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I've just change the freewheel for a 34T and I also changed my rear derailleur for a Tourney 7sp (i run friction shifters).

I would like to have a bit more distance between the cogs and the derailleur. But I cannot. What am I doing wrong? Or are there any trix?

34T freewheel with Tourney derailleur Closeup B tension screw maxed out

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    nice depth of field in the 2nd pic (macro photo?)
    – amonk
    Jun 28, 2017 at 16:13
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    @amonk its a 25f0.95 on micro four thirds.
    – Ola
    Jun 28, 2017 at 17:58
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    I've been riding it for a while now and it works fine.
    – Ola
    Feb 20, 2018 at 18:19

5 Answers 5

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That's just what the combination of the 34T rear cog and Tourney derailleur looks like. Here's mine, using the 38T chainring:

enter image description here

Using the 28T chainring doesn't move the top derailleur pulley any farther from the cog, so using a longer chain won't make any difference.

It doesn't seem to cause any problems for me, though I don't use the 34T rear cog very often: it's too much of a jump in gear ratios from the next one down, which is a 24T.

However, I don't have the same model of Tourney derailleur as you. Your derailleur looks like the RD-A070 and Shimano's compatibility listings indicate that this is only compatible with freewheels whose largest cog is a 28T.

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    I myself really think the 34T is a great feature. When it's a harder hill it's nice to be able to get really low geared. Especially with a kid on the back and some picnic on the rack :)
    – Ola
    Jun 28, 2017 at 11:17
  • I've been thinking of going with 34T myself. I currently have front 48-38-28 and rear 24-...-14, which is fine on flats but I live on hills, and (I see now) I really should have had mountain gearing from day one, which mine is not.
    – compton
    Jun 28, 2017 at 13:56
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    @compton It depends on how you use the gears. If you regularly find yourself needing a gear lower than 28/24 then go for it. In my area, 38/24 is fine for most of the hills and, when it isn't, I'd much rather drop down to the small chainring at the front and use 28/14-24. The problem comes when I think I can tackle a hill on my middle chainring but misjudge it slightly. If I can't get up at 38/24, my only options are to use the front derailleur under load or change to 38/34, which is a huge jump in ratio. I'd much prefer to be able to go to something like 38/26 or 38/28 instead.
    – David Richerby
    Jun 28, 2017 at 14:15
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    @compton Do you mean small chainring and big rear? Small chainring and small rear gives you the same sort of gear ratios as middle chainring and middle rear: 28/14 is roughly the same as 38/18 or 38/20 (it's actually 38/19).
    – David Richerby
    Jun 28, 2017 at 22:21
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    @DavidRicherby And yesterday was my day ...
    – compton
    Jun 29, 2017 at 17:07
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It's not completely solved yet but I think it will work now. I tightened the b tension screw as much as I could and now it doesn't touch the 34t cogs any more. I'll ride with it a month to see if it worked itself out or not.

Thanks for all help and good suggestions!

Update after 2 weeks: It seems to work fine.

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Try tweaking the B tension screw. It is very likely the big shiny silver combo pilips/flathead in your third picture.

As you tighten the screw it should increase pressure on the internal spring. making the upper jockey wheel further forward.

Slackening the screw a bit should relax the spring and allow the chain to pull it toward the back, and therefore further from the big cog.

Get your bike up on a stand or hang it from some ropes and give it a try.

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You might be able to get some more clearance by replacing the top jockey wheel with a smaller one.

Yours appears to be a 14 tooth in the picture. Jockey wheels are available from 10 tooth to 15 tooth.

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    I've got this exact problem on my folder, which is a 32 tooth big gear. Turns out its possible for the top jockey wheel to clip over to the wheel side of the large cog and stay there until I get off and help it shift back down by hand. Not ideal!
    – Criggie ♦
    Jun 28, 2017 at 10:22
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    Thanks! To replace the top jockey wheel is a smart idea! I'll try that first. Think I have some wheels lying around :)
    – Ola
    Jun 28, 2017 at 10:58
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    I tried to change the jockey wheel but strangely it didn't help.
    – Ola
    Jun 30, 2017 at 16:23
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Adding an adapter called "hanger extender" "extended link" and many times named by the product "roadlink". The derailleur position will change having more space and it will allow to reach bigger cog rings; with more tooth than supported in specs (mostly 28 or 30T)

As your tourney is long cage it will deal with differences between the min am max cog size.

Whereas a short/medium cage will add complexity.

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    Its worth adding the downsides - that the rear derailleur hangs lower, and has lower tooth engagement with the smaller cogs. Everything's a trade-off
    – Criggie ♦
    Aug 9, 2022 at 23:44

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