Classic & Vintage - Single Chainring Geared Bikes -- any advice?

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RFC
05-11-11, 05:20 PM
I'm thinking about modifying my now SS Volpe into a geared bike with a single chainring. Do I need to worry about a chain guard of the big ring?

Thanks

RFC

auchencrow
05-11-11, 05:30 PM
I am not clear on your question - Do you mean the big cog?

If so, I would think you may have the raise the chain guard at the rear a little, in the event that you get chain slap due to it's closer proximity when in low gear.
ftwelder
05-11-11, 06:12 PM
I'm thinking about modifying my now SS Volpe into a geared bike with a single chainring. Do I need to worry about a chain guard of the big ring?

Thanks

RFC

I have an old Carlton Corsair that is a five speed from the factory. I have noticed that I am able to sprint and pedal over bumps but there is a tendency for the chain to derail going from a fast cadence to "stopped" or slowing too fast. I have found it generally better to keep a very low pedaling cadence with a 5-speed .

Puget Pounder
05-11-11, 06:15 PM
If you're talking about a guard to prevent dropping when you cross chain then I would suggest you get one. I built a bike like that and it dropped frequently over bumps or a quickshift throughout the range even with the chainline in the dead center of the cluster. I used a front derailleur to keep the chain and it worked perfectly. Some people get away without it though.

But I am not sure that's what you're asking...
Grand Bois
05-11-11, 06:24 PM
It's clear enough to me. Try it and see if the chain drops. If so, there are a few fixes, the simplest of which is an immobilized front derailer.

I'm not sure if it made a difference that I used a Simplex derailer with a sprung top pivot, but seemed to keep a lot of tension on the chain. I never had the chain drop. Peugeot built a lot of five speeds with Simplex derailers.

http://inlinethumb56.webshots.com/47159/2065964610068014369S600x600Q85.jpg (http://rides.webshots.com/photo/2065964610068014369FUbMOl)
http://inlinethumb10.webshots.com/1673/1471891884068014369S600x600Q85.jpg (http://news.webshots.com/photo/1471891884068014369tHMFRC)
atmdad
05-11-11, 06:32 PM
Try it and see if the chain drops. If so, there are a few fixes, the simplest of which is an immobilized front derailer.

Exactly. I have my beater/grocery getter 5 speed with a 50 up front and 14-28 rear with no problems. My daughters bike, very similar but with a 44 I believe up front and she would drop the chain. A fixed front derailer up front solved it.
mazdaspeed
05-11-11, 06:46 PM
I've had good luck with 39x8
formicaman
05-11-11, 07:03 PM
There's always internal hubs.
Henry III
05-11-11, 07:48 PM
I was thinking of doing the same thing with my World Sport frame for a CX build. I have a pair of NR cranks but only a 42T chainring for it. Then I'd run a 5 or 6 speed freewheel in the rear. I was wondering if I'd have problems with dropping the chain also. Guess I'll just have to find out.
David Newton
05-11-11, 08:00 PM
I am contemplating doing the same thing, I'll have a 42 x 14-28 fw. I suspect chain length and RD spring tension will be key factors.
I imagine the shortest chain that will do the job is best.
southpawboston
05-11-11, 08:11 PM
I have a 45 x 13-30. I've never had the chain drop. I supposed if there's not enough chain tension, it could be an issue.
Velognome
05-11-11, 08:33 PM
FWI- I rode a UO9 for years with only a RD, making it a 5 spd. Kept the Chain on the large ring and never had a problem with the chain drop or with cross over.
PDXaero
05-11-11, 08:43 PM
FWI- I rode a UO9 for years with only a RD, making it a 5 spd. Kept the Chain on the large ring and never had a problem with the chain drop or with cross over.

Same here. A 5 speed uo-09 because the front deraillieur was broken when I got it. My first road bike. *daydreaming*
RFC
05-11-11, 11:07 PM
All good advice. Thanks. Seems like chain/RD tension may be a clue. In other words, "make that derailleur scream!" :D
Velognome
05-12-11, 06:26 AM
http://www.bikeforums.net/showthread.php/images/misc/quote_icon.png Originally Posted by Velognome http://www.bikeforums.net/showthread.php/images/buttons/viewpost-right.png (http://www.bikeforums.net/showthread.php/showthread.php?p=12630545#post12630545)
FWI- I rode a UO9 for years with only a RD, making it a 5 spd. Kept the Chain on the large ring and never had a problem with the chain drop or with cross over.



Same here. A 5 speed uo-09 because the front deraillieur was broken when I got it. My first road bike. *daydreaming*




All good advice. Thanks. Seems like chain/RD tension may be a clue. In other words, "make that derailleur scream!" http://www.bikeforums.net/showthread.php/images/smilies/biggrin.gif

Or speak French