Chain length, extra links needed?
 

Hey all. I'm in the process of making my 1x9 roadie into a 1x10. I'm replacing the large 50T chainring with a 52T. Do I need to add any additional links from the chain length I have on the current setup to accommodate the extra 2 teeth? Moving from a Sora 3000 RD to. Tiagra 4700, if that makes a difference. Thank you!

Because the chain only wraps around the front of the chain ring, it only grew by one link (or half a link pair)

the derailleur change will make more of an impact on chain length, if they are of a different roller size and/or arm length or geometry..

best course: put on the new parts and find out.

Quick way to check your existing set up in situ.
If you have an inch slack, you should be good. 3 links would be a bit better.

https://cimg1.ibsrv.net/gimg/bikefor...3948f587ac.jpg

thanks Bill. When I measure, should I have the chain on the smallest cof of the RD?

No, the largest. If that is all the chain slack you have on the smallest cog, you bike might be functionally a 1x3 or even 1x2.

What would that do? You'd have all kinds of slack, so it'd be pointless.
The problem is do you have enoug chain to wrap the TIGHTEST combo.

I think that was just a case of engaging keyboard before brain ;-)

Happens a lot on these here internets

No, I am genuinely limited when it comes to messing with my bikes. Slow learner....

If you are using Shimano stuff, then use their technical document site to read about what they recommend for your specific RD. https://si.shimano.com/

Plug in the RD part number and read the DM or SI. RD-xnnnn


Other brands like SRAM and Campy also have installation and adjustment documentation available on their sites.

or... hang the new parts mentioned, install the chain through the derailleur cage, pull the slack up until the chain no longer hits the underside of the derailleur cage, then note how many links need to be removed from the chain, push the correct rivet out to allow installing the quick link, and put the quick link in.... test the length by shifting the bike into the large rear sprocket carefully, noting if your derailleur will even clear the 52 tooth monster gear you will rarely, if ever, use.

oh, one more thing...both of the derailleurs you mention won't fit a 52 tooth cassette.... unless a wolf tooth der. dropper hanger extension is used... and then, they aren't exactly right, angle wise, and may need serious fiddling to make work.
i'll assume you're using a der. dropper already.

All that might be pertinent if it wasn't a chain ring that the OP was increasing by 2T.

?
explain why argo is changing a rear cassette, and you think "Large Chainring" means he's swapping a SINGLE Front Chainring, when it's obvious that the CASSETTE is being swapped.. "1x9 to 1x10", and a Rear Derailleur is also getting swapped.

calling it "The Large Chainring" is just plain odd, but certainly sounds like a mis-naming of a rear gear/cog/sprocket.
a 46 or larger low gear in back is as big as a chainring, that's for sure!

and, unless the world has gone totally bonkers, the rear der. chosen is still in need of a der. hanger extension, if the cassette is a 10/11/12-52.;)
the tiagra der.will be right at it's max wrap too... 41t.
the b-screw will need set to make up for the extreme angle difference between the der. design and that crazy-steep cassette...

maybe ArgoMan can clear up what EXACTLY he meant by "Large Chainring" in a 1x10 drivetrain.... with only one ring in front.... and the pertinent "swapped" parts clearly mentioned are the cassette and rear derailleur....
if the only size change was the front ring tooth count, why mention the cassette change at all?

I’d guess chainring means chainring in this case, since, on a road bike, a large chainring of 50 teeth is very common, and cassette cogs that low are not. I’m guessing they’re changing the chainring in addition to swapping cassettes from 9 to 10 speed. Maybe they’re actually switching from 2x9 to 1x10 and typoed that part?

OP, you’re probably fine with the current length, though if you’re moving from 9 to 10 speeds you’ll want to install a new 10 speed chain anyway, so you might as well size the new chain with your new gearing installed.

Thank you. I'll look into that.

1x 10-11-12 Road bikes have been around for about a decade now.. some began happening about a decade prior to THAT milestone...... the typical Road front ring is in the neighborhood of 42 to 46, depending on terrain... the 10 sp. cassettes are less expensive, by a margin.
the 10sp, also fits an 8-9-10 freehub, and a 130mm OLD.

etc.

Are you changing both the rear shifter & DER to match.
I think those 2 have different pull ratio's, so you need to swap both.

The only things I planned on changing were the RD (from Sora to Tiagra), the cassette (from 9 to 10), and the chainring (from 50T to 52T.) I got a new 10 speed chain to replace the 9 speed. I use a DA SL-BS77 bar end shifter in friction mode. My research indicated that I can keep the Sora DR (9 spped for index), if I use it in friction only. All I'm really trying to do is to add 2 teeth upfront and an extra cog on the RD.

Edit: ignore that bit, deleted

And does the new 10sp cassette have a bigger largest cog?

I like using the longest chain possible, not the shortest. Doesn't wind the RD cage spring up as much, and leaves margin for when I upgrade the cassette from 30T low to 34T low:

small/small:
https://cimg3.ibsrv.net/gimg/bikefor...7d94002c78.jpg

big/big:
https://cimg4.ibsrv.net/gimg/bikefor...4a035df2b2.jpg

the longest chain possible equals the least wear possible... quicker shifting and less drivetrain drag too.

i learned the small/small technique about 55 years ago.
it works great.:giver:

OK… and what’s your point? Did I suggest somewhere that 1x road bikes don’t exist? :foo:

Yes, I'm going from a 12-23 to a 12-25.

Some old RD's had a low sprocket max of 23. Newer road RD;s 30, 32 and even 34 teeth is common for a low sprocket max. You should know what yours is.

Shimano will tell you in their SI's or UM for the old stuff. And also in the Specifications doc's for all their stuff. Though sometimes it's a pain trying to find if you have to go into the archives and don't know the time period your RD comes from.

Though you can always try it blindly and wonder why it doesn't work and then find the answer. That's not to say that it will not work, but you stand a better chance if you stay within spec.

It’s Tiagra 4700. Will be fine. Another extra link in the chain to go with the one for the chainring though.