Bicycle Mechanics - Help with disc brake conversion?

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View Full Version : Help with disc brake conversion?


JLTinsley
08-18-11, 09:51 AM
So I want to convert this bike, which currently is a single speed with a coaster brake, to a bike with an internal gear hub (7 or 8 speed) and disc brakes. Here are the specs:

Frame: HandCrafted 4130 Chromoly Steel and 1x H2O boss, Rear rack mounts, rear fender mounts
Fork: Dura Forte Chromoly Unicrown with Fender Mounts, 1" threaded steerer
Stem: Aluminum alloy Threaded, 1" quill
Handlebar: Aluminum alloy Comfort Swept-back
Derailleurs: n/a
Shifters: n/a
Brakes: Rear Coaster Brake (pedal backwards for braking)
Hubs Front: Aluminum ALLOY SILVER NUTTED
R/HUB: SHIMANO COASTER CBE110
Rims: DA17, Aluminum ALLOY SILVER, 700c with 36 holes
14G STAINLESS Spokes W/BRASS NIPPLES
Crank LSC 44T Chainring, 170MM Aluminum ALLOY SILVER Arms
Cartridge Bearing Bottom bracket
Tires: Kenda 700x32C BLACK wall

And because pictures sometimes help:

http://www.bikesdirect.com/products/windsor/images/essex_dlx_pink_2100.jpg

My question is, what all will I need to do to convert this bike to disc brakes? I could deal with just the front being disc and the back being either a drum brake or rim, if the rear conversion would prove really difficult/expensive, but would prefer both front and back being disc.

What I think I know so far is: For the front, I will need a disc compatible fork (with a 1" threaded steerer??), disc compatible hub, and of course, the brake components themselves. However, I don't think 1" threaded steerer forks for disc exist (I can't find any, anyway) so what would I need to do to make this work? But a new stem, headset, what size, etc?

For the back, I thought I just needed a disc compatible hub (I was going to get the Sturmey Archer internal 8 speed) and the brake system. However, seeing something on the interwebz made me think I might need disc brake tabs on the rear dropouts/seat-stay/chain-stay intersection too. Is that true? Will it even be possible to use disc brakes on the back without being exorbitantly expensive? If it would be a huge hassle and cost me an arm and a leg, I'll just do a drum or rim brake in the back...so how would I convert from a coaster brake to that?

Thank you all for your help!


HillRider
08-18-11, 10:06 AM
The cost of the conversion will be prohibitive.

A new fork, a new front hub, the brakes themselves and new levers at an absolute minimum for front brakes only and that assums you can find a threaded fork with mounting tabs. More likely you will need a new threadless fork, headset, stem, hub and brakes and levers just to have a front brake.

Your rear stays aren't going to be rigid enough to properly support mounting tabs but they could be welded on if you insist. Of course a repaint will be needed to cover the heat damaged area. I believe there are clamp-on tab but i have no idea if they work. Then add the cost of the new disc compatible rear wheel with the IGH, the brakes themselves, etc.

By the time you are done, you will have spent much more than the cost of a decent complete bike already equipped the way you want. Either buy a properly equipped bike and keep this one as a second bike or sell it to help finance the right bike.

fietsbob
08-18-11, 10:14 AM
Thanks for supplying the picture..
+1, above.. The frame lacks the required disc brake caliper mounts.
you should go shopping for a bike that does.

Or instead, consider the re building the wheels around Drum Brake hubs.

Sturmey Archer offers a nice 3 and 5 speed drum brake hub ,
Sram offers a drum 7 speed.

Because of the ratios internally, a Sturmey 8 speed, needs a tiny chainring
with a larger wheel.


JLTinsley
08-18-11, 10:20 AM
Hmm. Ok. Seems like it would just create too much trouble. In that case, what would I need to do to put cantilever brakes on front and rear? I see a little screw on the top of the fork...is that a place to mount a rim brake?

Kayce
08-18-11, 10:25 AM
Cantis would be the same problems, only much harder to find a fork. They require posts on the fork and seat stays to mount. The hole in the fork is to mount the fender on, and it may be able to be used for mounting a standard rim brake. But with the fenders it may be hard to fit one.

clasher
08-18-11, 10:28 AM
Canits would be just as much work as disc brakes. If it needs to be this frame and an IGH I think drum brakes are the only reasonable way to go about it. I imagine long reach caliper brakes would work on this bike if you want to improve the braking.

HillRider
08-18-11, 10:29 AM
You may be able to mount caliper brakes if you can find ones with the proper "reach". The hole in the fork crown can be used to mount the front one and there should be a similar hole in the brake bridge in the seat stays above the rear wheel. This would be, by far, the cheapest and least damaging option.

JLTinsley
08-18-11, 11:00 AM
Thank you guys for all your help! I think I'll just do a caliper brake in front (I've found some long reach ones that should do the trick) and either get an IGH with a drum brake or do a caliper in the back as well (you can't see it well from the small picture, but there is another hole on the seat stay, like @HillRider said; here is a larger pic to see it better: http://www.bikesdirect.com/products/windsor/images/essex_dlx_pink_2100.jpg).

My question then is, would you guys recommend the drum brake or caliper more? The drum provides the advantage of all-weather braking, no worries about rain and sludge and the like; however, I think repairs and maintenance would be more of a hassle...what is your opinion? Drum or caliper in the rear?

RB1-luvr
08-18-11, 11:08 AM
if you end up selling that wheelset, I would buy them from you. I convert bikes to single speeds, and I frequently need coaster brake 700c wheelsets .

JLTinsley
08-18-11, 11:15 AM
@RB1-luvr If I do I'll definitely let you know!

RB1-luvr
08-18-11, 11:28 AM
cool, thanks.

fietsbob
08-18-11, 12:35 PM
what would I need to do to put cantilever brakes on front and rear? I see a little screw on the top of the fork...is that a place to mount a rim brake?

for BMX there are bolt on adapters that include the Bosses that could mount a brake ,
of that type.. V or cantilever, But..

But I agree finding a suitable caliper brake will be much more straightforward.

benefit of Drum brakes is that they stop the same in any weather.

A rim brake pad has to get thru the wet on the rim, & dry it,
to get enough friction.
wheel rim rolls down to the wet street again, with every rotation.

HillRider
08-18-11, 07:52 PM
benefit of Drum brakes is that they stop the same in any weather.
Correct. however, the down side is cost, weight and more complex wheel removal and replacement for flat repair (just like a coaster brake or IGH).