loubikes

I want to convert this Motobecane into an around-town, short-distance light-trail bike for my wife. She would be biking a kid on it, running errands, typically traveling 1-4 miles through the city. We have some decent hills and she wouldn’t want to get going too fast nor have the opportunity to really.

My main thoughts right now:

• Change drive train to 1 x 9. This means cold setting frame from 120 to 130. She’d prefer to only have one shifter to worry about and so I’d like to get up to at least 9 to give her some range.
• I was going to switch bottom bracket for Velo Orange threadless bottom bracket
• Switch wheels from 27” to 700c. It seems the brakes will reach and this will help accommodate wider rims and tires (~40mm) so we have the option for light gravel/dirt paths.
• Will she have enough gear range with 1 x 9? Suggestions on range? Front chain ring size? Should I reconsider and do 2 x 9?

I’d love suggestions for any components but here are some:

> What Wheels? Where would you buy them from? New/Used?
> Chain-ring/Crank Arms?
> Rear Rack
> Derailleur


Any other thoughts/suggestions? Things I’m likely not considering?


Thanks!

Bill Kapaun

It's going to be a major money pit.
Search Craigslist or similar for something that's already close.
I ride 3x9's, but pretty much use them as a 1x.
You don't have to shift the front if you don't want, but that occasional hill, head wind or whatever may wish you had the gear you need at the time.

AnkleWork

+1
Knowing nothing of your wife or where she'll ride, I must suggest a wide ratio 3x11 drivetrain so she can pick which ever gear she wants. In any case don't just go get a whole suitable bike. HTH

HillRider

As Bill noted, the changes you propose will be a major money pit and really not worth it. I also suggest finding a much more suitable bike either new or used. A decent 9 or 10-speed Hybrid should meet her needs and, as noted, a double or triple crank can be treated as a single chainring by just not shifting it and at far lower cost.

HerrKaLeun

If she prefers 1x , then don't listen to some stranger on the internet talking you in 3x. That stranger won't hear her whining to you ...😭

1x11 has enough range for hilly areas as long as the chainring is selected properly. So a 1x9 may work in flatlands. But assuming you buy new anyway, just go 10 or 11 speed.

For reference, I have a 36T chainring and 11-42 cassette on my hybrid. We have some 10° hills. I never need lower, and never spin out. With 11 speed the gaps are just perfect.

Money pit or not, you can reuse the drivetrain if you sell or dispose of this bike. Just keep the old drivetrain to put back on. Spend $20 more to make her happy and enjoy riding simple 1x.

Kapusta

To echo a previous poster:

If she wants 1x, then go 1x.

Also, if you are getting a new shifter, RD, and cassette anyway, go 1x10. While 1x11 is also and option, there are a few more issues you may run into in this particular situation that may be a headache.

As far as the gearing.... nobody can possibly tell you how low of a gear she will need. I would get a 11-36 cassette, and try different chainring sizes..... but that will depend on the crank. What kind of crank is on there?

But the other posters do have a point that by the time you buy a new drivetrain, and new wheels, you might be better financially and hassle-wise with a different bike.

Of course, if there is a personal attachment to this frame and you simply like to tinker and customize, then go for it.

You might consider getting the Shimano Deore 1x10 group with the 11-42 cassette. You’ll know it all works together.

dsbrantjr

It is your bike and your money, but your plans sound like it might be more practical and similar money to sell that one and buy a new bike. Since your wife doesn't want complex shifting an alternative might be to get a bike with an internal-geared hub; then she could even shift while not moving, handy with a child carrier. Bikes Direct has several IGH models as do some of the other manufacturers.

cny-bikeman

If you're going single chainring then make sure that the chanring is not too large, especially if the small cog is 11 or 12. I think it's absurd when limited to a single ring to go larger than 48 for a less strong rider. Even a 46 at 80rpm gives her a speed of 25mph with a 12, 27
with an 11. Doing so allows a low gear without too large a jump between gears. If you need to in order to get a lower gear 44 would be fine as well.

That being said, I agree that changing wheels and drivetrain is a lot of time and money to put into the bike. I would suggest you open yourself up to other possibilities, such as a Nexus 8 speed bike starting at $400, or a used women's hybrid bike that would at most require a crankset and perhaps a larger range cassette, then sell the mixte. I will, however, note that I have a soft spot for Motobecanes, and yours looks to be in great condition, so if that's your choice have at it.

HerrKaLeun

+ 1. My 36T chainring still gets me to 30mph at around 100 rpm and most riders are not strong enough to go that fast on level ground. At least not for long enough to matter.

Bill Kapaun

Determine what gear range your wife finds "usable".
Go to an online gear calculator and match up the ratio's.

You may find on 11 speed that you have enough "useless" cogs that you'd be just as well served with a 9 speed with a "more coherent" cog selection.

I you intend to spread the frame from 120 to 130, you MUST get the drop outs realigned to parallel or eat hub bearings. I won't go over 4mm by just "springing the frame".

Miele Man

Do you have a bicycle co-op close to you? They can be a great source of quality yet low price to you parts. Co-ops are often a great place to get decent condition wheels and tires.

How are the brake calipers on that bike? do they flex much when used? Also, do you have the 4 to 5 mm in the brake block slots to lower the brake pads that amount? that's needed if going from 27" to 700C wheels.

Measure the space between the chainstays near the seat tube to be sure you have room there for a 700C x 40mm tire.

Also, going to a wider hub will mean you'll probable have to cold set the rear triangle and realign the rear dropouts to get the wheel t o fit in those dropouts. Cold setting is NOT that hard to do if you're careful. Sheldon Brown (RIP) has a great article on how t o do that.

https://www.sheldonbrown.com/frame-spacing.html

Do want advice on a rear luggage rack or a rear mounted child seat?

When I built up my 27 gears bike I built up the cassette as a 7-speed plus 2 bailout gears for the wind or steep inclines on overpasses. You might want to do something similar with your 1x9 setup. The size of the chainring and the highest gear cog (the smallest # of teeth cog) will depend on how fast she plans on riding. You can look at a gear calculator such as Sheldon brown's one to get an idea as to what different gear combinations will give you.

https://www.sheldonbrown.com/gear-calc.html

Good luck and cheers

Cheers

loubikes

Hey Bill, thanks. Can you tell me roughly the size of this money pit? I am expecting it to cost more and I've been pricing-out bottom brackets, drive trains and wheels (mostly looking at used items). What will be my biggest cost? Rough total-range? Thanks!

loubikes

Thanks for the encouragement and your drive train details, that was helpful.

loubikes

This.

Sounds like good advice. It seems tricky buying used/mismatch without knowing much about drivetrains.

loubikes

Ok, thanks. I was hoping I could not worry about this. Others agree? This would do serious damage to bearings?

loubikes

They don't seem to flex but I definitely haven't thought deliberately about that, I'll check it out. Yeah, I've taken measurements and it seems like the brakes will reach if I file the slot out a bit. I haven't measured for tire width ... it just looks so roomy but I better do that. Thanks.

Yeah, Sheldon Brown's articles are what gave me the push to try it.

What i plan to do is put a luggage rack on the back that will occasionally carry a Thule Yepp Nexxt Maxi. I have two of the older models on other bikes and they've been great.

I guess I can put any rack on there and just use "p-clamps"? That seems like the best option I've found so far. Thoughts?

Miele Man

If you were replying to my post then you're quite welcome.

Sometimes we have an old bicycle or frame that we really like for whatever reason. It might be a High Tensile Steel one even but perhaps it really rides nicely or we just love the way it fits.

One time I combined parts of a 27" wheel bike (frame and rear wheel) and a 24" wheel bike (front fork and wheel) and made myself a fixed-gear funny "Pursuit" bike for tooling around the parking lot on. It was a fun bike.

Good luck with your build.

Oh, yes, do get those dropouts realigned so they don't cause undo wer on the hub bearings or worse yet break off in use.

Cheers

Mad Honk 

Loubikes,
I was around when those Motobecanes came into the country for about $79 dollars per frame, and $179 complete. Now a few years later we have discovered a weak front fork in many of those older frames. I have one friend who has spent a few thousand dollars from that damage, and you are telling me you want to put your wife and child on one of them. I am in complete disagreement with this decision. From what I see it is a nice bike, but adding wheels and tires, and new crank parts and a new rear derailleur, and whatever freewheel, and a rack, along with either a trailer or bike mounted seat for your child will be in excess of $300 minimum. For that amount even an inexpensive new bike can be had with none of the hassles you are going to go through trying to make all of this work, and have a new bike with a far lower chance of damage to both of your significant others.
Again your current bike looks nice and may be very service-able, but if in my stable it would be looking for another home or a trip to the glue factory.
Just my opinion based on current knowledge of these bikes. MH

Bill Kapaun

Just where have I given you BAD ADVICE?
When you clamp it down tight, it bends the axle to some degree. The bearings aren't running in the orientation they are designed for.
A 10mm spread is going to eat bearings fast, because it bends the axle way too much.
As I mentioned, I wouldn't go over 4mm.
I've eaten too many bearings.

I still think converting that is beyond stupid. If you like it, hang it on the wall and look at it.
I've been down that path when I first started wrenching bikes.
AND, you have the added "benefit" of FRENCH.

loubikes

MH, really sorry to hear about the damages your friend suffered. Thanks for telling me about this. Seems like this is something I could further research. Do you have any more information about the years/make/model of these weak forks? Could you direct me to some more information about this online somewhere? Anything would be appreciated, thanks!

loubikes

Hey Bill, sorry if you thought I was insinuating that you gave bad advice, I really appreciate everything you posted. I was just looking for other's to add support to your statements (and they did! the power of crowd-sourced-knowledge!). I feel all the more confident that this is something I need to do now. Thanks again!

HillRider

This is a real consideration as the threading of the bottom bracket and headset won't be compatible with any readily available components and the tubing sizes will also likely be uncommon. You appear to be aware of this as you mentioned a Velo Orange threadless bottom bracket but the problems will extend beyond the bottom bracket threading.

Mad Honk 

Loubikes,
The latest incident was on a late 70's mixte frame and fork. My friend had one back then and tried to bring this one back to life. She was on the first ride when the fork snapped and sent her tumbling into the ER. I have noticed damage to some of the others that have shown up in our Co-op, mainly bent forks, that are butter soft and will bend back out of shape after straightening and re-install. The tubing on those bikes was not a very high end tubing, and they likely are rusting out from the inside. For the lower end market I doubt they did nothing more than give the frames a paint coat and decals.
I suspect that our friends here on the forum could point you to some nice complete bikes that have the features you are asking for that IMO are going to be far safer for you family. When thinking about all of the upgrades you are mentioning it isn't going to be more money if any, to get a new ride. Smiles, MH

alcjphil

The bike referred to in the photo from the OP is an EARLY 70's Motobecane, take note of the cottered crank. This bike was a contemporary of the Peugeot UO18 Mixte. Too bad that the photo of the bike provided by the OP doesn't show the Huret drivetrain. The bike is beautiful, apart from the hideous bar/stem conversion

Homebrew01

A used hybrid for $75.
Done