Modifying for lower gears
heavymental
Posts: 2,094
in Workshop
I bought myself a Genesis Croix de Fer on ebay to use for touring. It has 10 speed Tiagra but the lowest gear is only 34-32 (28.46"). I'm thinking that I'm going to need a granny gear to spin up long inclines fully laden so am looking at options.
The best option seems to be to buy a 11-42 Shimano cassette and run a Wolf Tooth Goat Link to handle it. That'll give me a gear inch of 21.75 which I'm hoping will be enough.
The other option is to get a BikinGreen 30-46 chainring set but that only gives me a 25.24 on my current 11-32 cassette.
I could go for a 11-34 cassette and have 26.85" on my current chainset.
Or go for both options of a 11-42 cassette and a 30/46 chainset and have a 19.06"! But that means buying new cassette, chainrings and a Goat Link.
Does anyone have any experience of running any of the above systems or have any better ideas?
The best option seems to be to buy a 11-42 Shimano cassette and run a Wolf Tooth Goat Link to handle it. That'll give me a gear inch of 21.75 which I'm hoping will be enough.
The other option is to get a BikinGreen 30-46 chainring set but that only gives me a 25.24 on my current 11-32 cassette.
I could go for a 11-34 cassette and have 26.85" on my current chainset.
Or go for both options of a 11-42 cassette and a 30/46 chainset and have a 19.06"! But that means buying new cassette, chainrings and a Goat Link.
Does anyone have any experience of running any of the above systems or have any better ideas?
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Comments
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I swapped out my 50/34 for a 46/30 and ran it initially with a 11-34 cassette. Finding that a little low even here in Yorkshire I now run a 11-32. However if I were going to go laden I would definitely consider going back to the 11-34 or maybe even 11-36 for a bottom gear of 22.5".0
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I've gone ahead and got the 11-42 with the Goat Link so we'll see how that goes.0
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Update on this for future reference. I bought the Goatlink thing but realised it wasn't compatible so I sent it back and bought a Sunrace dropper. It works fine with the big cassette although my girlfrined jammed it up once by crossing the chain. I had to wrestle the chain off the big cog. It means you have to be a bit careful with shifting but it works fine for me. I've only done a few miles since fitting it as its on my touring bike which I haven't used much recently but I think it should be fine.0
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It won't get you to 42 teeth, but you can get bigger than 34 without third party adapters, it depends which version of Tiagra you have. If it's the latest 4700, that shares the cable pull ration with GRX 10 speed and you can use the RD-RX400 rear derailleur with no mods required. That supports up to a 36T low sprocket.
Shimano compatibility chart confirm this:
https://productinfo.shimano.com/#/com?cid=C-453&acid=C-454
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