Bicycle Mechanics - Backwards Cantilever Bosses on Raleigh Portage?
Bikeforums.net is a forum about nothing but bikes. Our community can help you find information about hard-to-find and localized information like bicycle tours, specialties like where in your area to have your recumbent bike serviced, or what are the best bicycle tires and seats for the activities you use your bike for.
06-09-09, 05:59 PM
Please help much revered elders!
I have recently purchased a 1985 Raleigh Portage which has it's fair share of weird frame characteristics. The most frustrating thus far has been the cantilever bosses. The holes on most bosses for the spring to interface with are on the inside of the actual cantilever post, but on this bike the spring interface holes are on the outside of the post.
Because the tension adjustment holes are on the opposite side of the post from a normal brake boss all the springs I have tried result in extremely high tension levels when the brakes are installed. That is, if I can actually manage to install the calipers. The only way I have found to install a functioning caliper is to install without the plastic dust cap which protects the spring and forces the spring to remain inside the caliper itself. This lets the excessive spring tension bow out of the caliper without inevitably breaking the plastic cap.
I purchased the frame and wheels with no components, but have purchased the original Deore XT calipers for the restoration. I also have a slightly newer XT caliper that seems to work a little better, but I am not really happy with either system.
Has anybody seen this one? Did somebody make a caliper designed for this?
06-09-09, 07:54 PM
My daughter had a Technium mountain bike from about that era that had brake studs like that.
I was never successful in finding brake parts that satisfied me. Eventually I solved the problem by cutting off the canty studs and converting the bike into a fixed gear.
06-09-09, 08:19 PM
practical joke imo.
06-09-09, 08:25 PM
My Bridgestone MB-3 uses DiaCompe 986 canti's that use a anchor for the spring that doesn't actually use the holes in the frame boss. The tension is adjusted by turning the anchor with a cone wrench of the proper size and then tightening down the cap screw that holds the caliper on. 986's would work great for your Raleigh Portage. Plus, they stop good too. There's often some on ebay.
The anchor is the silver piece behind the black plastic cover in the photo. See red line. Sorry for the vague photo.
06-09-09, 08:29 PM
I have a 1987 model Trek 800 with the same issue. I purchased a set of NOS Dia Comp 986 brakes. They do not use the spring holes and I have had very good luck with them. A local frame builder quoted me $60 to cut the studs off and replace them with the now normal posts and spring holes but the 986's did the trick for me.
06-09-09, 10:01 PM
I’m the guy that sold that frame to you. If you did a search in this forum, you would probably come up with my old posts from a couple of years ago seeking info on the same issue. When I got that bike, it came with the original brakes. But, not realizing that it was such a queer set up, I sold them off on CL because I was intending to use Paul touring cantis on there. Went to mount the Paul’s and that’s when it hit me what I was dealing with. Did my homework, including some helpful info from other forum members here, and learned that I needed those XT’s (the ones I gave you), so I ran over to Sibley Bike Depot and dug through their bins to find those. Those XT’s work because you can swap the springs from one side to the other and anchor the return springs to the inside and still have the springs wind the way you need them to. If you’re not happy with the ones I gave you, you’re probably looking on eBay for the “Deer Head” group or other early ‘80’s vintage XT. You could have the bosses re-brazed -- which I never wanted to do because the frame was in such good shape and I didn’t want to destroy the original paint and decals -- but even if you got the bosses reversed, you are still dealing with the fact that the studs are a lot closer together than modern cantis are spaced for. It definitely was one of the unique challenges of that frame.
Edit: I was able to get them functioning fine with the dust caps in place.
06-21-09, 08:41 PM
Thanks a lot for your help! I've tried the original Deerhead calipers with no success which seriously confused me. There is no way I'd re-braze the bosses, this frame is way too pretty.
I will be giving the Dia-Compe 986 cantis a try, hopefully it will work out!
Dia-Compe 987s will also work.
06-22-09, 12:24 PM
I don't think that the DiaCompe's will work. You really have two issues with those brakes: (1) the reversed bosses; and (2) the much narrower spacing of the bosses on the front.
As to problem #1, I mentioned that I already tried the Paul touring cantilevers, which are similar in design to the DiaCompe's in the sense that they don't use the bosses to anchor the return spring. The return spring tension on the Paul brakes is adjusted in the same way as it is on the DiaCompe's. That will solve Problem #1, and will give you a working rear brake. In fact, the Paul's worked fine on the rear, and I believe that the DiaCompe's will also.
The front is where the real problem lies. Those front bosses are spaced about 2cm closer together than most anything you will find. So, for the fronts, while the DiaCompe's will solve your first problem of not having to rely on the reversed bosses to anchor your spring, the second problem will result in the brake shoes not hitting the rims properly.
The few unique brake designs out there that can solve problem #1 cannot solve problem #2, and vice versa.
If you still have my e-mail or phone from our initial transaction, get in touch and I will try to help you - otherwise, pm me with your contact info through this forum. I did have those XT's that I gave you functioning perfectly with the dust caps in place.
07-13-09, 10:00 PM
Saw the bike a second time today outside Seward Co-op. You told me you had gotten the DiaCompe's, but that's not what I saw on there. Did they work? Were those a different set of XT's than what I had given you? Just curious after all the bs I went through.
07-20-09, 08:01 PM
Yeah, life and summer have gotten ahead of my mechanics as of late!
I've installed the rear DiaCompe 986's today and they feel great. Really easy setup, and it certainly appears to have solved problem #1. Those are the same XT's you included with the bike, with the recommended dremmel tool modifications performed to the internal tension washer.
I hope to make an attempt at the front cantis this week, if I don't take it camping that is : )
Out of curiosity, do you still have the touch-up paint pen for this bike?
Your friendly neighborhood produce worker.
07-21-09, 10:54 AM
I probably still have the pen, but it may be dried out by now. Not sure how fast those things dry up once the seal is pierced. I'll try to dig it up and drop it by the next time I'm at Seward. I've also been giving some thought to selling off the Velocity Synergy rims that I had custom-drilled for that bike. I like them and will probably use 650b Synergy's on a bike in the future, but now that I don't have that bike anymore, I don't need to be locked in to that mismatched 40h rear/36h front. Let me know if you might be interested in them -- I always figured that I would rebuild the wheels with these rims, which have a hook to them, so that I could expand my tire choices.
07-26-09, 05:18 AM
Thanks a lot for the paint! I'll give some thought to the rims, thanks for the offer! Did you ever get the custom frame from your friend? I'd like to check it out next time you're in if you did!
Powered by vBulletin® Version 4.1.12 Copyright © 2013 vBulletin Solutions, Inc. All rights reserved.