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700c Hybrid Fork In Vintage Road Bike Frame? Crown Race?

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700c Hybrid Fork In Vintage Road Bike Frame? Crown Race?

Old 01-01-16, 09:30 PM
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Primitive Don
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700c Hybrid Fork In Vintage Road Bike Frame? Crown Race?

I searched around and found some information, but I still have a couple of questions.

I have an '83 Schwinn Traveler, made by Giant in Taiwan. I run 700c wheels in it and have used Dia Compe centerpulls because the pads reach the rims and it brakes well.

I am modifying this into a gravel grinder bike to be able to ride off-road with wider tires, sort of a poor man's cyclocross bike. I would like to have better braking going downhill, like the V-brakes on my mountain bike, at least in front.

I have a spare V-brake, and I would like to put on a replacement 700c hybrid fork with canti bosses for the brake. When I look around, I see some with 27.0 mm crown race, some with 26.4 mm.

Would that bike have come with a 27.0 mm crown race or 26.4 mm? Unfortunately I don't have a way to measure with that accuracy, and I understand that is a tight or press fit.

I read on this forum and others that folks have used 700c forks with vintage road frames. Is there any reason that is not a good idea?
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Old 01-01-16, 11:07 PM
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Taiwanese bikes of that era could be either. It really depends on what the client specified. At some point you need to remove either the crown race or either head tube cup. Then measure and confirm whether it's JIS or ISO (Campy) standard.

If you want an educated guess, I'd say ISO, but only give you 7:3 odds on it.
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Old 01-01-16, 11:26 PM
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Agree with Francis. Most mid/low cost Asian bikes use 27.0 races. But as soon as one spends money based on an assumption... Andy.
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Old 01-01-16, 11:40 PM
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Fair enough, point well taken. I'll see if I can't scare up some good quality digital calipers capable of that level of accuracy.

Thank you, gentlemen!
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Old 01-02-16, 12:18 AM
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The V brakes won't be any better than the centerpulls, assuming good pads and setup on each. Either one will be able to throw you over the handlebars. Once a front brake can do that, it really can't get too much better. Further improvement in braking requires technique, shifting your weight rearward.
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Old 01-02-16, 07:54 AM
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Originally Posted by jyl View Post
The V brakes won't be any better than the centerpulls, assuming good pads and setup on each. Either one will be able to throw you over the handlebars. Once a front brake can do that, it really can't get too much better. Further improvement in braking requires technique, shifting your weight rearward.
You think so? Wanting my road bike to stop as well going downhill as my mountain bike, particularly during wet and muddy conditions, is the impetus for this project.

I appreciate your response.
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Old 01-02-16, 07:57 AM
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Originally Posted by jyl View Post
The V brakes won't be any better than the centerpulls, assuming good pads and setup on each. Either one will be able to throw you over the handlebars. Once a front brake can do that, it really can't get too much better. Further improvement in braking requires technique, shifting your weight rearward.
Well, if the OP's current brake is an old Dia Compe centerpull, it can indeed lock the front wheel but the hand effort needed to do so may be much higher than the OP is comfortable with so a more "powerful" brake is desired. Replacing it with a modern dual pivot sidepull (probably "long reach") is probably cheaper.
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Old 01-02-16, 08:16 AM
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You will probably need a new brake lever for a V-brake or add a travel agent to adapt the short pull lever to the long pull V-brake.
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Old 01-02-16, 08:23 AM
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I have a donor bike with a levers that goes with the brake. I'm already using flat bars.
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Old 01-02-16, 09:31 AM
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Originally Posted by Primitive Don View Post
Would that bike have come with a 27.0 mm crown race or 26.4 mm? Unfortunately I don't have a way to measure with that accuracy, and I understand that is a tight or press fit.
As noted elsewhere, your fork could be either JIS (27.0mm) or ISO (26.4mm) spec. The only way to be sure is to measure. Can you afford US$3 for a vernier caliper?



6" Utility Caliper
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Old 01-02-16, 09:49 AM
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Braking the bike, do'nt break the bank

Originally Posted by Primitive Don View Post
I searched around and found some information, but I still have a couple of questions.

I have an '83 Schwinn Traveler, made by Giant in Taiwan. I run 700c wheels in it and have used Dia Compe centerpulls because the pads reach the rims and it brakes well.

I am modifying this into a gravel grinder bike to be able to ride off-road with wider tires, sort of a poor man's cyclocross bike. I would like to have better braking going downhill, like the V-brakes on my mountain bike, at least in front.

I have a spare V-brake, and I would like to put on a replacement 700c hybrid fork with canti bosses for the brake. When I look around, I see some with 27.0 mm crown race, some with 26.4 mm.

Would that bike have come with a 27.0 mm crown race or 26.4 mm? Unfortunately I don't have a way to measure with that accuracy, and I understand that is a tight or press fit.

I read on this forum and others that folks have used 700c forks with vintage road frames. Is there any reason that is not a good idea?
Brake pads, Koolstop , etc!, using flat bars you could upgrade cables, levers {old canti ** Make a brace that bolts on to brake pivot bolts, I have used old alloy freewheel rings , old canti braces , The pivot bolts may have to be longer. Good luck !
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Old 01-02-16, 01:27 PM
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Originally Posted by HillRider View Post
Well, if the OP's current brake is an old Dia Compe centerpull, it can indeed lock the front wheel but the hand effort needed to do so may be much higher than the OP is comfortable with so a more "powerful" brake is desired. Replacing it with a modern dual pivot sidepull (probably "long reach") is probably cheaper.
On gravel/off road, he'll be able to lock up the front wheel easily enough with either type of brake.

I agree, at set of Tektro side pulls would be a good and easy solution. A lot easier than replacing the fork and possibly headset.
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Old 01-02-16, 03:08 PM
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Thanks for the replies so far. I have borrowed a set of digital calipers to measure the headset crown race.

I used to have Kool Stops on this bike but they squealed loudly even when toed in. Dia Compe Gray Matter pads work well, but didn't make me feel very safe going downhill.

I will look into the Tektro Long Reach Sidepull. I didn't realize there were sidepulls that long or that they would be an improvement over centerpull.
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Old 01-03-16, 10:11 AM
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Ok, I got ahold of a set of Mitutoyo digital calipers accurate to .01 mm and took some measurements. The crown race fit loosely and came right off without any force, which surprised me.

Crown race ID = 26.91 mm
Steerer OD where crown race goes = 26.55

So now I'm confused. Do you think this is a 27 mm crown race on a fork meant for 26.4? Shouldn't the crown race need to be pressed on with a setting tool?
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Old 01-03-16, 10:18 AM
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.01mm is about 4/10,000"
The heat from your hand will probably expand the part several times that.

Have you taken several measurements, and see if you can repeat the same readings?
Across multiple directions to make sure the part isn't "oval"?

Just because something is "digital", doesn't guarantee accuracy.
My HF voltmeter indicates a 1.5V battery is 1.62V.

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Old 01-03-16, 10:21 AM
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ok, but should the crown race just slide right off and back on again like that? Normally I would have to use some force to remove the crown race. I thought that was supposed to be pressed on.
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Old 01-03-16, 10:23 AM
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Sure sounds like this is the case. Yes the crown race should be a press/forced fit. Sometimes when a crown race seat is cut it can come out a tad undersized but not by about .5mm! If the race were to slide onto the seat smoothly and have NO slop then a filler compound like Loctite makes could secure the race. But if there's any slop (and a difference of .4mm will be sloppy) this filler compound approach won't work. BTW calipers are a poor tool for measuring smaller than .1mm. Too much flex and slop in the jaws and people who use them generally don't have the best technique of how to minimize the caliper's inherent limits. Having said that I do use them all the time, I just don't expect much out of them. Andy.
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Old 01-03-16, 10:38 AM
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Thank you for your replies. This forum is a great resource!

I'm going to conclude, as best I can, that the fork is meant for an ISO 26.4 mm crown race, but that my bike has a JIS crown race on it. I do have a couple of forks lying around; I will check if either of those has an ISO crown race attached and if that would be better fit.

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Old 01-03-16, 11:06 AM
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Did you check the ZERO of your caliper?
My $3 caliper reads -.4mm when closed!
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Old 01-03-16, 11:11 AM
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Originally Posted by Bill Kapaun View Post
Did you check the ZERO of your caliper?
My $3 caliper reads -.4mm when closed!
It has an origin button, so you set the zero before measuring. I also checked to make sure the measurement was repeating in different places.
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Old 01-03-16, 11:33 AM
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I put a hybrid fork w/canti brake on an old road bike and I've been very happy with the results. I have way more tire clearance now, I can fit a 700x40 tire on the front with a fender and braking is 100% better than the crappy old long-reach caliper brake I had on before.

If you find a great deal on a fork don't fret over the crown race diameter. You can just get a new crown race (a few bucks) or get a whole new headset for $10-15.
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Old 01-03-16, 12:42 PM
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Originally Posted by Primitive Don View Post
Ok, I got ahold of a set of Mitutoyo digital calipers accurate to .01 mm and took some measurements. The crown race fit loosely and came right off without any force, which surprised me.

Crown race ID = 26.91 mm But is there a reason for this, aside from the aesthetic? For me weight is not a huge issue. Is there a reason why one would go with a hard, minimalist saddle and a suspension seatpost instead of a Brooks saddle with springs--or perhaps both? Personally, I prefer the aesthetic of a Brooks saddle, and currently use one on a vintage English 3-speed (a Brooks B33, wide with heavy duty springs). But for everyday cycling (say, commuting or touring) would a suspension seatpost give me an advantage over the Brooks?
Steerer OD where crown race goes = 26.55

So now I'm confused. Do you think this is a 27 mm crown race on a fork meant for 26.4? Shouldn't the crown race need to be pressed on with a setting tool?
Yup. You have a JIS crown race and an ISO race seat. You'll want to get an ISO crown race for that fork.
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Old 01-03-16, 12:43 PM
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Originally Posted by Primitive Don View Post
Ok, I got ahold of a set of Mitutoyo digital calipers accurate to .01 mm and took some measurements. The crown race fit loosely and came right off without any force, which surprised me.
Originally Posted by Bill Kapaun View Post
Did you check the ZERO of your caliper?
My $3 caliper reads -.4mm when closed!
Mitutoyo is one of the better tool makers out there, way beyond the league of $3 calipers, and about as good as Starrett in my experience.
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Old 01-03-16, 01:07 PM
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Originally Posted by JohnDThompson View Post
Yup. You have a JIS crown race and an ISO race seat. You'll want to get an ISO crown race for that fork.
The crown seat is above the tolerance limit of 26.45 for an ISO crown seat. It may be possible to force a race onto it, but there's a high risk of fracture, especially with many of the more modern headsets with crowns less beefy than the older stuff was. So if the OP wants to go with an ISO headset, he should have a shop properly hollowmill the crown seat to spec.

Going with an ISO headset introduces a new problem, if the frame is JIS. The OP can force the cups in and risk cracking the tube, or buy two headsets mixing the ISO and JIS parts as needed.

IMO the next step is to remove the head tube cups and measure those to have a confirmation of whether his bike is JIS or ISO.

If JIS, I'd build up the crown race using a center punch, and some body filler (or the punch alone if the bike won't see rough service) and stay JIS all the way. OR have both the frame and fork properly prepared to spec for ISO. (JIS frames and forks can be made ISO, but not the reverse).
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Old 01-03-16, 01:35 PM
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I've come across bikes and headsets that were a mixture of JIS head tube and ISO crown race seat or vice versa. Because of this, I've seen vendors list headsets as "full JIS" to specify that they have JIS cups and crown race. Personally, I've learned to measure both and confirm the size of both when purchasing replacements.
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