Old Motobecane advice
05-05-20, 08:12 AM
#1
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Old Motobecane advice
Hey everybody,
New here and definitely not a bike expert but am wanting to pick up as much as I can. I moved to France last year and managed to buy an old motobecane for 25 euros! Bargain! Thought it would be a great project and seemed to be OK condition, I believe its a late 70s model grand touring or grand sprint.
My problem started the second time I rode it, the pedals had been replaced by previous owner and he had stripped most of the thread on the crank so the pedal snapped out while I was riding. Since everything I've tried has been difficult, a mixture of trying to source tools and everything being rusted into place.
At the moment I've removed the crankset and want to remove the bottom bracket so I can spray as much wd40 down the frame as possible to unstick the rusted in seat post. The left crank arm is unusable and the right is ok but not great and I'm questioning whether to replace the full crankset and bottom bracket but I know this will be hard to find, and may require me to start replacing other parts.
My question is, do you think it's worth just replacing the bare minimum and repair as I go ie just replace the left crank arm and just regrease and install the bottom bracket. Or should I just go full hog and strip it and replace everything, full new crankset, bottom bracket, cassette etc.
Sorry for the long post! And sorry for any mistakes I've made, just want a bit of advice before I go down an unnecessary expensive rabbit hole.
Many thanks!
New here and definitely not a bike expert but am wanting to pick up as much as I can. I moved to France last year and managed to buy an old motobecane for 25 euros! Bargain! Thought it would be a great project and seemed to be OK condition, I believe its a late 70s model grand touring or grand sprint.
My problem started the second time I rode it, the pedals had been replaced by previous owner and he had stripped most of the thread on the crank so the pedal snapped out while I was riding. Since everything I've tried has been difficult, a mixture of trying to source tools and everything being rusted into place.
At the moment I've removed the crankset and want to remove the bottom bracket so I can spray as much wd40 down the frame as possible to unstick the rusted in seat post. The left crank arm is unusable and the right is ok but not great and I'm questioning whether to replace the full crankset and bottom bracket but I know this will be hard to find, and may require me to start replacing other parts.
My question is, do you think it's worth just replacing the bare minimum and repair as I go ie just replace the left crank arm and just regrease and install the bottom bracket. Or should I just go full hog and strip it and replace everything, full new crankset, bottom bracket, cassette etc.
Sorry for the long post! And sorry for any mistakes I've made, just want a bit of advice before I go down an unnecessary expensive rabbit hole.
Many thanks!
05-05-20, 08:37 AM
#2
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Welcome. There are two issues: stuck seatpost and BB/crank.
Rather than removing the BB so you can spray WD40 through the seat tube, I'd start with Kroil instead of WD40. Dribble at the seatpost cluster from the outside, let it soak for a day or two, come back and see if you can get the seatpost to move. Repeat until you get it to move more and finally out. Lot less hassle than spraying something up from the BB.
As to the crank and pedals, if you can find suitable replacements - don't have to be new - then by all means, go ahead and replace. No need to retain worn parts.
Rather than removing the BB so you can spray WD40 through the seat tube, I'd start with Kroil instead of WD40. Dribble at the seatpost cluster from the outside, let it soak for a day or two, come back and see if you can get the seatpost to move. Repeat until you get it to move more and finally out. Lot less hassle than spraying something up from the BB.
As to the crank and pedals, if you can find suitable replacements - don't have to be new - then by all means, go ahead and replace. No need to retain worn parts.
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05-05-20, 09:03 AM
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I would replace the crank but the bottom bracket can be saved by cleaning and regreasing.
Congrats on the bike. My 78 grand touring is amazing.
Congrats on the bike. My 78 grand touring is amazing.
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05-05-20, 09:57 AM
#4
Senior Member
I would get the seatpost out first. No point in making other repairs if you cant get the post loose. Next crank/pedal repair or replace. Are the threads 9/16 inch? If they are 14mm you may be able to repair. Only after seatpost and crank are fixed would I move on to service bearings (all) and new cables.
Don't loose sight of your option to resell this bike and find another in better condition. I imagine there are a few more classic Motobecanes in France.
Don't loose sight of your option to resell this bike and find another in better condition. I imagine there are a few more classic Motobecanes in France.
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