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27" conversion to 700c

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Old 12-26-07 | 12:48 PM
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27" conversion to 700c

I posted this in mechanics also.

A Schwinn I have originally came with 27" wheels and I only have 700c to put on it. I bought 2 'dropdown' bolts for the campy side pull brakes I have and find that the brakes are still not low enough. I seem to need another 1/8-3/16" reach??? I thought that drop down bolts were the fix for this problem??? That is why they made them in the first place.

You have any knowledge on this issue?

Oh, if you are going to tell me to measure my Campy brakes, I will need to know from where to where.
What knid are they? Campy side pulls from the 60s I guess.
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Old 12-26-07 | 02:12 PM
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I converted a Letour that was originally equipped with 27" wheels and long reach brakes to 700c. I believe the OE brake reach reach was 55-57mm fully extended and they were just short.

I ended up using the Tektro R556 which have an adjustment range of 55-73mm (measured from the mounting hole to the brake pad mounting bolt in the adjustment slot). They are very nicely finished dual pivots with a quick release. Got em on E-Bay new for $55. No regrets, I would recomend them.

To determine the reach required measure from the mounting hole to the center of the braking surface on the rim.
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Old 12-26-07 | 03:14 PM
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I'm not surprised. The problem is not that your are trying to use 700c in place of 27" wheels... thats only a difference of 4 mm (1/6th of an inch). The issue is trying to mount a short reach brake - which even back then was designed for dedicated racing bikes which would have had very tight clearances for narrow, low profile tires. Even my own top-end Schwinn, a 1971 Paramount (the "Sport Touring" model, rather than the Racing model), was designed for 27" clincher tires and wider (therefore taller) 27" tires, and with even enough room above them for fenders.

I could not use most Campy brakes on my frameset, even with standard drop bolts and 27" wheels. The previous owner had tried to set it up this way, so I got the bike with excessively expensive Campy brakes along with some very expensive Campy drop bolts... which were basically just worthless for the bike even with 27" wheels.

Campy actually made two different brake caliper models, one had slightly longer arms allowing a reach of up to 52 mm, but most I've actually seen were the shorter arm style with a reach of only 47 mm - like most modern brakes. The Campy drop-bolts I have only give an additional 8 mm or so. Most any better quality Schwinn road bike in the 60s/70s would have used the premium quality Weinmann center-pull brakes which had a reach of up to either 61 or 75 mm depending on the particular caliper model... a considerable difference from that and the Campy calipers. The drop bolts do not offer enough additional length to bridge too great a gap.

Again, I'll use my bike as an example: _ Using the longer (rarer) version Campy brakes, and adding a drop bolt, the front caliper would still be shorter than the 61 mm caliper reach needed for my current 27" wheels. The Campy caliper + drop bolt will simply not fit- even on the front... and, the rear brake requires considerably more reach than the front!

Not an expert on the subject, but I think the drop bolts were indeed intended to help switching wheel sizes... but on frames already designed with tighter wheel clearances. But, not to help change the frame design to accommodate it for use of the short brake calipers.
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Old 12-26-07 | 04:19 PM
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Originally Posted by stronglight
I'm not surprised. The problem is not that your are trying to use 700c in place of 27" wheels... thats only a difference of 4 mm (1/6th of an inch). The issue is trying to mount a short reach brake - which even back then was designed for dedicated racing bikes which would have had very tight clearances for narrow, low profile tires. Even my own top-end Schwinn, a 1971 Paramount (the "Sport Touring" model, rather than the Racing model), was designed for 27" clincher tires and wider (therefore taller) 27" tires, and with even enough room above them for fenders.

I could not use most Campy brakes on my frameset, even with standard drop bolts and 27" wheels. The previous owner had tried to set it up this way, so I got the bike with excessively expensive Campy brakes along with some very expensive Campy drop bolts... which were basically just worthless for the bike even with 27" wheels.

Campy actually made two different brake caliper models, one had slightly longer arms allowing a reach of up to 52 mm, but most I've actually seen were the shorter arm style with a reach of only 47 mm - like most modern brakes. The Campy drop-bolts I have only give an additional 8 mm or so. Most any better quality Schwinn road bike in the 60s/70s would have used the premium quality Weinmann center-pull brakes which had a reach of up to either 61 or 75 mm depending on the particular caliper model... a considerable difference from that and the Campy calipers. The drop bolts do not offer enough additional length to bridge too great a gap.

Again, I'll use my bike as an example: _ Using the longer (rarer) version Campy brakes, and adding a drop bolt, the front caliper would still be shorter than the 61 mm caliper reach needed for my current 27" wheels. The Campy caliper + drop bolt will simply not fit- even on the front... and, the rear brake requires considerably more reach than the front!

Not an expert on the subject, but I think the drop bolts were indeed intended to help switching wheel sizes... but on frames already designed with tighter wheel clearances. But, not to help change the frame design to accommodate it for use of the short brake calipers.
Sounds like you have it nailed being involved before.
So, as i read it you have tried the drop bolt and still ended up short as I am now.
"The drop bolts do not offer enough additional length to bridge too great a gap."

I have the Weinmann center-pulls, which came on the bike, but sure like the Campy look better. I may just have to go back to Weinmann and my Campy levers.

Thanks
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Old 12-26-07 | 05:12 PM
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On a long clearance frame, good old Weinmann or MAFAC centerpulls are still your best bet.
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Old 12-26-07 | 06:33 PM
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FWIW, I agree with the other recommendations to forget the Campy side-pulls and put the Weinmann center-pulls back on.

My '72 P15-9 was originally equipped with 27" wheels and Weinmann center-pulls (610 front, 750 rear), and when I switched to 700C the Weinmanns' reach were just fine. There's no way standard reach Campy side-pulls would have worked.

BTW, what's the model name/year of a Schwinn C19?
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Old 12-27-07 | 11:49 AM
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Well, if I am to look for a NICE looking set of center pulls then, what are the reccommendations? My Weinmann's do not impress me. Could be because they are dirty and old. perhaps they will shine up. But if i am to replace them, who has great stuff to go with my NEW old vintage Campy drilled levers?
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Old 12-27-07 | 12:26 PM
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Originally Posted by jjciiijs
Well, if I am to look for a NICE looking set of center pulls then, what are the reccommendations? My Weinmann's do not impress me. Could be because they are dirty and old. perhaps they will shine up. But if i am to replace them, who has great stuff to go with my NEW old vintage Campy drilled levers?
The Weinmann's will shine up nicely, and with the "salmon" Kool-Stop Continental pads they are very effective. Beauty is in the eye of the beholder, but I think they look nice. These are the Weinmann's on my '72 chrome P15-9 Paramount originally equipped with 27" wheels but now sporting 700c wheels. The reach is perfect. Everything else on the bike is Campy Record or Campy Nuovo Record, and the OEM Weinmanns look right at home.

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Old 12-27-07 | 01:44 PM
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Originally Posted by Scooper
FWIW, I agree with the other recommendations to forget the Campy side-pulls and put the Weinmann center-pulls back on.

My '72 P15-9 was originally equipped with 27" wheels and Weinmann center-pulls (610 front, 750 rear), and when I switched to 700C the Weinmanns' reach were just fine. There's no way standard reach Campy side-pulls would have worked.

BTW, what's the model name/year of a Schwinn C19?

Same with my 73, the Opaque Blue one. I did substitute Campy brakes on my chrome P-13, but the clearance is much less than on a P-15.
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Old 12-27-07 | 01:50 PM
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I really like the Weinmann Carrera sidepull brakes as a long-reach alternative on vintage bikes. The one's I have measure about 65mm reach, I believe. Some info here:

https://www.classicrendezvous.com/Swi...m_carr_pix.htm

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Old 01-08-08 | 12:28 PM
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Well I measured the range needed for both brakes with the 700c wheels.
The front is 60-70 and the rear is 65-75.
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Old 01-08-08 | 12:57 PM
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Originally Posted by jjciiijs
Sounds like ... I may just have to go back to Weinmann and my Campy levers.
No mention of relacing with 27" rims?!?

Of ALL my bikes, only the Tour Easy HAS a 700c wheel!

The Colnago, 3 Gitanes, the Clive, The Raleigh, & the Merlin are all 27"ers.

OK, the Rock Lobster is the one bike that has sew-ups in 700c size.
(the TE has a clincher rim)
 
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Old 01-08-08 | 02:21 PM
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Just a slight sidetrack here...

Are 27" rims available that have the hook bead to handle modern high pressure tires?
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Old 01-08-08 | 02:32 PM
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Originally Posted by barndoor
Just a slight sidetrack here...

Are 27" rims available that have the hook bead to handle modern high pressure tires?
Yes they are. There is a seller on ebay that lists 27" rims. I was interested at one time and asked the seller if they had hook beads, he said yes.

I have a set of Weinmann rims on one of my bikes that is 27" and has hooked beads.

https://cgi.ebay.com/WEINMANN-POPULAR...QQcmdZViewItem

I'd still try to verify that with the seller. They look like hook bead in the photos.
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Old 01-08-08 | 02:34 PM
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Originally Posted by barndoor
Just a slight sidetrack here...

Are 27" rims available that have the hook bead to handle modern high pressure tires?
You bet! Sun CR-18 or Sun M-13II are 27" rims with hooks.
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Old 01-08-08 | 03:11 PM
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I got Campagnolo sidepulls to fit my 73 touring Paramount with 27" wheels with a dropbolt in the rear and a little filing to the slots on the front. Not crazy about those Weinmann rims though...
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Old 01-08-08 | 03:56 PM
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Originally Posted by barndoor
Just a slight sidetrack here...

Are 27" rims available that have the hook bead to handle modern high pressure tires?
And these very affordable 27" Alex rims are available from Nashbar at $15 each. They're not all that fancy but they get the job done. I have a pair on my '62 Continental and I'm quite pleased.
https://www.nashbar.com/profile.cfm?c...okes%2FNipples
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Old 01-08-08 | 03:58 PM
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Originally Posted by Scooper
You bet! Sun CR-18 or Sun M-13II are 27" rims with hooks.
Plus you can get those in a polished finish which looks fantastic.
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Old 01-08-08 | 04:08 PM
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Originally Posted by Lamplight
Plus you can get those in a polished finish which looks fantastic.
Sun CR-18s do look great. I have a pair laced into high flange hubs. Very vintage looking.
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Old 01-08-08 | 05:12 PM
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Originally Posted by dbakl
Not crazy about those Weinmann rims though...
I can see why. They do make the tires look flat.
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Old 01-08-08 | 05:20 PM
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Excellent!

Thanks for the responses, all!
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Old 01-08-08 | 06:03 PM
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Originally Posted by pastorbobnlnh
Sun CR-18s do look great. I have a pair laced into high flange hubs. Very vintage looking.
I've got a pair of each (in 700c) on two bikes and they both seem to be great rims, although from the cross section diagrams I would think the CR18 would be stronger.
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Old 01-08-08 | 06:28 PM
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Originally Posted by Lamplight
I've got a pair of each (in 700c) on two bikes and they both seem to be great rims, although from the cross section diagrams I would think the CR18 would be stronger.
I agree; I think the two longitudinal ribs in the nipple well add strength and rigidity.
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