Tuesday, July 5, 2011

Speed pram-related issues

The above picture is included here to prove that tinkering and bicycle-related stuff is not the main point about being a dad, even though I realize I might make it seem that way.

Projects are rarely really finished around here. That's me above, you can see part of Frog's forehead, she's inside the box. I may look smug but really, I'm obsessing about the brakes.

Even when I hooked up my dogs to this contraption in the forest I had a pretty relaxed attitude to the braking power at my disposal. Sooner or later, I knew, we would start going uphill and slow down. Freighting a baby in traffic is a different story.

I have a Shimano coaster brake on the rear wheel, and hub brakes on the front wheels. They look like Sturmey-Archers, but I'm not sure.

I am unhappy about the way the wires are connected to the brake arms on the hubs. Above is a picture taken from the underside of the Christiania's box. You can see the wire beeing fed out of a threaded tube at an awkward angle. Once I change the cables and the cable housing, the cable is still going to keep on scraping that tube. Something has to be done here, but I'm not quite sure what.

There's not a lot of information on drum brakes out there. For example, the wire tension on all drum brakes I've seen can be adjusted close to the hub (that's the point of the nut around the threaded tube in the picture above), but does it have to be that way? (My 1948 bike has the same system.) Are adjuster barrels on the handles completely out of the question?

I found some interesting information here, this guy even recommends opening up the hubs, something most books on bicycle maintenance strongly advise against. (Which in itself makes it tempting for me to try.)

I needed to change the gear cable and of course, of course, the new cable was of "normal" length, in other words far too short for all that weird cable routing a front-loading trike needs. So that's the thumb shifter down on the right hand side of the box (above), instead of on the handle bar. Not very practical, but it's not there for ever.

5 comments:

Andy in Germany said...

I'm going to sound a complete bike nerd here, but there we go:

Our Bakfiets has Tektro Brake handles and Nexus hubs, and I can't say I'm wild about the performance either, but they're okay. The Tektro brakes have adjuster barrels and they do make a difference to the amount of pull you get out of the brake, sometimes to the extent of causing drag, especially on the front brake where it's a very fine margin between having the brake work and having a sort of permanent handbrake.

The length of cables doesn't help, of course. I have to get Tandem cables for most Bakfiets and Xtracycle-related cabling.

It doesn't seem to offer many options for rerouting the cable. How far does the brake arm move back when you pull the cable? Perhaps you could add a pivoty thing (technical term) between the aduster and the brake arm to reduce wear on the cable? or a router rather like the little metal right-angle found on V-brakes?

(The above is based on guesswork and an almost total lack of experience in drum brakes)

Northmark said...

The brake levers feel tight and nice, but don't really lead to a whole lot of braking. The Christiania has been stored outdoors all its life, and I haven't changed the cables for ages. I think I'll change the levers to ones with adjusting barrels and locks, change the cables and also open up the brakes. Also, one of the brake arms seems stuck.

This guy also added a retrofit v-brake on the rear wheel of his trike. If I did that too, I'd have four brakes, can't get too many

fatbob29r said...

+ 1 on the Tandem cables... yes it's a PITA to have to order them, but they're typically stronger since they're designed for more weight.

As far as the brake and routing, you're in the right direction, old cables/housing will cause some friction and the addition of the strange angle of cable departure isn't helping. Might try one of these

http://problemsolversbike.com/products/travel_agents/

to help reduce drag/friction.

Finally, you should be able to add a barrel adjuster at either end for quick adjustments at the lever or brake arm.

Cheers

Eileen A. Brodie said...

Hello Northmark!
If faced with this at my bench, I would drill a new hole aft of the existing one that now holds the barrel adjuster fixture. A round hole, that could then be filed square to accept the square post. (Looks like there is room on the steel arm to do this.) For this new hole I would make it so the post is now held at an angle that improves the path of the cable-to-brake actuating arm. What I can't see is whether the post is bolted on, or peened or welded. I hope it is threaded so you can do this fix easily! If not, you could drill a hole into the square post after hacksawing the back weldment or peened-over metal from it. (leave the square shoulder though) then tap it to accept a bolt. Would need a "bottom" type tap, not a pointed through-type. Make sure to use a lockwasher.

Eileen A. Brodie said...

Hello Northmark!
If faced with this at my bench, I would drill a new hole aft of the existing one that now holds the barrel adjuster fixture. A round hole, that could then be filed square to accept the square post. (Looks like there is room on the steel arm to do this.) For this new hole I would make it so the post is now held at an angle that improves the path of the cable-to-brake actuating arm. What I can't see is whether the post is bolted on, or peened or welded. I hope it is threaded so you can do this fix easily! If not, you could drill a hole into the square post after hacksawing the back weldment or peened-over metal from it. (leave the square shoulder though) then tap it to accept a bolt. Would need a "bottom" type tap, not a pointed through-type. Make sure to use a lockwasher.