bres dad

I'm going to look at an older Trek 400 to build up for my wife for Christmas. It has 27" wheels. The plan is to put 700c wheels on it to modernize it and use integrated shifters/brifters (my wifes hates downtube shifters and refuses to ride anything with it). I know there is a slight difference in size between 700 & 27" but which is the larger? If 700c is smaller I'm assuming this will work though I may have to put some longer reach calipers on it, at least I'm hoping I can do it like that.

bicyclelove

700c is smaller. This conversion usually works fine with the brakes you have. The pad position just has to have enough vertical adjustment. It's only like 4mm.

andr0id

Well, that really depends on whether the existing brakes are SLR or not. If you mix/match SLR and non-SLR, braking will feel wrong. If you go to new SLR brakes, they may not have enough reach because most newer brakes have short arms.

You need to do a lot of measuring before you decide to spend a lot of money on this.

hueyhoolihan

IME, it's been a piece of cake. i have two old treks made for 27" wheels (630mm rims). i never had any trouble finding calipers (single or dual pivot) that would fit or levers (including BMX levers) that were satisfactory.

bicyclelove

andrOid is right on. I glazed over the change to brifters sorry about that.

bres dad

The hardware on the bike is original as far as I can tell. I haven't seen the bike yet, its two hours away and I'm supposed to see it this weekend. I'm researching, trying to figure out if this will even work. Here is a catalog link with all the specs & component list:

https://www.vintage-trek.com/images/trek/85TrekSport.pdf

Brakes are Diacomp Q500N. In the photos I've got, it looks like the rear pads are as far down on the calipers as possible. If I do go, I'm planning on taking some 700c rims with me.

Does anyone know when Trek switched over to 700c on their steel frame bikes? My goal is to find a nice vintage steel frame trek for her. Ones I've found in my area so far either are the wrong size, junk or seller is asking more than I'm willing to pay. This specific one is the correct size, is in good shape and is within what I'm looking to spend.

bikemig 

Buy it then. This is not a difficult conversion.

Little Darwin

+1

The most you will need to convert to 700c is to replace the brake calipers... I haven't done it, but even if the brakes are nearly as low as they can get, I believe I have read from the late Sheldon Brown (and others) that it is fine to use a file and extend the slots. As long as there is enough surface for the pads to grip properly, you should be good to go.

Al1943

My 1980 Trek 510 was originally equipped with 700c wheels.
Converting the shifters and drive train to STI can be challenging and expensive. I don't see any real cost savings in converting a pre-STI bike to an STI bike. Of course it can be done with good results but it may cost more than a new bike and will probably be heavier.

bikemig 

The OP can leave the original wheels on the bike and go with a 7 speed shimano f'wheel and 7 speed brifter,

Amazon.com : Shimano ST-A070 Road Shifters 2 x 7-Speed Black Pair : Bike Shifters And Parts : Sports & Outdoors

https://www.amazon.com/Shimano-MF-HG3.../dp/B001IORDH0

rpenmanparker 

I wouldn't change to 700c wheels. I have done it before, and it just doesn't work out so well. First of all it looks funky. If you can find a decent set of tires for her, then there is no reason the change to 700c. Though honestly I wouldn't buy a 27" wheel bike anymore. That is just over. So I'm saying don't get into this, but if you do, just keep the 27" wheels. Otherwise you will be throwing good money after bad. There are plenty of comparable steel bikes from the 700c wheel era that you don't have to settle for a problem.

Jax Rhapsody

Pftt, do it if you want, much bettr choices in tire, and most people wouldn't even be able to tell. He said he's upgrading the bike- no different than restomodding a classic car, if the pads don't sit in the brake surface properly, buy some new dual pivot calipers, they make it easier to change flats, anyway. The only thing about brifters is the bike won't look as clean, with the shifter cables hanging out there mtb style.

delcrossv

27 x 1-1/8 Panaracers and bar end shifters

fietsbob

Radius is 4mm less on 700c. ( recommend: Friction Bar end shifters , for unknown drive train , you have not mentioned )

Brifter convesion on an older bike is going to burn thru such a sizable pile of cash .. better to Go Shopping for a New Bike equipped as Now desired

bres dad

It has 6 speed Shimano 500 something on it. I have a 7 speed drive train & 700c wheels left over from another build I'm planning on using along with some 7 speed ST-70 shifters a friend has and isn't using, so the immediate plan is to use those and I'm not out anything except possibly brakes. If she likes it and uses it, I've got a Shimano Ultegra group she might be able into talking me into giving her. If she ends up not liking it, it will probably go back out on CL. We'll see.

I have an older broken frame I was going to use for some wall art I pulled out and low and behold, its a Trek 400 (though I think a bit newer than the one I'm looking at getting.) 700c will work fine.

I've upgraded a few older bikes from down tube to brifters, so that is nothing new. I just haven't dealt with 27" wheels on one in along time. I have an old Paramount my wife loves but I won't let her ride it (she nearly destroyed it twice taking it out.) She loves Trek and kinda likes the vintage gear, so a vintage Trek just makes sense. She has a '14 Giant Avail so she has a newer bike... time for an older one.

Paramount1973 

27" to 700c is an easy conversion if you have the 4mm brake reach and is all but invisible to the eye. 4mm is only 5/32 of an inch, just a hair over 1/8".

GravelMN

Gevenalle - Cyclocross

Here ya go. These used to be branded as Retroshift. Road brake levers that accept your current DT shifters and put them up in easy reach. Bombproof, work like a charm, and all it takes is installing a cable housing stop where the old DT mounts are (bolt on conversion from several companies). They also make it easy to convert to 9sp if you want, but then the $$$ for the project goes up.

As far as switching from 27" to 700c, no problem 95% of the time. Worst case scenario is that you have to find some good, long reach dual pivot brakes, but often the stock brakes will have enough adjustment. Find some plain silver rims with 32 silver spokes laced 3 cross and they will look very much like the original wheels.

Added bonus: The 4mm decrease in radius also means slightly more room for tires. Sometimes (not always) you can go up a width from what you could with 27" wheels.

Easy project, low to moderate cost. Sure the older steel frames might weigh a bit more, but if you get butted cro-mo, they are a decent weight and ride like a dream. Since you are looking at vintage, I'm guessing your wife isn't a weight weenie or planning to race, so the comfort of vintage steel might be just what she wants.

All that said: don't discount the original 27" wheels. If they are in good condition with decent tires, ride them for a while. As mentioned, the difference in diameter compared to 700c is minor and you can get some good use out of them unless you are looking for something specific that you can't get in 27".

bres dad

Another possible area for concern. Since I'm going to be switching to brifters, cable stops will be needed. This bike is older than others I've converted using brifters and uses a bracket instead of braize on shifter mounts. I found this on vintage-trek.com. Could this be a game changer?

https://www.vintage-trek.com/refurbish.htm
A caution - some downtube clamp-on shifter bosses made for friction shifting, that may be on your lower to mid-level Trek bike, are not compatible with standard shifters that fit on brazed-on bosses. Downtube cable stops also will not fit on these nonstandard types of clamp-on bosses.

cyccommute 

First, the wheel conversion isn't that big of a deal. If the bike has the original brakes, the Treks of that era were made to use either wheel size for the US (630mm rim) and European (622mm rim) markets. The pads will slide down in the brakes and should be simple matter. You could even use a modern wheel, i.e. 130mm OLD hub, in the bike without having to do any modifications. You'll just have to spring the rear triangle out by hand to get the extra 4mm into the dropouts. It makes wheel changes a tiny bit more difficult but not impossible.

The clamp on shifter mounts shouldn't be any barrier to converting over to an STI system. You just replace the downtube shift levers with a downtube cable stop like this one. It appears that you are using a quote from somewhere...you are supposed to say where you got it from...but I've never had a problem with putting on a cable stop like the one from Ben's Cycle on a clamp on stop. The shafts are a standard size. At the very least, try the cable stop before you go worrying about whether it will work or not.

bres dad

Since I've started the post I've realized the wheels aren't a factor. The shifter bracket is a little concern. I assumed there wouldn't be a problem but thought I would ask people who know more about older bike compatibility issues then me.

As far as where I got the quote, I did put that in there, vintage-trek.com. I will admit I see it didn't copy https://www but I've edited my post. I wish I had found this site (vintage Trek) before. It answered many questions I've had on this bike.

spoiledrotten

Question from a newby. If there's so little difference between the 700 and the 27" (around an 1/8"), why even go to the trouble? Will it really make a difference in the bike?

LesterOfPuppets

The best reasons for going from 27" to 700c are that the new tire and rim choices are 1:10000.

fietsbob

Planning a Rear dropout Cold setting, pry apart. ?

Stuffing a 130 axle* in a 126 rear dropout when 2 people have to Pry the stays apart ,to get the wheel in eliminates the ease of on the road Puncture mending .


* Most-all current road bikes and their Indexed shifting schemes with Brifters ..

bres dad

Correct. I have two other 80's bikes I run 130mm wide wheels on. The wheel set I have I plan on using for this one is 126mm.

The original question of this post, 700 vs. 27" is solved (I only posted that as I was getting conflicting information from my local stores so thought I'd go here.) I stopped at the LBS again and talked with them on my concern of the shifter bracket & while they agree its a valid concern, they have the parts to make it work if the shifter bracket is an odd ball. I think I have what I need to move forward.

Leebo

Tektro makes some long reach brakes that I have used before. The 27>700c conversion also allows you to run bigger tires if needed.