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Question on Moving a late 80s road bike to a compact 50/34 crank

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Question on Moving a late 80s road bike to a compact 50/34 crank

Old 06-22-20, 12:37 PM
  #1  
ryansu 
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Question on Moving a late 80s road bike to a compact 50/34 crank

I am refurbing a 1989 Specialized Allez and while I like it in stock 53/39 double form and have I've lost over 40 lbs recently making hill climbing a bit easier - the reality is I am a mid 50s dude in hilly Seattle. A compact double would make a lot of sense and the bike is going to be torn down anyway, so now is a good time to make the change and make the bike more versatile (i.e easier on the hills). I can get an FSA Vero 50/34 (square taper) for about $50 and I already have a 110mm cartridge square taper BB. My concerns are as follows:
  • New crank affecting chainline and therefore the indexed shifting of the Suntour GPX gruppo
  • Stock GPX FD being able to handle a 16 tooth drop in chain rings (I can get a new FD but it would be great if the stock one worked)
  • 9 speed crank and 7 speed drive train, don't think this will be a problem but.. The wheels are Stock Wolber and the gears are a 7 speed FW and I don't really want to change that out.

Just wondering for anyone who has done this if they have suggestions, cautions, things I haven't considered. Thank you


Allez as-is
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Old 06-22-20, 12:39 PM
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you will have no problems whatsoever. swap in, shorten chain, ride.
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Old 06-22-20, 12:45 PM
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Chain and new crank shouldnt be an issue. Chainline shouldnt be off more than 2mm if u have right bb.
50 to 14 gives u about 96 inches. It would be tall enough for me. 50 to 13 is only higher if thats what u have. My only question would be if you might not consider a better used crank. Having said that what u propose sounds pretty good.

Oh yeah, the fd will probably handle it fine.
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Old 06-22-20, 12:54 PM
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As an alternative, you could use a Wolf Tooth Roadlink. Tbis as will extend the derailleur mounting point down to clear a larger cog. I have thin a Dura Ace 7800 drive train with a 53 x 39 crank. Put an inexpensive 11-36 cassette on, it took all of ten minutes to install. ow a climb anything!
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Old 06-22-20, 01:00 PM
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You should be fine. Chainline specs have not changed. It's worth paying some attention to making sure it stays correct. If have the correct BB spindle length, should be an easy swap. https://www.sheldonbrown.com/chainline.html

Don't forget to lower and re adjust your FD..

I should mention that it is usually easier, cheaper and more effective to swap your freewheel or cluster and RD, rather than change the cranks. However in your case finding a compatible Suntour indexing derailleur etc at this point in time could be challenging.
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Old 06-22-20, 01:05 PM
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Originally Posted by Bikejock200M View Post
As an alternative, you could use a Wolf Tooth Roadlink. Tbis as will extend the derailleur mounting point down to clear a larger cog.
Oh yeah, forgot about these newfangled things. That's another option for sure. Suntour ultra freewheel should be findable or makeable. Looks like the current one is 13-21, which is pretty brutal if you're not a racer. Even a 13-28 would provide a much lower gear than a compact 50/34 crank would.
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Old 06-22-20, 02:46 PM
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+1

What he said.
Originally Posted by jetboy View Post
you will have no problems whatsoever. swap in, shorten chain, ride.
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Old 06-22-20, 02:48 PM
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Originally Posted by Bikejock200M View Post
As an alternative, you could use a Wolf Tooth Roadlink.
Do both, climb comfortably.
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Old 06-22-20, 04:35 PM
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Originally Posted by Salamandrine View Post
Oh yeah, forgot about these newfangled things. That's another option for sure. Suntour ultra freewheel should be findable or makeable. Looks like the current one is 13-21, which is pretty brutal if you're not a racer. Even a 13-28 would provide a much lower gear than a compact 50/34 crank would.
its a SunRace 13-25, I have been told people get the GPX RD to work with a 28t big cog but I tired and couldn't.
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Old 06-22-20, 04:42 PM
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Thanks so much to all of you for the feed back. I have ordered the FSA Vero and if it all works out and I love it, I will save my pennies for something more vintage looking to put on the Allez like a Sugino XD2 and swap the Vero to something I am selling.
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Old 06-22-20, 05:34 PM
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that might not look bad on it actually- still a pretty classic looking crankset--
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Old 06-22-20, 05:57 PM
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Should work fine. I managed to find one of these FSA Omega compact cranks with silver rings. I replaced the Dura Ace 7800 crank I was running on my Raleigh Competition. Shifts like a champ with DA7800 10spd group. The FSA’s q-factor is wider than the DA and noticeable at first. If you ride 170 arms, I’d opt for the Shimano RS 500 in the bottom pic. Available in silver or black and one of the classier looking modern cranksets IMO.




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Old 06-22-20, 06:39 PM
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Dang, these cranks go for cheeeeeeap. I'm pretty tempted.

https://www.ebay.com/itm/Shimano-RS-...4383.l4275.c10
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Old 06-28-20, 07:49 PM
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The FSA Vero compact crank is Mounted! now I just need to finish the rebuild and see how it works on the road

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Old 07-11-20, 11:27 AM
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The compact cranks works great, there are some iffy shifts in the 21 and 23t cogs but that is a result of the GPX shifters and derailleurs paired with a new SunRace 7 speed FW. The Vero Compact goes smoothly between the 50 and 34 chainrings. To make this a real climber I would need lower cogs out back but that would require a different RD which would mean the shifters too would need replacing (from what I have read) so for now this is the blasting on the flats and rollers bike which it does quite well



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Old 07-11-20, 11:58 AM
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Looks nice. SHould work great.

I was using a Stronglight Impact crankset (technically 9/10 speed) with 8 speed Campy (13-26 rear) but recently switched it over to 10 speed and a 13-29. I've got another Stronglight on order to do a new build with 8 speed.

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Old 07-11-20, 10:05 PM
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I had a 50 - 34 compact double put on my 1980s Miele Uno LS and it worked just like a normal double except it had lower gearing now.



Cheers
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Old 07-12-20, 03:57 AM
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Originally Posted by Miele Man View Post
I had a 50 - 34 compact double ... and it worked just like a normal double.
Sure helps to use a mid- or (in your case) long-cage rd.

A short cage, like Nuovo Record or Sprint rd can't easily support such a wide gap in required chain length between the two rings.
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Old 07-12-20, 04:23 AM
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Originally Posted by ryansu View Post
The compact cranks works great, there are some iffy shifts in the 21 and 23t cogs but that is a result of the GPX shifters and derailleurs paired with a new SunRace 7 speed FW. The Vero Compact goes smoothly between the 50 and 34 chainrings. To make this a real climber I would need lower cogs out back but that would require a different RD which would mean the shifters too would need replacing (from what I have ready) so for now this is the blasting on the flats and rollers bike which it does quite well


Looks nice!

Since you would like to stay with the SunTour Accushift Indexing, and you are having some imprecision in a few combinations my suggestion would be to find a used SunTour Winnner Pro (the one that takes the 4 prong removal tool) or “AP” freewheel. You might have to check back frequently on eBay but eventually one will present itself at a good price. The SunTour indexing is asymmetric with the lower 3 cogs on a 7 speed being spaced 0.1 mm tighter (IIRC). This slight asymmetry in spacing makes dialing in clean indexing in all 7 gears not spot on with other brands of free wheels. I would have thought the GPX would handle a 28 tooth cog as well.
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Old 07-12-20, 08:22 AM
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Originally Posted by masi61 View Post
Looks nice!

Since you would like to stay with the SunTour Accushift Indexing, and you are having some imprecision in a few combinations my suggestion would be to find a used SunTour Winnner Pro (the one that takes the 4 prong removal tool) or “AP” freewheel. You might have to check back frequently on eBay but eventually one will present itself at a good price. The SunTour indexing is asymmetric with the lower 3 cogs on a 7 speed being spaced 0.1 mm tighter (IIRC). This slight asymmetry in spacing makes dialing in clean indexing in all 7 gears not spot on with other brands of free wheels. I would have thought the GPX would handle a 28 tooth cog as well.
Thanks for the compliment and suggestions. I did a cursory look at ebay and most of the 7 speed Suntour offerings were in the $50 and up, sometimes way up category and/or were corncobs but I might have to do periodic checks. I have heard from others that a 28t cog would work with this set up but when I tried I could not manage it. Another suggestion I have seen is a wolfstooth on the RD hanger for using larger cogs on short cage RD. For now I am going to ride it and smile and maybe in the winter I will tinker some more.
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Old 07-12-20, 09:00 AM
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Congrats. Did you lower the front derailleur?
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Old 07-12-20, 10:06 AM
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Originally Posted by ctmullins View Post
Congrats. Did you lower the front derailleur?
Hmm hadn't thought about I just set it for the 50t ring but since the old ring was a 53 I probably did - This was a total tear down so I put the compact on when I was reassembling the bike. The nice thing is that the stock GPX FD and RD handle the 16 tooth drop of the 50/34 combo just fine.
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