Thanks everyone for the tips. I do like to get some high speeds on the down hill and take some rough trails and even get some air from time to time. Don't want to get myself bent or broken, so I'm going to go with a used 29er. Don't know what I'll do with the Schwinn.
converting vintage frame to modern mountainbike
- Thread starter harquahalas
- Start date
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Beau said:...
Now here is the problem. Old frames were not used to having stiff parts on them or the stresses that modern parts provide. The headtube can "stretch" or flare if you run a long travel fork (and mess up the geometry REALLY bad). I have also flared out bottom brackets with stiff BMX cranks.
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Really? If I run modern bmx cranks on an old-style 26" frame with an american BB, I might damage the BB shell? Would this be with hard riding, or even while JRA?
thanks for any info,
-rob
stumbled on this thread while trying to do this myself... my results did not go as planned.. not enough room for rear wheel in the frame.. even went down to a 24" wheel
going to see if i can't either find or make a single sprocket three piece now and just throw a coaster brake on instead because I really like the way this thing is starting to look
using a Hawthorne (Hercules built) frame with a Specialized Hard Rock GX donor bike for most of the parts so far. the paint almost matches perfect too.. the forks are from the Specialized bike
going to see if i can't either find or make a single sprocket three piece now and just throw a coaster brake on instead because I really like the way this thing is starting to look
using a Hawthorne (Hercules built) frame with a Specialized Hard Rock GX donor bike for most of the parts so far. the paint almost matches perfect too.. the forks are from the Specialized bike
Bicycle808 said:
I ran Technique cranks on an old Schwinn and even those rounded out the BB over time. Before the cranks cracked!!! I was just using mine for daily commuting.
1 1/8" threadless fork, Technique 3 piece cranks, DX SPD pedals and more. Some a-hole stole this one from me. The only bike I have ever had stolen.
Have you ever tried to manual or wheelie a cruiser? It doesn't work to well.
For those who mountain bike the question is not what can be used but how heavey and reliable the end product is. If you ever rode one of the old MTB's then jump on a newer one you would never go back. Some times it is more about style so weight does not matter but in MTBing weight and reliability is everything. Do not want to push a bike 10 miles to get out ot the woods. If you ever read anything about the old Klunkers they tell how heavy the bikes were because they were the strongest frames at the time but you will notice most of the riding was down hill.
If it is just going to be used on a rails to trails weight is negotiable.
If it is just going to be used on a rails to trails weight is negotiable.
Beau said:
Beau,
Love your ol' schwinn. A shame it got stolen.
Are you saying that techniques killed the schwinn's *BB*, or the BB *shell*? I wanna put profiles on my worksman, b/c i think that sort of waste illustrates my emotional problems pretty succinctly. But, really, I don't want to run profiles if it's gonna shroom out the BB shell...
Never tried to manual on a cruiser, but if you watch the special features of "Klunkerz", Billy manual on his ol' schwinn for days after he goes over the tech aspects of the bikes. He made it look easy. Sittin on my mock-up version of my bike, it seems like it might be hard.
-rob
No! The fact is, Technique cranks were known to crack and fail! The fact that they did that to the frame was amazing to me! I had them welded up a few times.
Profiles may work! I ended up hammering my BB, knurling the cups and adding loc-tite. I rode the bike pretty hard though.
The manual point on these frames is WAY up. The chainstays are loooooooong and the have higher bottoms brackets. Some riders are simply amazing though. I saw a guy ride a wheelie on a recumbent. That is an amazing site!
Profiles may work! I ended up hammering my BB, knurling the cups and adding loc-tite. I rode the bike pretty hard though.
The manual point on these frames is WAY up. The chainstays are loooooooong and the have higher bottoms brackets. Some riders are simply amazing though. I saw a guy ride a wheelie on a recumbent. That is an amazing site!
Beau said:
My plan is to build a bike mostly out of recent production US-sourced stuff,and get it looking the ish, even if it's not the real deal. I'll probably shed fenders and run knobbies and roll thru the pins and other low-impact trails on it, but i mostly want it for "just ridin'" duty-- coffee shop, the pub, to work when i'm not running late. For fun, basically. But, it won't be a lot of fun if i need to fuss with the BB frequently. I guess i gotta just take her easy.
*edit* it'll probably help if i get the crank install dialed in perfect from day one. I imagine any play in it would just exacerbate things.
-rob
In my experience, finding that spot where bearings have little or no play, but are not quite binding makes a world of difference in longevity and rideability on any bike. On cheap bikes it can mean the difference between decades of use and an unrideable pile of junk. :|
don't know if it helps my case, but i'm not building an actual vintage frame, just a vintage-style one. It's a heavy-duty worksman industrial newsboy. They say these are s'posed to be bomb-proof frame, but i think the emphasis is more on "heavy" than on "duty". I'm not so sure that the BB shell would take any more abuse than the old schwinns and such would...
-rob
-rob
deorman said:
I think he meant the press fit of the cups into the BB shell. Often times, on older frames, the cups can be put in by hand. Meaning a loose fit. Adding loc-tite or knurling the BB cups helps keep the tolerances tight from the get go.
i meant getting all aspects of the install down pat, from the press-fit BB to the spacers to the adjustment of the bearings. I haven't installed profiles in my life, but i reckon the sealed bearings will make that aspect of the install a little easier than loose-ball set-ups. The frame is brand-new, never ridden, and it has the oem cheap chinese cranks installed right now. I'm hoping that i can remove those and the tolerances will be on-point for the profiles, but if not, its good to know that loctite could help in this case.
thanks!
-rob
thanks!
-rob
You shouldn't need loc-tite for those.
The biggest thing you need to do is make sure the center spacer is the right width. I figure it out by assembling the BB out of the frame and just holding it up against the outside of the BB shell. Either adding or reducing width until it is the right width at the BB cups. Then space the sprocket so it's as close to the chainstay on the drive side. Measure the distance between the crank arm on the drive side, and space it to match on the non-drive side.
If you center spacers are correct, you can tighten the cranks down tight and you want have any binding or adjusting. I like to use blue loc-tite on my3-piece cranks to keep things tight.
The biggest thing you need to do is make sure the center spacer is the right width. I figure it out by assembling the BB out of the frame and just holding it up against the outside of the BB shell. Either adding or reducing width until it is the right width at the BB cups. Then space the sprocket so it's as close to the chainstay on the drive side. Measure the distance between the crank arm on the drive side, and space it to match on the non-drive side.
If you center spacers are correct, you can tighten the cranks down tight and you want have any binding or adjusting. I like to use blue loc-tite on my3-piece cranks to keep things tight.
