To experts mechanics: FD Clamp or... on a Spesh Amira

Discuss light weight issues concerning road bikes & parts.
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LouisN
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Joined: Mon Feb 19, 2007 3:44 am
Location: Canada

by LouisN

My friend bought a Specialized Amira for his daughter. She's 11 yrs old, racing U12 category.

She has to use a 42T front Chainring for best ratio at 42 X 16 ( 6.00 meters ).

But the FD is a braze-on on the Amira, and at the lowest, is more than 8-10 mm over the big chainring, and the gear changes are a mess. The chain always drops over the big ring.

Any other options that wouldn't penalize the 6 meters ratio ?

I though putting a home-made "squared" 34.9 mm (I think we'll need bigger than that) clamp to the squared seat-tube below the braze-on till next year (she'll be U14 and then can use a 46T front chainring)...

What else ...?

Louis :)

by Weenie


system787
Posts: 138
Joined: Fri Mar 16, 2012 1:49 pm
Location: LA/OC, California

by system787

SRAM Braze-on FDs have two mounting positions. Or at least on the Red models.

Have you taken a look at those? Maybe it can get low enough for you

sigismond0
Posts: 236
Joined: Tue Feb 05, 2013 8:29 pm

by sigismond0

Sadly, that's probably not low enough. I have a Rival derailleur on the same bike as a 46t chainring, and it's about 4mm. It's functional, but not particularly smooth. I guess it's better than nothing at all though, so that's a reasonable fallback for OP.

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LouisN
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Joined: Mon Feb 19, 2007 3:44 am
Location: Canada

by LouisN

Yes, that's one of the "least worst" options for now. Using a 46T front chainring, but I'm shure that'll penalise her with the ratio, as 46-17 will probably be over 6.00 m (illegal) , but 46-18 will have her lose ground every pedal stroke...
I had an Excel file somewhere, but can't find it. probably 45T X 17 would bring her close to max 6.00 m .

Louis :)

crohnsy
Posts: 439
Joined: Mon Aug 16, 2010 6:43 pm
Location: Canada

by crohnsy

Hmm maybe possible to create a bracket the shape of the braze on mount with a hole for the derailleur bolt where you need it.then you can bolt the bracket to the braze on..

Now I know the u12 category is super competitive and serious business but how many more races does she have to be disadvantaged until next season?

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LouisN
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Joined: Mon Feb 19, 2007 3:44 am
Location: Canada

by LouisN

Good idea crohnsy. Brobably easy to to do as well :thumbup:
I know. But at the same time, when you're at your second and last season under a category, you want to perform at your best. Still 5 races to go, maybe 6...
Next year, she'll get the 46 X 16 ratio, the shifting "problem" will be resolved, but she'll be 1st year U14...struggling against the "big girls" again...

Louis :)

audiojan
Posts: 756
Joined: Fri Jan 27, 2006 1:38 pm
Location: Greater Pittsburgh

by audiojan

Rotor makes some shims that moves the derailleur back 6mm, and also a shim that is tapered 6mm/4mm (top-bottom). That should move the derailleur enough to make it shift ok.
"Suddenly the thought struck me; my floor is someone elses ceiling" - Nils Ferlin

by Weenie


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