they will not work with your 105 mech.

So, yes, impractical advice! You'll get used to the 32-tooth sprocket with practice anyway :)