Changing from 27" to 700C, what brakes do i need?

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Changing from 27" to 700C, what brakes do i need?

Postby ldrcycles » Wed Dec 01, 2010 8:02 pm

I know there must be a thread on this already but i can't find it atm. I'm stripping and respraying a '69 Dawes Shadow to build as a fixie. It's meant for 27" wheels but i want to put flashy deep v 700C wheels on it, what reach brakes would i need to fit? The frame takes the old style non-recessed brakes so i'm guessing newer ones are out, unless there's a way of fitting them?
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by BNA » Wed Dec 01, 2010 8:11 pm

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Re: Changing from 27" to 700C, what brakes do i need?

Postby brauluver » Wed Dec 01, 2010 8:11 pm

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Re: Changing from 27" to 700C, what brakes do i need?

Postby ldrcycles » Wed Dec 01, 2010 8:17 pm

They look like the modern type of fitting, can they be made to work on an old style frame?
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Re: Changing from 27" to 700C, what brakes do i need?

Postby Mulger bill » Wed Dec 01, 2010 11:19 pm

ldrcycles wrote:They look like the modern type of fitting, can they be made to work on an old style frame?


For the rear, buy a front brake with the longer mounting bolt. A concave/flat washer and a suitable nut and you're good.
On the front you may have to dilate the mount hole on the rear of the fork slightly to accommodate the barrel nut.
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Re: Changing from 27" to 700C, what brakes do i need?

Postby brauluver » Thu Dec 02, 2010 5:44 am

Correct^
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Re: Changing from 27" to 700C, what brakes do i need?

Postby Wee Jock » Thu Dec 02, 2010 10:07 am

Tektro make a good set too, model R538 (?) from memory, I think most of the UK/US sites stock them.
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Re: Changing from 27" to 700C, what brakes do i need?

Postby yehuwdiy » Thu Dec 02, 2010 7:44 pm

Measure your frame carefully though and even try some 700C rims in your frame and then remeasure. I ahve had two frames now that were specced with 700C wheels, but were in fact made using some left over 27" parts (namely the forks). This 'transition period' is no big deal, just need to be aware that if things aren't fitting, this may be your issue.
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Re: Changing from 27" to 700C, what brakes do i need?

Postby wqlava1 » Thu Dec 02, 2010 7:58 pm

NO to most of the above posts - not because I want to disagree with these people but because the right parts are available, fit better without frame modification, and stop your bike better.

You don't want to ream out the hole at the back of your fork - it will get sloppy over time.
You want longer drop than that Diacompe brake referenced above on Velogear (although Diacompe make quite acceptable stuff when used in the right application, and i am a long term continuing customer of Velogear).
if you use dual pivot brakes, they will stop you better than single pivot - and that is one good aspect of the road caliper above.
Look for a nutted (not recessed) caliper so that it has the same bolt sticking out as your old brakes on the 27" frame.
They are available (nutted, long drop, dual pivot brakes). There is a version of the Tektro R556 (from memory) that is nutted, and which is about as expensive as you would want to go. I buy my brakes for 27" bikes from practicalcyclesUK in a no-name brand (they deal both on and off ebay), because they are reasonably priced and then also cheap on combined postage, but you might find an even better source. I have done this the right and the wrong way - I am now trying to help you be safe, to stay more original on the frame, to last longer, and to be less poor after your purchase! With decent pads the old single pivot brakes on the rear might be enough and might have enough adjustment for the extra 4mm drop from your old 27" rims - but you really notice it on the front.
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Re: Changing from 27" to 700C, what brakes do i need?

Postby ldrcycles » Thu Dec 02, 2010 9:10 pm

I am definitely not keen on drilling the forks, i've spent a fair bit of time fleabaying and so far the only nutted brakes i've found are old sidepulls, i have enough experience to know i'm better off without them. When did 27" wheels start to go in favour of 700C? This bike was only a cheap one so i wouldn't be surprised if it was 27' (and that's what was on it when i picked it up). What is the axle to crown measurement for 700C and 27'?
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Re: Changing from 27" to 700C, what brakes do i need?

Postby wqlava1 » Thu Dec 02, 2010 9:43 pm

ldrcycles wrote:I am definitely not keen on drilling the forks, i've spent a fair bit of time fleabaying and so far the only nutted brakes i've found are old sidepulls, i have enough experience to know i'm better off without them. When did 27" wheels start to go in favour of 700C? This bike was only a cheap one so i wouldn't be surprised if it was 27' (and that's what was on it when i picked it up). What is the axle to crown measurement for 700C and 27'?

Look at Sheldon Brown's website maybe first, but there is only an 8mm difference in diameter and hence 4mm difference in radius to the rim (which is really the dimension you need) between 27" and 700c. 27" is 630mm and 700C is 622mm diameter. The axle to crown will vary,but most 27" bikes were sized with enough space at the top of the forks (and under the rear brake bridge and front of the chainstays) for mudguards, so you tend to need quite long drop calipers.
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