Monday, June 22, 2009

650B Conversion Hits A Wall

In my last post, I wrote that the 650B conversion project rolled forward when I purchased a set of new 650B wheels to go on the 1976 Schwinn Le Tour 10 speed frame. I was really jazzed because I knew all I had to do was slap on the new wheels, fiddle with the brakes and I'd be good to go.

Unfortunately, it didn't quite play out that way. I knew there would be an issue with brake reach, as the calipers would have to reach down a little farther from the old 27 inch wheels to the 650B size, about 23 mm more, or 9/10th of an inch.

650B wheel using stock brake

Knowing brake reach would be in issue, I ordered a set of Tektro 556 long reach brakes. These brakes range from 55mm to 73mm from the center of the mounting bolt to center of rim. This was complicated by the fact that the supplier sent only the rear brake, but they've acknowledged the error and have put the front brake in the mail.

However, I wasn't prepared for the disappointment when I got the brake and found that it's no longer than the stock brake that came on the Schwinn!

650B wheel using Tektro 556 brake

In the next picture you can see that I am pinching the calipers against the rim. You can see how far down the mounting bolt needs to be.

Pinching the calipers against the rim to simulate the desired mounting position

The stock brakes have a long hex bolt with nut that runs through concave shaped nuts that hold the brake in place against the horizontal brake mounting tube. The Tektro brakes use recessed mounting. I've read that I can drill the rear hole in the tube and in the fork crown to allow me to use the recessed nut. I've also seen Sheldon Brown's "drop bolt" solution. Any suggestions?

Stock brake on the left. Tektro 556 on the right. Notice the reach is about the same.

Today I got the Panaracer 650B x 38mm tires in the mail. They were about $20 a tire and have an interesting inverted tread. My LBS is ordering some 650B tubes for me.

So, again at a cross roads, I am not sure what to do. Here come the obligatory lists.

Continue to 650B-ify the Schwinn:
  • drop bolts on brakes (ugly, but cheap)
  • have frame maker move the mount (pretty, but expensive)
  • find longer reach brakes, if they even exist (probably expensive)
Abandon the Schwinn/650B project:
  • Convert it to 700C and use the original brakes
  • Convert it to 700C and use the Tektro brakes after figuring out to to use the recessed mounting bolts
  • sell the 650B wheels
  • keep the 650B wheels and find another frame
As usual, I welcome your comments and suggestions.


brady said...

Practical and cheap (and I trust Sheldon's safety judgment) but dang those drop bolts are an ugly solution.

Cutting and moving the mount would also require painting. If you're gonna paint a little, you may as well do it all. Long and expensive process. I wouldn't go this route unless I was absolutely set on 650b on this frame and no other solution presented itself.

I'd hold out for some longer brakes. There out there somewhere. Did Mike the S. Omaha shop suggest the Tektro 556 long brakes? Otherwise, he should be able to help track the old school long reachers down. Good luck!

Scott Redd said...

Thanks Brady. Paying for frame work on a Schwinn seems a little extreme. Now if I were to take up welding as a hobby and did it for fun, then it might be workable. Can you do this kind of work on steel with a torch?

I settled on the Tektro 556 when reading about similar conversions. I may search and see if there are any brakes that can reach down another inch or so.

One drop bolt idea was to get some aluminum stock from the hardware store and drill holes in the right place to make a bracket that would drop the brake mount hole down a bit. I wonder about the bracket pivoting against the curve of the existing brake mount tube.

Also, I expect to have similar issues on the front wheel and fork crown, as well.

I need to make sure I know when to quit. Going 650B just for the sake of going 650B is the wrong reason. In the end, it's got to make sense.

One thing's for sure, I need to get a little ruler with metric markings on it.

Steve said...

I've drilled the mounting holes for brakes on older bikes, and it works just fine. Sometimes on the rear tube you've got to drill the entire way through the tube from the backside of the bike due to difficulties in getting a drill to the other side of the frame. This means the bolt doesn't fit super snugly in the hole, but the nut does. If the nut is tightened enough, it doesn't end up being an issue in the end.

Good luck on the conversion. I hope you can get the 650b going.

RD said...

like you said to have 650b just because it a bit silly. 700c would give you more choices i don't think that would matter that much for the purposes of your bike.

munsoned said...

My personal thoughts are: ABANDON SHIP! ABANDON SHIP!!

I almost piped up when you mentioned you were going from a 27" frame to 650B. It just didn't sound right to me. The brake distance would be just too much. But I figured since you had the guy from 13th St bike shop helping you out, he must have done it before.

I say, have the shop guy trade your 650B wheels for some regular 700C wheels since he advised you in the wrong direction. That way, either brake will work and you can choose and number of tires in all different widths.

To me, 650B wheels were created to change a 700C frame into a "country bike" like you mentioned. So, 700C wheels should be able to provide the same result for a 27" frame. I even have some 42C tires for you if you want. Not sure if they'd fit your frame with 700C wheels, but the offer's there.

Scott Redd said...

Thanks Rafal, Steve and Munson:

I'm inclined to shelve the 650B project for the time being. When I fitted my hybrid's 700C wheels onto the Schwinn, they seemed to work. The only thing that kept me from riding the Schwinn in that configuration was that the brand new chain didn't like the worn cogs (about 3k miles on them) and skipped like crazy. Or maybe it's the 7-speed chain on an 8-speed cog set causing a problem.

The 35m tires didn't afford much room between the chainstays, so I don't know if I could take anything much larger. However, there may be enough clearance left to still attach fenders; a must with a "country bike".

I'll make it clear that Mike at the Recycle Bike Shop didn't advise me improperly on this... it's all my planning. He just helped me get the wheels and trued them up for me and stretched my frame.

I'll either hold on to the wheelset for when some other old frame comes along, or as Munson suggested, trade them with someone for some 700C, or just outright sell them.

In googling for things like "Schwinn Le Tour" and "650B" I only came across one mention of it being successful. Perhaps my blog posts on this will help advise someone who tries it in the future.

On another note, I successfully overhauled the threadless headset on the Specilized Tricross this evening. Yay! Rafal encouraged me to try to overhaul it myself, and various web pages gave me some pretty good descriptions, instructions, photographs and even some videos.

The steering had gotten super stiff since last week. It was so bad that I had to force the bars to turn. I could turn the bike sideways and the fork would not turn on its own.

When I took it apart, it was even kind of gritty inside. There was caked up dirt (or maybe dried lubricant?) on the top of the star nut. When I got to the bearings and races, they were really gunked up. After a good cleaning in WD40, I think I observed that the bearings are a little mashed. I think I need to replace them. It also seems like the top races and cup aren't as smooth as they should be. I think the cups are integrated into the frame, so there's probably nothing I can do about that.

I packed everything back in with lots of grease, hopeully assembling all the various parts back in the right order and direction. Now the steering is pretty darn smooth, though it still seems to me like it's little rougher than it should be. Again, I probably need to replace the ball bearings and races, but I think if I keep an eye on it and service when necessary, I can get some years out of this frame.

RD said...

if you bearings are worn really really bad you might as well replace the headset all together it's not that much and you will notice difference.... but if you are able to turn without any noise i would say use until you can't use it anymore. the install process is not that bad you just need some elbow grease that's all.

your skipping is actually combination of wrong chain and cassette... cough cough single speed

erik said...

bummer, gotta measure in advance.

it's funny that people are ripping on you for trying something far more sane and well-budgeted than most of the bullshit that goes on in the racing circles.

650B is totally sensical, and you'd be able to rid a very large tire indeed with it (like IRC knobbies), but on a frame like this with wider clearances to begin with on a 27" it seems 700c is your best bet.

were I you, I would keep the wheels and brakes and look for a better 650 conversion candidate frame from the vintage realms. you can get a stripped one even, and just move it all over (i know, now people are really going to rip)--the schwinn is fine but it wasn't going to be anything amazing in terms of design to begin with.

either that or get the brake drop bolts, they are fine--obviously though a 700c tire is going to have plenty of clearance to begin with there.

wish i could have helped you out, or do so now, but i'm packing.

best of luck.

erik said...

you could try this if you wanted to be kooky;

labratty said...

Would it be possible to make a drop plate for each brake pad? From the maximum drop to another half inch or whatever lower. They will not experience the same twisting force the drop plate/caliper would on the small round cross member.
It might be that the 556 are too long to fit a drop plate inder and you would want a shorter drop to make the idea work.
The drop plate could have 3 bolts in it, 2 in the slot on the caliper to resist twisting and the 3rd at the bottom to put the brake pad in.

Scott Redd said...

Hi Labratty:

Thanks for the idea. That's an interesting alternative to extending the calipers.

Just last week I converted the Le Tour to a single speed. I've still got the 650B wheelset, so I may yet come across a frame to do this with.