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Will Tiagra RD-4700 work well with 36T rear cog?

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Will Tiagra RD-4700 work well with 36T rear cog?

Old 07-22-17, 07:49 AM
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valueaudio
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Will Tiagra RD-4700 work well with 36T rear cog?

Anyone with real world experience running a Tiagra 4700 rear derailleur with an 11-36 cassette? Capacity is stated at 34 teeth in rear. I know generally Shimano is conservative and people do run larger by adjusting the B-screw to allow room for a larger cog.

Reason for the change is that I'm converting my road bike to 1x in front, and would like a little more low range to go with the larger front ring - probably a 38T, or maybe a 40T. Also, the all-steel Tiagra cassette is very heavy, and I can lighten up about 4-5 ounces by going to 10 speed SLX or XT cassette, which Shimano shows as compatible with Tiagra up to 34T. I'll have no problem with total capacity limits.

I know on my new bike that after I adjusted the B-screw to run the cage closer to the cogs (it shifted lousy out of the shop), my shifting improved quite noticeably. So I'm wondering if I set B-Screw to back off to fit the 36T, if it might adversely affect the quality of the shifting in other gears. Hence, looking for someone who actually compared them, preferably to going up from an 11-34.

Trying to stay away from Wolftooth extensions, derailleur swaps, etc.. Thinking I may eventually switch from Tiagra to SLX shifter, SLX 11-speed derailleur, 11-speed 11-40 or 11-42 and 11-soeed chain to handle the more hilly rides. That's too much outlay though for now.
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Old 07-22-17, 08:19 AM
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Who would know what DR you have without a picture? Long cage? short cage?
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Old 07-22-17, 09:31 AM
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I'm somewhat interested in this topic as well (the prices on the 4700 hydraulic groupset are very tempting, but I need lower gears), so I searched and found a couple of Youtube vids showing the 4700 RD (I assume medium cage/GS) working with 11-36 Deore cassettes:

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Old 07-22-17, 10:02 AM
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It works with my Di2 ultegra derailleur, which is a priori less likely. My wife has your derailleur, and there is a lot of room for the B-screw to be adjusted, so my guess is that the rear derailleur can handle it. (I am about to try it on hers, fwiw, and am confident enough to plop down $50 on a cassette.) You need to be a little more careful with cross-chaining (why not keep the current crank?), and it would be a good time to replace the chain, too, and keep an extra link or two.

Last edited by wgscott; 07-22-17 at 10:05 AM.
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Old 07-23-17, 01:16 AM
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valueaudio
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Originally Posted by trailangel View Post
Who would know what DR you have without a picture? Long cage? short cage?
Tiagra GS - Medium cage. The 34 tooth rear cog capacity was a pretty good clue.
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Old 07-23-17, 01:21 AM
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valueaudio
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Originally Posted by Metaluna View Post
I'm somewhat interested in this topic as well (the prices on the 4700 hydraulic groupset are very tempting, but I need lower gears), so I searched and found a couple of Youtube vids showing the 4700 RD (I assume medium cage/GS) working with 11-36 Deore cassettes:

https://www.youtube.com/watch?v=TJUCf2ey-9c
https://www.youtube.com/watch?v=4s_N9CUGXAw

Thanks for finding those. In the first video, I could hear what sounds like the upper pulley knocking against the teeth when he's on the 36 cog. He apparently has no idea how to set his B-screw.

The second video is much more helpful, and it shows he's still getting real smooth shifting. There's a little knocking when he's on the 36T, but he's showing he has the pulley well cleared, so it's something else. Maybe limit adjustment is off, or chain line is too much for it.

Last edited by valueaudio; 07-23-17 at 01:25 AM.
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Old 07-23-17, 01:32 AM
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Originally Posted by wgscott View Post
It works with my Di2 ultegra derailleur, which is a priori less likely. My wife has your derailleur, and there is a lot of room for the B-screw to be adjusted, so my guess is that the rear derailleur can handle it. (I am about to try it on hers, fwiw, and am confident enough to plop down $50 on a cassette.) You need to be a little more careful with cross-chaining (why not keep the current crank?), and it would be a good time to replace the chain, too, and keep an extra link or two.
Please post here and let us know how the 11-36 is working out on your wife's bike.

I have had a city bike since 2009 with a 1x9, and really love the simplicity of shifting with the 1x. Its got a 39T in front, and an 11-34 in the rear, and works out great - I can climb the steepest hill I encounter around town with it. Its been the perfect gear range for that bike. This Giant Fastroad I've got is the fist 2x I've had in years, and I hated shifting it. Right in the range I use the most, I'd have to shift front rings to avoid ross-chaining hitting the front rings or derailleur, and frequently needing to attend to trim the front D.

I'm keeping the current crank, and just changing the ring. It's an FSA Omega with the lousy 19mm spindle BB, which isn't the best. Like many CX bikes, it's got a 5 bolt 110 BCD. FSA put some offset to the outside on their standard large ring, and I found out if I use the outer (most left) position with a non-offset ring, I'm getting a perfect chain line. No problems showing up with cross-chaining.

For now, I'm using what was the inner ring - a 34 tooth. I figured it was a good way to give it a try and see how I liked a 1x on this bike. It's working very nicely. Just looking for a more range now. Might try an oval narrow-wide, such as Absolute Black, though they are expensive!

Last edited by valueaudio; 07-23-17 at 01:44 AM.
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Old 07-25-17, 03:37 PM
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Originally Posted by valueaudio View Post
Please post here and let us know how the 11-36 is working out on your wife's bike.
It just arrived and I just put it on and it works fine on the stand, even with the old chain. I had to crank down the B-screw pretty much all the way, but it shifts though the gears fine. I can't use big-big, but I haven't put the new chain on (which will be longer). Everything else is smooth. I'll take it for a shake-down ride and post back if anything goes wrong.
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Old 07-27-17, 04:48 PM
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Thanks for the update! I've heard of people adding a longer B=screw to set the cage back further. I imagine going too would move the cage too far from the rest of the cogs to shift well, so I wouldn't want to push it larger than a 36T.

Originally Posted by wgscott View Post
It just arrived and I just put it on and it works fine on the stand, even with the old chain. I had to crank down the B-screw pretty much all the way, but it shifts though the gears fine. I can't use big-big, but I haven't put the new chain on (which will be longer). Everything else is smooth. I'll take it for a shake-down ride and post back if anything goes wrong.

Last edited by valueaudio; 07-27-17 at 04:52 PM.
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Old 07-27-17, 05:41 PM
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I'm getting a little bit of noise with the new chain, but I think it might be because I bought an XT chain, which is asymmetric, and it touches the POS FSA crank very slightly, but as far as the cassette and the derailleur go, it is fine. I noticed that this year's model of my wife's bike has this derailleur and an 11-34T cassette on it. (They also put a smaller crank on.) There was plenty of extra room on the B-screw on this bike, FWIW.
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Old 05-19-19, 11:13 AM
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Used a chain pin to shorten the mechanical stop since on my bike mounting a longer b-screw would not work : here a photo of what was done :

http://www.paulstephenborile.com/201...ar-derailleur/

It's working like a charm.
-Paul
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