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-   -   700c to 26" conversion (https://www.bikeforums.net/bicycle-mechanics/917968-700c-26-conversion.html)

likebike23 10-16-13 07:00 AM


Originally Posted by corwin1968 (Post 16164624)
Are the Tektros that likebike23 posted a link to BMX calipers? What type of levers will work with them? I have plenty of traditional cantilever MTB brake levers so hopefully those work.

The brakes linked to are known as caliper brakes. They are made to work with cruiser bikes as they have a long reach and room for wide tires. BMX and road brakes in this style are also caliper brakes. Calling a caliper brake a "road/BMX/or cruiser" brake is just a way to make it easier to choose which caliper you need based on the application. What's important when choosing which caliper you need is the reach, whether they're nutted or recessed, and tire clearance. They all will work with MTB levers designed for cantilevers or road levers.

LesterOfPuppets 10-16-13 07:57 AM

Guess those are made for beach cruisers. The Headbadge warns that they have a minimum rim width spec of 38mm.

Looks like Tektro 384 don't have the reach you need. Not sure what I'd go with.

corwin1968 10-16-13 09:57 AM


Originally Posted by LesterOfPuppets (Post 16164896)
Guess those are made for beach cruisers. The Headbadge warns that they have a minimum rim width spec of 38mm.

Looks like Tektro 384 don't have the reach you need. Not sure what I'd go with.

Thanks for checking on that and giving me a heads up! I'm only familiar with 700c rims and have no idea how wide typical 559 rims run, but now I know it's not 38mm :(

corwin1968 10-16-13 10:00 AM

There may not be a real solution short of physically modifying something. I may just pick up some cheap 26" slick tires to replace the knobbies and spend some time riding it san brakes. I've been doing that for the last couple of days, just riding up and down the street to get a feel for the bike. I did find a 1988 Bridgestone MB-5, which has geometry closer to what I like than most MTB's, but it's $100 and has one of those funky rear brakes that I know nothing about.

likebike23 10-16-13 11:04 AM


Originally Posted by LesterOfPuppets (Post 16164896)
Guess those are made for beach cruisers. The Headbadge warns that they have a minimum rim width spec of 38mm.

Looks like Tektro 384 don't have the reach you need. Not sure what I'd go with.

I don't think that's a deal breaker at all. The headbadge review mentions that you could put different threaded pads (v-brake type) with spacers between the pad and arm to take up the space. I would try that before I would ride around with no brakes. These are cheap for 2 pairs and probably better than the stock pads:http://www.niagaracycle.com/categori...e-pads-regular. Not trying to be disagreeable, but I really think that figuring out the brakes is of paramount importance to any bike project's success.

corwin1968 10-16-13 08:18 PM


Originally Posted by likebike23 (Post 16165588)
I don't think that's a deal breaker at all. The headbadge review mentions that you could put different threaded pads (v-brake type) with spacers between the pad and arm to take up the space. I would try that before I would ride around with no brakes. These are cheap for 2 pairs and probably better than the stock pads:http://www.niagaracycle.com/categori...e-pads-regular. Not trying to be disagreeable, but I really think that figuring out the brakes is of paramount importance to any bike project's success.

I agree. I won't be doing much riding on it until I at least get a good front brake or decent front/back brakes on it.

surreal 10-16-13 08:38 PM


Originally Posted by corwin1968 (Post 16165375)
There may not be a real solution short of physically modifying something. I may just pick up some cheap 26" slick tires to replace the knobbies and spend some time riding it san brakes. I've been doing that for the last couple of days, just riding up and down the street to get a feel for the bike. I did find a 1988 Bridgestone MB-5, which has geometry closer to what I like than most MTB's, but it's $100 and has one of those funky rear brakes that I know nothing about.

You wanna know about that funky rear brake? It's a U-Brake, and it's the most awesome brake ever. The mb-5 may've been the second-to-crumbiest Bridgestone MTB ever, but it's still got rockin' geometry. If it has a chainstay mounted u-brake, that'd make it a 1988 model. These have about as short a wheelbase as horizontal-toptube mtbs ever had, but it's still gotta be at least 420mm at the chainstays.

I tried to not get into the whole bulldog/880-style "bmx" caliper discussion, but those are the worst brakes ever. With some fiddling, you can set them up to stop a wheel, but they'll never perform very well, and the feel at the lever is utterly disgusting. Avoid. You can't be sure they'd even do the trick for this application, anyway, unless you do some careful measurements. Get a coaster or a drum or something... or get some lockjaws by mr. tick. Which is what you'd really need for this l'il experiment, but if $100 seems like a lot for a cool mtb like an mb-5, then $75 for some bolt-on canti bosses will probably give you fits. :twitchy::troll:

corwin1968 10-17-13 05:25 AM


Originally Posted by surreal (Post 16167189)
You wanna know about that funky rear brake? It's a U-Brake, and it's the most awesome brake ever. The mb-5 may've been the second-to-crumbiest Bridgestone MTB ever, but it's still got rockin' geometry. If it has a chainstay mounted u-brake, that'd make it a 1988 model. These have about as short a wheelbase as horizontal-toptube mtbs ever had, but it's still gotta be at least 420mm at the chainstays.

I tried to not get into the whole bulldog/880-style "bmx" caliper discussion, but those are the worst brakes ever. With some fiddling, you can set them up to stop a wheel, but they'll never perform very well, and the feel at the lever is utterly disgusting. Avoid. You can't be sure they'd even do the trick for this application, anyway, unless you do some careful measurements. Get a coaster or a drum or something... or get some lockjaws by mr. tick. Which is what you'd really need for this l'il experiment, but if $100 seems like a lot for a cool mtb like an mb-5, then $75 for some bolt-on canti bosses will probably give you fits. :twitchy::troll:

It's not so much the $100 as it is the concept of bringing ANOTHER bicycle home. The couch isn't very comfortable to sleep on. ;)

If I hadn't already bought the 820 I probably would buy the MB-5 but at this point my obsession is moving towards modern MTB/Tourers like a Surly Troll or Ogre. I rode Trek 730's from 1995 to 2007 and then from 2011-2013 and after riding my 26" conversion and the 820, my 700c Devil feels "twitchy" with it's 60 mm of trail. I bought it specifically to experience a bike with road bike trail but I think I actually prefer a higher amount. I know I'll comfortably ride my 730 with 74mm trail (700 version) in off-road areas where I'm VERY uncomfortable riding the Devil.....and that's with the same wheels and tires on each bike.

tcs 10-17-13 05:35 AM

Another back brake that would work. Might double the cost of the project, though!

Retro Grouch 10-17-13 06:50 AM


Originally Posted by corwin1968 (Post 16165375)
There may not be a real solution short of physically modifying something. I may just pick up some cheap 26" slick tires to replace the knobbies and spend some time riding it san brakes. I've been doing that for the last couple of days, just riding up and down the street to get a feel for the bike. I did find a 1988 Bridgestone MB-5, which has geometry closer to what I like than most MTB's, but it's $100 and has one of those funky rear brakes that I know nothing about.

Under the chainstay U-brake? You'll use your full vocabulary and maybe make up a few new words the first time you try adjusting one of those.

LesterOfPuppets 10-17-13 06:53 AM

I love the way springs are adjusted on U-Brakes.

Attaching yokes and straddle cables on them has been nightmarish for me on many occasions, however.

likebike23 10-17-13 07:00 AM

@corwin1968- If you want to experiment and have fun with your project, then go for it. Don't listen to the naysayers, it's your time and money, sometimes thinking outside the box is the best way to learn. Sure it might be a disaster, so what, only you can decide that. As for the bulldog brake being the worst ever as Surreal said, that may be true. The bulldog however, is not the same design as the Tektro. The Tektro is a dual pivot design, where the bulldog is a single pivot. The cost to try the Tekto is low (~$30), the challenges are not difficult to overcome, and they are well rated on Amazon. If you decide to go that route, just make sure that you get the brake with the proper reach for the bike. There is a longer reach brake available also:http://www.niagaracycle.com/categori...8-116mm-silver. Good luck and keep us posted. Mike

LesterOfPuppets 10-17-13 07:08 AM

There's always the drop bolt option, too. Could come in handy if you wanna go with some brakes with 80mm reach but need a bit more to get your 99mm reach.

http://sheldonbrown.com/home-drop.html

Retro Grouch 10-17-13 07:09 AM


Originally Posted by likebike23 (Post 16167878)
@corwin1968- If you want to experiment and have fun with your project, then go for it. Don't listen to the naysayers, it's your time and money, sometimes thinking outside the box is the best way to learn. Sure it might be a disaster, so what, only you can decide that. As for the bulldog brake being the worst ever as Surreal said, that may be true. The bulldog however, is not the same design as the Tektro. The Tektro is a dual pivot design, where the bulldog is a single pivot. The cost to try the Tekto is low (~$30), the challenges are not difficult to overcome, and they are well rated on Amazon. If you decide to go that route, just make sure that you get the brake with the proper reach for the bike. There is a longer reach brake available also:http://www.niagaracycle.com/categori...8-116mm-silver. Good luck and keep us posted. Mike

+1. At least half the fun of a project like this is trying different things to see what works and what doesn't. "Every mistake only makes you smarter."

likebike23 10-17-13 07:17 AM


Originally Posted by Retro Grouch (Post 16167861)
Under the chainstay U-brake? You'll use your full vocabulary and maybe make up a few new words the first time you try adjusting one of those.


Originally Posted by LesterOfPuppets (Post 16167867)
I love the way springs are adjusted on U-Brakes.

Attaching yokes and straddle cables on them has been nightmarish for me on many occasions, however.

I also like the spring adjustment and feel of U-brakes. I've found if you get the cabling done when their is no spring tension that it is easier. I back out the lever barrel adjuster, set the yoke position, and then set the straddle position so that the pads are lightly contacting the rim. You can then compress the housing/adjust the lever barrel adjuster to get the proper pad clearance and tighten down/adjust the springs. Other than the fact that they are in a tough position on the bike, I've had good luck using that method.

dbg 10-17-13 08:50 AM

1 Attachment(s)
Hmmm. The chainstay u-brakes on my restored 88 Trek 850 are wonderful. Best stopping power of any brake I own and the lever feel and pull is great.

Wonderrful bike BTW. Early mtb with mostly road geometry (130 rear drop, 68mm BB, road Q) but longer stays and 26" wheels.

surreal 10-17-13 09:18 AM

I can't say enough good things about u-brakes. Aside from interfering with the installation of a centerstand or kickstand, I think these are the best option for the practical touring cyclist. Good, strong braking that works well with drop bar levers and canti-levers alike. Tucked out of the way; no chance of heel-strike or interference with panniers or racks. And it just looks retro-trick. It somehow combines the aesthetic of rodbrakes with the radness of bmx, and comes up with a whole new recipe of brakin' goodness.

corwin1968 10-17-13 02:56 PM

1 Attachment(s)

Originally Posted by LesterOfPuppets (Post 16167890)
There's always the drop bolt option, too. Could come in handy if you wanna go with some brakes with 80mm reach but need a bit more to get your 99mm reach.

http://sheldonbrown.com/home-drop.html

This might be a fun project, in and of itself. I might keep an eye out for some inexpensive caliper brakes to use. Any suggestions that won't break the bank? Also, will MTB size tires fit under caliper brakes?

http://bikeforums.net/attachment.php...hmentid=346494

bobotech 10-17-13 03:34 PM

Since you are doing all the modifying, have you thought about getting disc brake tabs welded to the frame? I'm not sure how much that would cost but then you could use a set of disc brakes and any size rim you want. The only catch would be is that you have hubs that are disc brake compatible but you can pretty much lace in any hub you want to a set of rims.

Then you could play around and try all sorts of different rims and not worry about the brakes.

corwin1968 10-17-13 05:29 PM


Originally Posted by bobotech (Post 16169288)
Since you are doing all the modifying, have you thought about getting disc brake tabs welded to the frame? I'm not sure how much that would cost but then you could use a set of disc brakes and any size rim you want. The only catch would be is that you have hubs that are disc brake compatible but you can pretty much lace in any hub you want to a set of rims.

Then you could play around and try all sorts of different rims and not worry about the brakes.

The thought had crossed my mind briefly but I assume that would be much more involved than moving the canti-studs and I would have to buy the disc brakes as well as have new wheels built so it would get very expensive, very fast.

surreal 10-17-13 05:35 PM

Smart money is on drums, as TCS and myself both mentioned up-thread. No frame mods at all; if you get the x-rdf for thread-on freewheel, you can run from 110mm to 135mm OLD, 1 thru 7 speeds (possibly an 8 speed, but i'm not sure there's room for all that) and plays nice with vertical dropouts if you go 5+ speeds....or run a tensioner with ss.....

$85 plus a wheelbuild; i'd go 2x on a 26" wheel....

noglider 10-17-13 09:23 PM

I don't think it's a dumb idea.

fietsbob 10-17-13 10:42 PM

700c to 650B is done more commonly , difference is less. too..

corwin1968 10-18-13 11:43 AM

Other than the U-brake, is there anything else on a 1988 Bridgestone MB-5 that would problematic as far as running modern components on it? Is the BB shell the same as now? After squinting enough to read the geometry in the 1988 catalog on Sheldon Brown's website, I'm seriously considering buying it. It appears to pretty much be a heavy 26" wheel road bike.

surreal 10-18-13 11:56 AM


Originally Posted by corwin1968 (Post 16171618)
Other than the U-brake, is there anything else on a 1988 Bridgestone MB-5 that would problematic as far as running modern components on it? Is the BB shell the same as now? After squinting enough to read the geometry in the 1988 catalog on Sheldon Brown's website, I'm seriously considering buying it. It appears to pretty much be a heavy 26" wheel road bike.

Feh. You can run a modern u-brake on it, if u like. Any current-production u-brake will work, although I'd just put new pads on the stock one, if I were you.

BB shell is BSC, standard thread, probably 68mm. The dropouts are vertical and by '88, more than likely 130mm--outside chance that it's 126, but even my 87 b-stone 300 roadbike had 128mm dropouts, in case I wanted to build it up 8speed. 1" threaded headset, prolly JIS but late 80s were weird for mtbs, with some Japanese makers going with 26.4mm crown races.

Once you get that u-brake how you want it, you'll regard rear cantis on mtbs with something akin to disgust.


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