# HELP: no "B-tension" screw on Shimano Tourney rear derailluer (RD-FT30) ?



## PiroChu (Apr 8, 2004)

Hi folks,

So I recently picked up an used '09/'10 Hotrock for my daughter, and it has a Shimano Tourney rear derailluer (RD-FT30).

When in the lightest/largest cassette cog, the upper pulley hits it, being too close to each other. So, I thought to adjust the B-tension screw as usual, only to find that there's no such on this rear derailluer. (There're only the usual high- and low-range adjuster screws.)

So, without the B-tension screw, how do I make this adjustment with this rear derailluer? 

Shimano tech docs: Tourney

Thanks for your info in advance,
- PiroChu


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## Shayne (Jan 14, 2004)

Based on that tech-doc the b-tension screw is in the body of the derailleur right by the cable adjuster barrel. Part #4 on those diagrams.


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## PiroChu (Apr 8, 2004)

Shayne said:


> Part #4 on those diagrams.


Sorry, my bad, I should've specified (just edited/specified in my original title/post now.)

It's RD-FT30 of the Tourney line, and that model doesn't have the "part#4" (B-tension); hence my question.

http://techdocs.shimano.com/media/t...I_5VF0A/SI-5VF0A-En_v1_m56577569830607125.pdf


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## Rakuman (Oct 30, 2004)

PiroChu said:


> Sorry, my bad, I should've specified (just edited/specified in my original title/post now.)
> 
> It's RD-FT30 of the Tourney line, and that model doesn't have the "part#4" (B-tension); hence my question.
> 
> http://techdocs.shimano.com/media/t...I_5VF0A/SI-5VF0A-En_v1_m56577569830607125.pdf


I chose to upgrade that derailleur for this for 16 bucks problem solved
Shimano Tourney TX55 6 7 Speed Rear Derailleur Direct Attach | eBay


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## PiroChu (Apr 8, 2004)

Figured it out...

So, the B-tension for RD-FT30 is simply "adjusted" by the length of the last piece of cable housing ("X + 10mm" per PDF manual), LOL.

It was too long before. Anyway, upon re-adjustment, it works fine now, thanks.

{EDIT}
And here's a pic (taken on 7/11/'13)...


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## evandy (Oct 3, 2012)

Huh? I admit there's a ton I don't know about bikes, but how does the length of housing change anything? I can see how the cable tension (relative length of cable housing to the cable) might change things, but you can adjust that by loosening the set screw and tightening or loosening the inner cable.

Can someone tell me what I'm missing here?


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## PiroChu (Apr 8, 2004)

evandy said:


> I can see how the cable tension ... might change things


Basically, think of "B-tension" as an "angle" (rather than "tension") adjustment.

I'm not the best to explain this, so here's a quote from Sheldon's...


> Most derailers have an angle adjustment screw (Shimano calls it "B-tension adjustment"). This adjusts the tension of the upper ("b") spring of the parallelogram, and thus the height of the jockey pulley. The looser this screw is, the closer the jockey pulley will be to the cluster.


Derailer Adjustment by Sheldon Brown
Park Tool Co. » ParkTool Blog » Rear Derailler Adjustments (derailleur)

So, normally the screw holds the derailluer angle, which is not affected by the length of the last piece of cable housing. (eg. If too long, it'll just flare out, while the screw still keeps in the same angle.) However, in the case of this cheapo rear derailluer, there's no screw to hold it to an set angle, so the length of the last-segment housing has to (sorta) "functionally act" as such.

Again, probably not best describing it, but anyways it works now. :thumbsup:
- PiroChu


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## evandy (Oct 3, 2012)

Ok. That's weird and worrysome, but makes some sense at least.


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## Tobyedward (Sep 9, 2010)

PiroChu said:


> Figured it out...
> 
> So, the B-tension for RD-FT30 is simply "adjusted" by the length of the last piece of cable housing ("X + 10mm" per PDF manual), LOL.
> 
> It was too long before. Anyway, upon re-adjustment, it works fine now, thanks.


I've got exactly the same issue with the B-tension on a Shimano Tourney so I'm really pleased to have found such a recent thread on it. Can you explain how to measure the length of cable housing required, or point me in the direction of a manual?

Would I be right in thinking that the cable housing needs to be shortened?

Thanks


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## PiroChu (Apr 8, 2004)

Tobyedward said:


> Can you explain how to measure the length of cable housing required, or point me in the direction of a manual? Would I be right in thinking that the cable housing needs to be shortened?


The Shimano online PDF manual (links in above posts) says the following:



> Cable securing and stroke adjustment
> • If routing the casing upward:
> Add 10 mm to the length of the outer casing
> from the end that is inserted into the outer
> ...


So, the measuring method is slightly different, depending on whether your rearl-derailluer cable runs along the seatstay ("_upward_") or the chainstay ("_downward_").

My daughter's '09 Hotrock runs it along the seatstay, so I followed the "(distance) + 10mm" formula, and now it works fine. The original piece was too long, and I had to cut it down by about an inch or so. (I actually kept a tad extra, about "distance + 15mm-ish".)

To measure this "distance" portion of the "(distance) + 10mm" formula with the seatstay route, make sure to note the 'angle/position' of the rear-derailluer when it's in the largest cassette cog, then measure it from the last cable stop on the frame to the first cable entrance on rear derailleur.)

Regardless of whichever cable routing, if the last piece of cable housing is too long, the upper pulley will hit the largest cassette cog. If too short, I'd imagine that they'll be too far apart (also not desirable). They say that the "width-of-a-pencil apart" cog-to-pulley is appropriate.

Good luck,
- PiroChu


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## Tobyedward (Sep 9, 2010)

Thanks PiroChu - that's really helpful. Mine runs along the chainstay so I'll go for the smooth arc as described, but as the housing is currently too long, I'll probably cut it down gradually and test as I go to avoid going too short.

Thanks again.


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## Neil1210 (Nov 3, 2021)

evandy said:


> Ok. That's weird and worrysome, but makes some sense at least.





Tobyedward said:


> Thanks PiroChu - that's really helpful. Mine runs along the chainstay so I'll go for the smooth arc as described, but as the housing is currently too long, I'll probably cut it down gradually and test as I go to avoid going too short.
> 
> Thanks again.


Hi hope your all still out there. But a stupid question. I have the same problem. Sorry I don't know the bike terms but the derailleur is rubbing in gear 1 the biggest gear and no B screw. So do I just need to shorten the black gear wire housing to solve this ? Seems a very random thing to do ?
Thanks Neil


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## 127.0.0.1 (Nov 19, 2013)

evandy said:


> Huh? I admit there's a ton I don't know about bikes, but how does the length of housing change anything? I can see how the cable tension (relative length of cable housing to the cable) might change things, but you can adjust that by loosening the set screw and tightening or loosening the inner cable.
> 
> Can someone tell me what I'm missing here?


this der has no B screw, it is literally adjusted by housing length 

see the manual


https://si.shimano.com/api/publish/storage/pdf/en/si/6KP0A/SI-6KP0A-001-ENG.pdf


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## Neil1210 (Nov 3, 2021)

Sorry still lost with it. So do I need to make the cable shorter or get a new section and make it longer. And is it the last section on the back of the bike. I'm just trying to fix a 6 year old handme down bike. So far I have just set it to 5 gears via the limit screws


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## J.B. Weld (Aug 13, 2012)

127.0.0.1 said:


> this der has no B screw, it is literally adjusted by housing length
> 
> see the manual
> 
> ...




It literally isn't. The doc you linked shows a derailleur with a standard b-screw. No derailleur I've ever seen uses cable length for b adjustment.


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## J.B. Weld (Aug 13, 2012)

Neil1210 said:


> Hi hope your all still out there. But a stupid question. I have the same problem. Sorry I don't know the bike terms but the derailleur is rubbing in gear 1 the biggest gear and no B screw. So do I just need to shorten the black gear wire housing to solve this ? Seems a very random thing to do ?
> Thanks Neil



Is the derailleur compatible with the amount of teeth your cassette has?


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## 127.0.0.1 (Nov 19, 2013)

J.B. Weld said:


> It literally isn't. The doc you linked shows a derailleur with a standard b-screw. No derailleur I've ever seen uses cable length for b adjustment.



all the ders here have B screws, *except the RD-FT30*
here you use....only housing, cuz there is nothing else to use
OR...it just doesn't need it...but there be no *B* on it


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## Neil1210 (Nov 3, 2021)

OK so I tried a longer housing and shorter housing and no luck. I went as short as I could little by little but still the top cog hits the derailleur. I could not really make it very long as there was not enough cable as it had been cut to short. I have ordered new housing and cable as it frayed. The thing just does not like me.


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## Neil1210 (Nov 3, 2021)

OK so I think I have now cracked it. Buy my god do you need to cut alot of housing. So I had to prity much cut the housing in half, but now no rubbing and a good gap in 1st gear.


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