Bicycle Mechanics - Triple crank for old 10-speed?
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05-14-09, 05:47 AM
Can I swap in a triple crank on an old '70s era 10 speed bike? The bike is a Swchinn LeTour and the crank is not a one-piece unit.
The bike is fine but I would like some lower gears for the hills on my commute.
05-14-09, 06:18 AM
I've done this...actually on a '70s bike.....yikes, back in the '70s actually. I think it was a Peugeot PX-10. Anyway, you will likely need a longer BB axle and be sure your derrailer has enough travel for the triple chainrings. Good luck!
05-14-09, 09:47 AM
Go for it... The BB shell on that bike is set up for a standard English BB, so any compatible triple BB/crank combo should be a suitable candidate.
I haven't done it myself, but I have gone compact double in a similar situation.
05-14-09, 10:00 AM
You'll want to put the recommended BB with the new crank. I recently did an '88 Schwinn but used a compact double (34/50) crank. That gives plenty of low for the hills. One problem you might have is getting the front derailleur to shift good between the two rings because of the 16 tooth difference. But you would probably have to replace the front derailleur with one that would swing back and forth enough to cover a triple.
The first thing I would do is see if I could get two new chainrings for your existing crank that are a few teeth smaller. If you currently have a 42/52 you might be able to get something like a 38/50 and solve your problem inexpensively.
I have put a mtb triple on my mid 70 bike because of the hills around here and I have some old legs. I still struggle up some of them with a 24 chain ring and a 24 cog. I really like the set-up for the steep hills. I can still got along at 17 mph or so and not even need the 44 chain ring. When I get up to 25+ mph I just coast down the hills. And again I almost never need the big chain wheel. My crank set is a cheap steel one but I never notice. I also have a road triple with almost identical low gearing and I never use the big 52 ring. There are not many fellas that can spin out a 117 gear. At least I know I can't except on a big descent and I would rather coast and enjoy the ride.
Sorry, got off track. I use long cage rd and mtb fd on the mtb crank set-up and friction shifting on both bikes but I am an old fart and grew up with friction. Maybe one of these days I will get to ride a bike with brifters.
05-15-09, 08:51 AM
You can get a beautiful Sugino XD-2 and the appropriate cartidge bottom bracket at rivbike.com, among other places. I would replace the front derailer with one made for a triple.
05-15-09, 09:12 AM
Just thinking now, maybe changing the rear gearset would be easier and cheaper. You know, like with a hill climber 1st gear.
05-15-09, 11:02 AM
I still contend that finding smaller chain rings up front for your existing crank is your most cost-effective solution.
05-15-09, 11:04 AM
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