 |  | | | |  | |  |  | Ideas for the 84 Sprint |  | |  |  | |
 Posted: Sat Oct 04, 2008 7:21 am |
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| scozim |
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| Joined: 26 Sep 2008 |
| Posts: 629 |
| Location: Ellensburg, WA |
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I took the Sprint out for a shakedown ride on Thursday and had flashbacks to the 1984 Peugeot I had during college which means there was a big smile on my face. A very nice ride with the drivetrain absolutely silent. That was a nice change over my '97 Bianchi's drivetrain.
Some questions, though (bear with me - I'm new to the mechanical side of these things):
1) I'd like to keep most of the components stock as long as possible but am eyeing subtle upgrades. The 6 spd freewheel is ok but I wouldn't mind a 7 or 8. The rear seems to be 122 mm - I'm assuming I can go to a 7 spd ok but an 8 would require spreading the frame and I'm not sure if I want to do that. If I just go to a 7 spd do I have to have a Maillard Helicomatic freewheel or will another work? Do I need to change the rear hub?
2) I'm adverse to triple cranksets - it's a personall thing. I'm assuming it would it just be easier to change the 42T chainring to a 39T or even go with a compact double and leave the freewheel alone?
4) How many of you have upgraded the wheels? If so, did you leave the hubs original or change them. The bearings have been repacked on my front hub and it's really, really smooth.
5) On the ride on Thursday, when I stood up to pedal I periodically could hear a twangy sound from the crank/bottom bracket area. Everything feels tight so I'm not sure what it is and I only hear it when I stand up? Ideas for my investigation? I'm going to have this on the trainer all winter so it won't be getting stressed. |
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| | | | | | | | | Re: Ideas for the 84 Sprint | | | | | |
| Posted: Sat Oct 04, 2008 10:54 am |
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| verktyg |
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| Joined: 14 Jan 2007 |
| Posts: 2814 |
| Location: SF Bay Area |
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| scozim wrote: |
1) I'd like to keep most of the components stock as long as possible but am eyeing subtle upgrades. The 6 spd freewheel is ok but I wouldn't mind a 7 or 8. The rear seems to be 122 mm - I'm assuming I can go to a 7 spd ok but an 8 would require spreading the frame and I'm not sure if I want to do that. If I just go to a 7 spd do I have to have a Maillard Helicomatic freewheel or will another work? Do I need to change the rear hub?
2) I'm adverse to triple cranksets - it's a personall thing. I'm assuming it would it just be easier to change the 42T chainring to a 39T or even go with a compact double and leave the freewheel alone?
4) How many of you have upgraded the wheels? If so, did you leave the hubs original or change them. The bearings have been repacked on my front hub and it's really, really smooth.
5) On the ride on Thursday, when I stood up to pedal I periodically could hear a twangy sound from the crank/bottom bracket area. Everything feels tight so I'm not sure what it is and I only hear it when I stand up? Ideas for my investigation? I'm going to have this on the trainer all winter so it won't be getting stressed. |
1. If you have a Maillard Helicomatic rear hub your choices are limited. There were no real standards for rear hub widths until Shimano introduced their SIS index shifting.
Rear hubs for 5 speed freewheels were supposed to be 120mm wide across the lock nuts (OLN - over locknut dimension)... but they ranged up to 124mm or 125mm wide.
The standard width for 6 speed and 7 speed hubs was 126mm but 125mm, 127mm and 128mm widths were also used.
Helicomatic freewheels came in 5 speed, 6 speed "narrow" and 7 speed "narrow" configurations. I've seen specs that indicated rear sprockets were produced in sizes up 28T, 30T and 32T. The larger sizes are pretty rare.
The Yellow Jersey Ltd. still has a reasonable selection of Helicomatic parts.
http://www.yellowjersey.org/helico.html
Sheldon Brown's (RIP) website has a good view of a Helicomatic hub and freewheel. Also some info on older French bikes with metric dimensions that probably don't apply to your bike.
http://www.sheldonbrown.com/velos.html
Trying to switch to a 7 speed Helicomatic can become a can of worms. My suggestion for now would be to get some larger rear sprockets or a bigger Helicomatic freewheel and a smaller front chainring (see below) and ride it into the ground before making any major changes t the rear wheel.
Freewheels were outlawed in the Tour de France until the late 30s. REAL MEN raced with single speed bikes! It doesn't take long getting used to a 6 speed. At least a third of the gear combinations on most bikes overlap.
2. You have a Stronglight 104 crankset with a 122mm BCD (Bolt Center Diameter. This site explains chainwheels:
http://sheldonbrown.com/harris/chainrings.html
I'll PM you on 38T chainwheels.
http://harriscyclery.net/itemdetails.cfm?ID=1948
4. "If it ain't broke don't fix it!" Go ride the thing! 
I have Mavic Module E wheels on several bikes. They are over 30 years old but still run fine. They are nice light weight wheels. New low spoke count wheels aren't going to add much to this bike.
Think of it this way, if you are a bike manufacturer and build 100,000 sets of wheels a year with 36 spokes each, switching to 32 spokes per wheel saves 80,000 per year. Not only are you saving the cost of the spokes but the labor assembling the wheels. That's why the switch was made from 36 spokes to 32! 
Now if you go to 28 spokes..... 
5. First thing to check is the torque on the bolts holding the cranks onto the bottom bracket spindle. They should be tightened to 30 Lbs. torque. I'll bet that they are loose.
Chas. |
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