abdon 

I'm picking up this baby tomorrow. My daughter wants a trail bike now, I plan on waiting her out to eventually turn it into a 650B tourer. We old people plan for years down the road.


Can you tell the year by the color scheme?

Right now the plan is to, well; for starters fix that rear tire. From there the usual servicing, rewiring, upgrade the drivetrain to 8 speed cassette (should have a 7 speed freewheel), and more likely than not drop bars on a nicer stem with bar end shifters.

Then I wait. Muahaha...

CO_Hoya 

Are you confident that it is an MB-1? I associate the upper tier Bridgestone MBs as having the "Comp" designation while the lower tier having "Trail" or "TrailBlazer".

It's a fully-lugged frame, at least, which is a good sign.

katsup

Looks like a MB4 to me. MB1 should have a Tange Prestige sticker and XT components.

RB1-luvr

I'd say that's an MB-4 Trail. Still should be sufficient for your future evil plans.

nlerner

Also, wheel size is 26"/559mm. A 650B wheel is 584mm. I don't think it would work unless you have someone move the canti posts.

bikemig 

I think you can do this if the cantilever has sufficient vertical adjustability.

https://velo-orange.blogspot.com/201...t-to-650b.html

I could never figure out why you might want to make this swap other than to feed the need to tinker with a bike. 26 inch tires and rims are widely available.

abdon 

Well I'm not gonna lie, feeding the tinkering need is important, but on an touring bike the larger wheel just works better all around.

I never liked 700c tires on a dirt bike (nor understood the need to call them 29"). To me the smaller 26" wheels are better for rolling over stuff. On an open road (again, to me) a larger wheel works better. This frame has the geometry suitable for a touring bike with the slightly oversize tubing to make it bulletproof in the face of loaded touring. 650b just happens to be the largest wheel size it will take with enough clearance left over for reasonable tires and fender.

I have canti brakes that should have enough adjustment to reach but if it gets to this point I'll probably reposition the studs as part of doing other frame modifications. You'll be surprised how far I can take the need to tinker

mrv 

i would not be surprised

https://www.bikeforums.net/classic-v...e-project.html

ironwood

MB-1s and MB-2s did not have unicrown forks. Although I like 650B tires, and have converted bikes from 27" to 650B, I wouldn't bother with converting MTB. Just get a good set of tires.

abdon 

There are benefits that make the conversion from 26" totally worth it. For starters it is about the intended purpose of the bike; for long distance touring on mostly road the larger wheel and skinnier tires you can pump to 80psi really shines. A large 26" tire can't see those pressures and you end up with a lot of rolling resistance. You can put skinnier tires on 26" but then again they get even smaller. Having the ability to make it happen it is a no brainer.

mrv 

https://www.paulcomp.com/shop/compon...akes/motolite/

i was considering these as an option for a steamroller that I want to run 700 & 650b on- after adding canti posts.
paul had a video installing them on an old mtb.

I’ve subsequently talked myself into long reach Tektro calipers instead. I’m thinking for resale a steamroller rider isn’t going to find canti brakes on a SSFG an interesting combo.

merziac

Really?

https://sheldonbrown.com/bridgestone/1992/1992.pdf

Actually many/most of them did until the last 2 years, 93, 94.

kunsunoke 

MB-1s and MB-2s did have unicrown forks, for quite a while, in fact. They started using unicrown forks in 1986, per Sheldon's catalog collection. My 1990 MB-1 had a Ritchey Logic unicrown before it was replaced by a Mag 21. The biplanar forks everyone raves about started in 1993 and lasted until Bridgestone pulled out of the market, thanks to yen shock.

Have tried to convert a 90's era Stumpjumper to 700c. The conversion was a bit of a hack job (due to the brake setup that was required), and the bike had much higher bottom bracket height than was comfortable to ride on anything that wasn't bolder-strewn. Not worth the effort, IMO. Drop bar conversions at 26" are a better bet.

abdon 

The nice thing about the 650b conversion from 26" is that when you replace fat 26" tires for skinny 650b tires the outside wheel diameter doesn't change all that much which means that the bike geometry and handling doesn't change all that much. What you gain is much higher tire pressure that reduces rolling resistance by a lot and a lot less weight on the tire.

nlerner

Couldn’t you just do that with a narrower (say 1.5”) 26”/559 tire? Sure the BB will be lower, but for my tastes, “classic” MTB geometry is too high of a BB.

abdon 

Yes, you can certainly do that and I still have a set of skinny 26" rims with skinny 26mm road tires from an early interaction on one of my daughter's bikes. The already small 26" tire really shrinks something fierce.

There are significant benefits to be had but there is a significant amount of effort and cost; it is up to you if the squeeze is worth the juice and there is certainly no wrong answer. It also depends on what your end goal is.

You can cyclotour on just about anything, but when you plan to do looooong loaded rides life is a lot more fun if you hit the nail in the head when it comes to split rolling resistance and comfort.

I'm looking at two wheels I have here; a standard 26" tire with 1.95" tires, a 650B with Gran Bois 32mm tires. Funny enough both have pretty much the same outside diameter, 26 1/4". The 32mm tire can be inflated to 80psi for a lot less rolling resistance, less rubber contact on the road, it offers a superb amount of comfort for road riding and even fine gravel, it has a lot less terminal weight, and it keeps the exact same geometry on the bike.




But on a budget yeah, slap a 32mm tire on the 26" rim and you'll get most of that benefit. The cost is a smaller tire, less revolutions per crank, and geometry changes; the lowering of the bottom bracket can affect the handling of the bike. I like my tourers dead stable a speed so I can eat while riding.

Korina

As a 5'4" rider, I much prefer 26" wheels, as well as shorter cranks, which tall people never think about.

SoCaled 

1988 MB-4 Trail

abdon 

Yeah, when I picked it up I was able to see it was the MB4.

As I suspected the frame was a bit too tall for my 5'2" daughter with short legs. As providence would have it at the local bike collective I picked a tiny slanted tube MB3 frame for $10 bucks. I'm currently transferring the components to that one and stashing the MB4 frame for a future 650B touring bike project. It is a pretty fantastic candidate for that.


She wants to ride it now but eventually I'm going to clean and just clear coat that frame.

One complication; the seatpost on the MB4 was pretty much welded shut... No heat, nor cold nor oxalic acid, no brute force in, out, around, would make it budge. As I type this it is outside being soaked in sodium hydroxide (lye) so I can dissolve the seat post in place...

abdon 

Like my daughter you are a good candidate for 650B. 26" tires shrink a lot on skinny rubber, 650B lets you have your cake and eat it too by maintaining the correct geometry. You can go full road width with Continental Grand Prix tires (23mm), get yourself comfy cushion with my favorite Gran Bois 32mm for city and touring, and (bike permitting) big fat chunky tires for trailing.

Korina

My Maxxis DTHs are anything but shrunk. What I'm hearing is a lot of what you like. Does your daughter have any opinions or does she not know enough to have them yet? My husband does this a lot and I have to remind him that me, my bike, and my riding are different from him.



Getting ready to start the Critical Mass ride.

bikemig 

+ 1 on this and a beautiful bike by the way.

Korina

Thanks. Some day I'll browbeat (more likely whine) my husband into digging out and installing the new drivetrain.

abdon 

She does. She actually knows a lot about bikes. She may ignore a lot of the things I may say on a wide variety of subjects but when it comes to bikes and back country snowboarding we share a lot of the same biases and she has come to respect my reasoning.

She knows the benefits and hindrances of tires on a given situation. She is extremely happy with the 26" going on her hard tail bike, the 650B on her tourer, and the 700c on her road bike. On that last one we both know she'll be a lot happier once we find darn 165mm cranks for it.

Korina

That's great to hear! Although at 5'2" she'd probably be better off with 160 or even shorter. If you have some disposable income, these guys make cranks down to 130mm. And here's a guide to figuring out how long she may need. Proper length cranks will save her knee and hip issues down the road. HTH.