front Derailleur bracket is too small to fit around cruzbike tube

Tarmac Terrorist

Active Member
I am hoping this is a common problem and someone has a solution. My front Derailleur came off a down tube that is 32.4mm but the cruzbike tube it has to go on is 35.6mm. Anyone got a cleaver solution?
 

Charles.Plager

Recumbent Quant
Hi,
I believe the "downtube"


Hi,

I believe the "downtube" on the conversion kit is 34.9 mm. They do sell derailleurs that work on that diameter. I don't know if you can find just the clamp to use the derailleur you already have or not....

Good luck,
Charles
 

BobD

Well-Known Member
Different clamp sizes are available

The FD come in different clamp sizes...... and also in a braze-on style (which is what the Silvio requires).
No worries, look for a FD that is the larger clamp size.

Clamp sizes are usually:
28.6 mm. 31.8. or 35 mm
I ran into the same problem when I took a FD off of my P-38. It was too small.

You can likely get a decent used FD at your LBS if they are the " collector type" that I like......vs the "boutique LBS"
Bob
 

Doug Burton

Zen MBB Master
Charles is correct here...

Our lower front tube is 34.9 mm nominal diameter; pretty common size for aluminum MTB and road bikes.

Two (well, three, maybe) options for configuration:

Top pull MTB derailleur: No need for the derailleur cable pulley included in the kit, but usually limited to 48 tooth large chainring,

Bottom pull MTB derailleur: Will need to use the cable pulley and has the same ring size limitation (although I've used MTB derailleurs "limited " to 48t on up to 54t chainrings - just need to know a couple of thins about cage alignement)

Bottom pull Road derailleur: Need to use the pulley or route the cable around the bottom bracket; usually good to 54t and can be made to work all the way to 60t.

These are generally not expensive parts, and as Charles said, a "non-boutique" (I like that term) LBS may have a good used one taken off during an upgrade:

http://www.amazon.com/SRAM-Dual-Pull-Front-Derailleur/dp/B000NNQJ6I/ref=sr_1_3?s=sporting-goods&ie=UTF8&qid=1354227763&sr=1-3&keywords=front+derailleur

http://www.amazon.com/SRAM-High-Clamp-28-6-Front-Derailleur/dp/B005541MIK/ref=sr_1_12?s=sporting-goods&ie=UTF8&qid=1354227763&sr=1-12&keywords=front+derailleur

http://www.amazon.com/SRAM-Apex-31-8-Front-Derailleur/dp/B003RLDICG/ref=sr_1_83?s=sporting-goods&ie=UTF8&qid=1354227968&sr=1-83&keywords=front+derailleur

Conversions will require a braze-on adapter clamp to use a braze-on derailleur; this is how we mount the derailleur on the Sofrider.

Cheers,

Doug
 

Charles.Plager

Recumbent Quant
Hi Doug,
I'm about to try and


Hi Doug,

I'm about to try and use a top pull MBB derailleur on a 50T chain ring. What advice do you have?

Thanks,
Charles
 

Tarmac Terrorist

Active Member
OK thanks, yes I can see lots

OK thanks, yes I can see lots of 35mm ones online for around $20 - many ask for a chain stay angle 63-66 or 66-69, I am assuming this is the angle of the down tube to chainstay? I can see I will have to setup with peddles etc adjust the downtube to my leg length and measure the angle.

As I have to buy a new one, I am going to "Do a Doug" and operate on the clamp with the grinder, I will let you know how I go.

BTW looks like I did not zero my digit vernier before measuring.

Question for John Tohurst and Doug (but any one can answer), is it possible to get spare / replacement parts? I need a C2, threaded dowell pin for steering tube clamp / down tube connector. I managed to crush mine in the vice tring to get the studs in (they simply would not screw in very far). I will use a bolt for now but would like to get the correct part. Also do you recomend lubricating the bushs and dowells for these and the chain stay to downtube connectors? ordinary grease or silicon?


 

Tarmac Terrorist

Active Member
OK The grinder did a great

OK The grinder did a great job and the old derailleur now fits, I have ordered a new one anyway. While in Bunnings getting a longer 5mm bolt I picked you some aluminium tubing that was perfect for the Dowell pin and made that while I was at it.OK The grinder did a great job and the old derailleur now fits, I have ordered a new one anyway. While in Bunings getting a longer 5mm bolt I picked you some alumiliul tubing that was perfect for the Dowell pin and made that while I was at it.

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