34 tooth inner ring for older crankset that has 52/40?
11-13-17, 12:59 AM
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34 tooth inner ring for older crankset that has 52/40?
I have a vintage bike that has a 6 speed 14-28 freewheel and a 52/40 chainring set. The cranks are Sugino MP 110 with a 5 bolt 110mm BCD. Even with the lowest ratio, climbing can be tough (27" wheels don't help either) and so I was wondering if I could easily just swap the inner chainring with 34 tooth one? This method seems much simpler to me than getting a wider range freewheel with the amount of work required for it to function. If you can find a few links with this type of chainring I'd really appreciate it.
11-13-17, 02:55 AM
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Vuelta has 110 BCD 34T chainrings. I recently swapped out my road bike's 42T small chainring for a Vuelta SE Plus 39T.
Helps a bit with climbs on the original 13-24 7-speed freewheel. I tried a 13-25 freewheel but didn't like the spacing with the new 39T chainring -- too much double shifting to find the sweet spot, and I was losing momentum going into climbs. I already struggle to keep up with a local group and couldn't afford to fall off the back and open a gap going into climbs, because I can't sprint fast enough to close the gaps. Spacing is fine with the 52/39 chainring and 13-24 freewheel. (Yeah, I'm at a self imposed disadvantage trying to ride a 1980s 7-speed steel road bike with downtube shifters to keep pace with folks riding carbon fiber bikes and brifters.)
Check the Sheldon Brown or other site with a calculator to estimate gear inches/ratios for any swaps to chainrings or freewheels to be sure the specs suit you. But if you're touring or commuting at a modest pace and not training hard or trying to keep up with a fast group ride, the gear spacing won't be as important.
Good quality, works fine, shifts as well as the original. Only problem was a few chain drops on downshifting the first couple of rides, but tweaking the front derailleur adjustments fixed that.
I paid only $7 for the Vuelta, which was heavily discounted via an Amazon Warehouse sale that advertised it as new but scuffed -- actually only the cardboard packaging was scuffed, but the chainring itself was perfect. I'm satisfied enough that I'd pay the regular price next time if I needed another chainring.
Helps a bit with climbs on the original 13-24 7-speed freewheel. I tried a 13-25 freewheel but didn't like the spacing with the new 39T chainring -- too much double shifting to find the sweet spot, and I was losing momentum going into climbs. I already struggle to keep up with a local group and couldn't afford to fall off the back and open a gap going into climbs, because I can't sprint fast enough to close the gaps. Spacing is fine with the 52/39 chainring and 13-24 freewheel. (Yeah, I'm at a self imposed disadvantage trying to ride a 1980s 7-speed steel road bike with downtube shifters to keep pace with folks riding carbon fiber bikes and brifters.)
Check the Sheldon Brown or other site with a calculator to estimate gear inches/ratios for any swaps to chainrings or freewheels to be sure the specs suit you. But if you're touring or commuting at a modest pace and not training hard or trying to keep up with a fast group ride, the gear spacing won't be as important.
Good quality, works fine, shifts as well as the original. Only problem was a few chain drops on downshifting the first couple of rides, but tweaking the front derailleur adjustments fixed that.
I paid only $7 for the Vuelta, which was heavily discounted via an Amazon Warehouse sale that advertised it as new but scuffed -- actually only the cardboard packaging was scuffed, but the chainring itself was perfect. I'm satisfied enough that I'd pay the regular price next time if I needed another chainring.
11-13-17, 03:36 AM
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You can attach any 34T 5-bolt 110BCD chainring to your cranks. You can even still get one from Sugino (Sugino Standard Chainring). However...
You'll also need to make sure that your rear derailleur has enough wrap to take up the extra difference. (28-14) + (52-34) = 32, which is more wrap than short-cage vintage derailleurs tend to have. If your rear derailleur is being pushed too far, you could look for vintage long-cage derailleurs, like the SunTour GT models... but the easy solution is to just Grant Peterson it and throw a cheap modern MTB derailleur onto the bike, like the Acera or Alivio or Altus ones.
A vintage double will likely shift dubiously if you have an 18-tooth difference between chainrings. Even modern setups rarely go bigger than a 16-tooth difference between two chainrings, and modern tooth and derailleur profiling makes them far better at big jumps.
Going 3x can solve that issue, but you may need to change your bottom bracket spindle length.
You'll also need to make sure that your rear derailleur has enough wrap to take up the extra difference. (28-14) + (52-34) = 32, which is more wrap than short-cage vintage derailleurs tend to have. If your rear derailleur is being pushed too far, you could look for vintage long-cage derailleurs, like the SunTour GT models... but the easy solution is to just Grant Peterson it and throw a cheap modern MTB derailleur onto the bike, like the Acera or Alivio or Altus ones.
A vintage double will likely shift dubiously if you have an 18-tooth difference between chainrings. Even modern setups rarely go bigger than a 16-tooth difference between two chainrings, and modern tooth and derailleur profiling makes them far better at big jumps.
Going 3x can solve that issue, but you may need to change your bottom bracket spindle length.
Last edited by HTupolev; 11-13-17 at 03:51 AM.
11-13-17, 10:21 AM
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If the 40T inner ring is too much, what about the 52T? Old 110BCD Sugino cranks make for great vintage compacts if you go ahead and swap both rings:
A 48/34 set like above should work well with your existing derailleurs if that's a concern/issue.
A 48/34 set like above should work well with your existing derailleurs if that's a concern/issue.
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11-13-17, 10:25 AM
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I was wondering if I could easily just swap the inner chainring with 34 tooth one?
Maybe in another dimension you will get physics that allow something to be fitted outside of itself, but all you can do in this dimension is 33t. [TA, many $$]
and for long wear Surly [QBP] produces a stainless steel chainring, 110 bcd from 34t upward..
a tripleizer chain ring becomes the middle of a triple, with its own smaller bolt circle, 74 , so then a 24t capable..
you could buy a 14~34T freewheel (+ a new chain)..
you could put a 50t outer... the 50 - 34t combo is very popular nowadays.
....
Last edited by fietsbob; 11-13-17 at 10:36 AM.
11-13-17, 02:24 PM
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I doubt you'll like it. Search for 50/34 compact crank threads. Whatever complaints those folks had, a 52/34 is going to be worse.
Honestly, I'm thinking a 14/34 freewheel with a mountain bike rear derailleur is going to be more likely to give you the hill climb gear that you need with the ride-ability that you want.
Honestly, I'm thinking a 14/34 freewheel with a mountain bike rear derailleur is going to be more likely to give you the hill climb gear that you need with the ride-ability that you want.
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11-13-17, 02:29 PM
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Key is don't expect to get out of the smallest chainring until you are headed down hill a bit.
11-14-17, 01:38 AM
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I doubt you'll like it. Search for 50/34 compact crank threads. Whatever complaints those folks had, a 52/34 is going to be worse.
Honestly, I'm thinking a 14/34 freewheel with a mountain bike rear derailleur is going to be more likely to give you the hill climb gear that you need with the ride-ability that you want.
Honestly, I'm thinking a 14/34 freewheel with a mountain bike rear derailleur is going to be more likely to give you the hill climb gear that you need with the ride-ability that you want.
The only other alternative to the funky gearing (that I can think of) would be to spread the chain stays to 130mm and fit a modern wheel with 8-10 gears. Not sure if that would do it but right now I'm not satisfied with it.
