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I need lower gears to make climbing easier

by Huckfinn
Sat, Jan 26, 2019 18:13
19

Having found the ("pre-loved") bike I'd been looking for for a while:

https://www.giant-bicycles.com/gb/2014-giant-tcx-advanced-1-2014, as per title I'd like to slightly  tweek it for use in the steep hills of South-East France.

Basically: with a setup that has a Cassette SRAM 1050 11-28 coupled with a Crankset Rotor 3DF 36/46 what are my oprions? I'd like to get just below the 1 to 1 ratio for climbing as opposed to the current 36:28=1.28.

Any coment would be appreciated!

 

Huck.

 

If you're new please join in and if you have questions pop them below and the forum regulars will answer as best we can.

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19 comments

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Spangly Shiny | 5 years ago
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WiFli rear mech works fine with a 11/34 cassette, have not tried it with 11/36.

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Huckfinn | 5 years ago
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You are a proponent of the "one step at the time" approach

...wise

thanks for that !

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CXR94Di2 | 5 years ago
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Its not too weird, but I would hold off and just get the 12-36 cassette

 

If in the future you want even lower, look at the FSA Adventure crankset.  That has a 90mm BCD and will take 30t inner chainring

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Huckfinn | 5 years ago
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I will

Thanks!

In the meantime here's response from Rotor:

"..that crank should have a fairly standard BCD... If you are currently running a 36t ring it likely means you have a 110x5 bcd spider on that ring and you can easily put any of our 110x5 bolt chainrings on that spider. We offer down to a 34t chainring that will fit a 110bcd. A 32t ring will not fit on a 110bcd as it is a smaller diameter than the bolts would be" (....as you suggested)

Also: "Yes, you will have no problem replacing the cassette with the 1070."

Cool! Now I'll check with AbsoluteBlack

Concerning the link I posted :https://www.wolftoothcomponents.com/products/giant-cog-for-shimano?varia...

is it just too weird..?

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CXR94Di2 | 5 years ago
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The issue you have with the Rotor crankset is it has 110mm BCD.

Generally that restricts the inner ring to 34t.  Absolute Black do smaller rings, but I cannot find if these rings fit the Rotor crank-hence email enquiry.

The road link is a cheap way to fit a larger cassette whether 11-36 or 12-36.   You might need a slightly longer chain, but fitting cass will make it clear. 

I would approach these steps in this order

Fit 12-36 cass and road link, check and adjust rear derailleur if needed and check all gears are possible. 

 

Once satisfied look into modify crankset. 

 

Email Absolute Black in the meantime for information.

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maviczap replied to CXR94Di2 | 5 years ago
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CXR94Di2 wrote:

The issue you have with the Rotor crankset is it has 110mm BCD.

Generally that restricts the inner ring to 34t.  Absolute Black do smaller rings, but I cannot find if these rings fit the Rotor crank-hence email enquiry.

The road link is a cheap way to fit a larger cassette whether 11-36 or 12-36.   You might need a slightly longer chain, but fitting cass will make it clear. 

I would approach these steps in this order

Fit 12-36 cass and road link, check and adjust rear derailleur if needed and check all gears are possible. 

 

Once satisfied look into modify crankset. 

 

Email Absolute Black in the meantime for information.

For a 5 arm 110bcd crank you can get a 33t Stronglight chainring which I have on an ultegra 6750 crankset. No one does any smaller chainrings singulaly

Or Praxis works do a 48/32 five arm 110bcd chainring set. You have to have the pair as the 32 ring attaches to the 48t outer, it's clever engineering to allow the use of the 32 on 110bcd.

Cheaper than Absolute Black, which I've just bought for my 4 arm Dura Ace chainset in 46/30 format, but the chainrings are lovely

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Huckfinn | 5 years ago
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Ok

Let's forget about that (but, WAIT, what about this?: https://www.wolftoothcomponents.com/products/giant-cog-for-shimano?varia.....)

So the bottom line is 

1- Replace the 36t in the Crankset with a 34t

2- Replace the cassette with Powerglide 12/36

3- Install Roadlink and check chain compatibility

.....That's all, right?

AND/OR: Can I go smaller than 34t in the Crankset? 

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CXR94Di2 | 5 years ago
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Not in 10 speed.  If you wanted more, it then involves new 11 speed shifters derailleur and cassette.

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Huckfinn | 5 years ago
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Thanks for the suggestion!

I'll check with Sram about compatibility.

That would be the Powerglide PG-1070 right? (55Euros is perfectly fine)

Can you get any higher than 36..?

 

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Fish_n_Chips | 5 years ago
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Check the rear mech gear range.

Change the inner ring.

Check chain tension/length/adjust.

Build legs up by intervals up a hill.

Recover and eat well.

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alansmurphy | 5 years ago
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Just as a word of advice, if you're going for more climbing gears you really need to look at your gears past the midway point. I added a 34 or 36t rear cog onto an 8 speed when recovering from injury so had a 34t front and 11/34or36 rear, it was horrible.

 

The jumps between cogs made the next gear up from the easiest ffel like you were climbing in the worlds toughest gear. You either need a 10/11 speed cassette or be prepared to drop the 11t 13t etc. cogs!

 

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Huckfinn | 5 years ago
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"Youve bought bike, modify away"

cheeky

At the beginning you said:"...swap the inner chainring to 34t.  Swap the cass PG1030 11-36 10 speed."

That'd be just fine!

What is the roadlink for (& would I need it even if I kept the existing 36tchainring)?

+

Do you think I'd have to also swap the shifters or whatever the mechanism is called?

 

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CXR94Di2 replied to Huckfinn | 5 years ago
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Huckfinn wrote:

"Youve bought bike, modify away"

cheeky

At the beginning you said:"...swap the inner chainring to 34t.  Swap the cass PG1030 11-36 10 speed."

That'd be just fine!  ok, if 34 inner chainring is sufficient.

What is the roadlink for (& would I need it even if I kept the existing 36tchainring)? The Road Link is a small bracket which lowers the derailleur- allowing bigger cassette to be fitted eg 11-36

+

Do you think I'd have to also swap the shifters or whatever the mechanism is called?   No the shifters stay the same because you are staying with 10 speed.  The bike is currently 10 speed

 

 

See my comments

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CXR94Di2 | 5 years ago
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You would need to email Absolute Black to confirm which of their sub compact chainring fits the Rotor crank .   If they dont fit and you still want 30-36 combination, it will involve crankset change(possible bottom bracket bearings) too.  

 

As per previous thread, its a case of buying a bike and modifications or frameset- build your own.  Youve bought bike, modify away

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Huckfinn | 5 years ago
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Hi,

thanks for that! (by the way, In The Court Of The Crimson King, , brings back nice memories!!).

Anyway, I notice on their page that the WiFli only supports up to 32t. Is that correct?

PS: what about something like the AbsoluteBlack 46/30 sub-compact chainrings. I could replace the current chainrings with that (or maybe just the 36t with any 30t one)?

AND replace as suggested the cassette with a  PG1030 11-36?

30 chainring with 36 at back seems excellent for climbing!!

 

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Spangly Shiny | 5 years ago
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To go lower than 1:1 your ideal option is to fit a WiFli mid cage rear mech. The Wolf Tooth Roadlink will also work but to me is a bit of a hack.

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Drinfinity | 5 years ago
1 like

The SRAM compatibility chart for the Force rear derailleur mid cage suggests the lowest gearing would be 32 on the back. 

https://www.sram.com/sites/default/files/techdocs/gen.0000000004941_rev_b_compatibility_map_2016_road_components.pdf

I’m assuming it’s a mid length cage rather than a short. The SRAM spec sheet unhelpfully doesn’t provide the capacity, so I can’t see if 46/34 and 11/36 would work- it might do, but you would be pushing the boundaries of the reach (big cassette) and range (difference in lowest to highest gear).

A common solution to this problem is to use a SRAM XX MTB rear mech - go for long cage. This is compatible with Force road shifters, and will easily swallow the range.

 

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Huckfinn | 5 years ago
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Hi and thanks again!

The first hurdle will actually be getting the bike here from the other side of the world in one piececheeky, but I have a reasonable hope of getting it done.

Now: 34 - 36 sounds ok to me (could I even get a 32 inner chainring ..?).

But: is the roadlink necessary? Could any reasonably skilled lbs guy do that for me?

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CXR94Di2 | 5 years ago
1 like

Depends on how much lower you might think you need.   You.could swap the inner chainring to 34t.  Swap the cass PG1030 11-36 10 speed.   You probably need a 'roadlink' from Wolf tooth.  

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