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Specialized hotrock 20 problems with 7 speed conversion

1488 Views 6 Replies 4 Participants Last post by IstominIS, Dec 20, 2021

IstominIS

Discussion Starter · Dec 19, 2021

Good evening, All.

I need some help.
I wanted to convert my daughter’s Specialized Hotrock 20 bike to 7 speed and change the shifter for trigger type to make it easier for my 5 year old to change the gears but I face a problem.

I have installed Alivio 7 speed rapid fire shifter, Altus 7 speed rear derailleur with short cage and big bottom jockey wheel and 7 speed sunrace freewheel with 34t cog. New chain was installed.

Unfortunately, when I started mounting rear derailleur and testing, I have noticed that the chain line is too skew when the chain is on the small cog. This causes chain to rub against the big bottom jockey wheel as chain doesn’t go on it nicely.

I had damaged derailleur hanger that I will replace tomorrow. After that the only old parts left is front chain ring (don’t think it is the cause) and the bottom bracket. I’m thinking to move bottom bracket somehow or put some spacers. I could not take it out yesterday, will try tomorrow again with the right tools.

Have anybody had the same issues? How did you solve them.

Thanks for help.

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Mountainfrog

· #2 · Dec 19, 2021

Replace the bent hanger first. Adjust your high limit screw. Refer to this video.

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IstominIS

Discussion Starter · #3 · Dec 19, 2021

Mountainfrog said:
Replace the bent hanger first. Adjust your high limit screw. Refer to this video.

Thanks. I have tried the adjustments. It is not the limit screw. I'll try again tomorrow with the new hanger and let you know. But I clearly see that there is a big side position difference between the jockey wheel and the front chain ring. Hope hanger will resolve the problem.

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Mountainfrog

· #4 · Dec 19, 2021

IstominIS said:
Thanks. I have tried the adjustments. It is not the limit screw. I'll try again tomorrow with the new hanger and let you know. But I clearly see that there is a big side position difference between the jockey wheel and the front chain ring. Hope hanger will resolve the problem.

It will make a difference, a bent hanger is the worst cause of shifting woes. 😝

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slapheadmofo

· #5 · Dec 20, 2021

IstominIS said:
I'll try again tomorrow with the new hanger and let you know. But I clearly see that there is a big side position difference between the jockey wheel and the front chain ring. Hope hanger will resolve the problem.

Unless the jockey wheel is way out of alignment with the cog, doesn't sound likely that the hanger is going to do much.

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BicyclesOnMain

· #6 · Dec 20, 2021

Every multi speed kid's bikes I've ever worked on had a bent hanger. Sounds like it is bent inwards towards the rear of the bike.

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IstominIS

Discussion Starter · #7 · Dec 20, 2021

BicyclesOnMain said:
Every multi speed kid's bikes I've ever worked on had a bent hanger. Sounds like it is bent inwards towards the rear of the bike.

Hi All

I have changed the hanger and IT WORKED 100%! I was not hoping for this. Now shifting is smooth and soundless. And finally my kid can change the gears both ways

She was so excited and wanted to try that we have made 3 km in the night forest with -1 C outside next to the house.
Now I can relax. Thanks everybody who advised on solution.
Have a nice evening.

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