JFK1

So I've gone and done it... bought several bikes new, love to cycle then picked up a really cheap steel bike from a car boot thinking how hard can it be to complete my own bike. Then reality hit once I begun the plan, to which I find myself is it possible before I start investing loads of time and money.

The bike is a Sun GT10, 70's /80's bike with Raleigh parts, the intention like I am sure of many is to strip apply some care and attention and modernise the drive train. My first issue was the 5 speed maillard cassette, didn't really have the ratio for the terrain I live in so I thought I'll change the to a larger cassette but then that has implications to wheels, seat stay distance, derailleur etc.

I have come to realise that if I wish to modernise with lighter wheels and larger cassette I need to widen the seat stays (cold setting from 120mm to 130mm, got to be very careful, I know), but also change the Huret / Raleigh RD, my concern is the hanger is part of the RD, How do I replace the hanger to accommodate a newer RD for a new cassette?

I do hope to modernise this way but am completely open to suggestions on overcoming my problem,

Thanks.

branko_76 

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Is this your bike ?

Mr. 66

Without a picture I am guessing that the Sun GT10 is a claw hanger for the rear derailleur. I'm not sure you really want to put much into from the jive I get. I myself would do modest upgrades I would keep five speed in back swap a larger freewheel, install a longer cage derailleur that can handle more chain wrap, and a triple crank to replace the double. I would keep all else stat.

If you want more modern components a different frame may be a better choice.

JFK1

Than you Mr.66. Its not that I do not wish to put much effort in, I just don't want to invest effort in the overhaul if it can't be done. I like the alternative upgrades but would still require a new cassette, RD & crank. I do wonder if I can modernise the drivetrain.

zandoval 

WHoa Boy... You are going to fit right in!

Welcomne to the Forum...

SJX426 

@JFK1 - You may want to cruise around the threads on this forum to get an idea of the challenges for what you want. What you want is not clear. By modern, what do you mean, updated friction or index? If index then DT or brake/shifter? What "speed" 8, 9, 10, 11, 12? Which brand would you like, Shimano or Campagnolo?

Since you are stuck with a claw mount for the RD, you may want to consider an RD that is one speed more than what you install to make up for the location of the claw relative to the block.

IMHO your best bet is to look for a bike with a RD mount in the DO and with the right OAL DO spread. Far less effort and expense.

daverup 

There are different levels of "modernize".
Parts are available from places like bike co-ops for reasonable prices. Ebay parts are there, but will add significant costs.
The parts available from bike shops will probably not work very well.
If you are only jumping from 70's/80s to 80's/90's there are less hurdles.
Parts are frequently sold on the C&V sales forum at reasonable prices.
Some research on this kind of thing through old forum posts will help.

Bad Lag

"Help me out before I go too deep."

My advice, which is really meant to help, is this.

Sell that bike. It is not worth investing the money to make the upgrades you are suggesting.

If you look at it as an educational experience, that's one thing, but it will be expensive.

Honest advice - buy the used bike you want not a lower tier bike that requires expensive upgrades to become what you want/need.

noobinsf 

Here's what I suggest, since this is your first old bike. Look up videos by RJ the Bike Guy on YouTube and look for information on components and standards on www.sheldonbrown.com. Make your goal for this bike to simply tear it apart, clean it up, and build it back to the original standard again. That way, you get a sense of what it's like to build a bike from scratch, you gradually learn about each of the systems (drivetrain, braking, etc) and fit. You may decide that this frame is not really worth the kind of effort it takes to modernize, and you may decide to stick with modern bikes, or you may want to look for a different bike or frame that would be worth your time. But, start slowly so you do not find yourself hamstrung by incompatible standards and diminishing stamina for a project that takes longer than you want it to. That's how I started, and I have come to love this hobby.

merziac

"go too deep"?

I don't think there is a question here.

DMC707

OP

If your bike looks like this one, you can feasibly put a larger freewheel on it , although the one on the bike in the picture looks pretty big -, but i would not exert a lot of effort into modernizing it

Looks like it could be a fun runabout though -- even putting a triple on the front would get into more than what i would want to go through for this machine as it would entail not only the crankset, but the bottom bracket and new front derailleuer also

not that i am trying to dissuade you from doing anything --- except for spreading the back end to 130mm - i wouldnt do that -- its a nice bike as a 5 speed -- trying to cold set one to 130 might very well kink the stays a little and you would have a hard time getting the dropouts aligned with such a big jump ---- generally this is done when going from 126 to 130, as this is a much smaller jump, but i have also seen well meaning folks kink a seatstay even with that jump

JFK1

Thank you.

icemilkcoffee 

Steps to modernizing the old 120mm spaced frame:
1. check to see if your derailleur hanger is compatible with newer rear derailleurs. There needs to be a notch at around 7 o'clock just below the bolt hole:

You may be able to file a notch on yours

2. Using your existing hub, you could do what Sheldon Brown suggested- run a Suntour or Regina 6 speed freewheel with 'ultra' spacing. This will allow you to run 7 speed brifters. Only issue is that these freewheels are expensive and most of them have pretty small large cogs (ie. very high geared)

3. Another option is to run the SunXCD hub:

This is a 120mm hub with a shortened freehub body, which can accomodate a 7 speed cassette with one cog taken away (ie. only 6 speeds left).

4. And then you have to deal with the nutted brake caliper. Tektro makes dual pivot nutted calipers

squirtdad

I would just ride as is and learn about mechanicing. the ROI on modernizing is not there.

perfectly good bike for what it is, but doing much to it is in the lipstick on a pig category

zandoval 

Don't forget that having a whole bunch of gear combinations is not really necessary. Especially if your not running Brifters. You can get along just fine with a Compact Crank and a Six Speed Freewheel in the back.

I do allot of short Up and Downs so I use a 34-14 in the back and a 42-30 in the front. I got along for years mounting a 34T chain ring ring giving me 52-34 up front.

I really do not use more than 5 gear combinations. I have ridden with some people that appear to spend more time shifting through thier gears then pedaling. Especially the Brifter guys. I guess its because shifting is so easy for them. No biggy. Some riders can get pretty upset with me just calling them Brifters so I don't comment. I'm just happy to have some company... Ha

Bad Lag

JFK1, here's what I would do to the bike, if I decided to go forward with the mods.

00. Remove the cable lock. Save it but do not wrap it around the frame.

0. Take the fenders off the bike.

1. Replace the rims with aluminum rims.
a) Now, that likely means finding a used set of wheels for sale that have a 120mm rear hub.
b) What I would NOT do is buy new hubs, spokes and rims to build new wheels.
c) What you might do is buy a set of inexpensive, pre-built wheels.
d) If there is any hint of age, replace the tires, too

2. Replace the seat with something a bit more rational, more conventional, less goofy.
a) A good saddle will last you a lifetime.
b) It can be transferred to the next bike you buy.
c) My Brooks Pro is almost 50 years old and is just beginning to break in. :-)
d) Get a better seat post. There are many aluminum posts modeled after the two bolt Campagnolo design. Get one of those.

3. If you need lower gearing, get an Ultra-6 Freewheel and chain. They come in a 13-34T model.
a) Your rear derailleur is a good one and can handle it.
b) If you do not need that 34T rear, stick with your 28T rear.

4. You must have a pump that works.
a) Test that one out to make sure it can actually inflate the tires to full pressure.
b) The plastic body gets brittle with time and might fracture in use.
c) Zefal makes top quality pumps that really work and are inexpensive.
d) I prefer vertical (seat tube) pump mounting as the pump is less likely to fall off when riding.

5. Ditch the turkey wing brake levers.
a) The brakes are fine but check the pads for age or just replace them with Cool Stops.

6. Check the cables for easy levering.
a) If the cable pull is stiff (friction) lube them or replace them.
b) If the brake cables are kinked or have broken strands, replace them.

7. Check the stem height to ensure there is adequate depth into the steerer tube.

8. Find some rubber hoods for the brake levers.

9. Redo the taping of the bars.

10. Replace the missing pedal cap(s).

11. Re-lube (repack) all bearings on the bike.

12. Re-install the fenders being careful to get "good lines".

JFK1

Thanks, I think given what others have suggested too. I need to have a good look elsewhere for a more appropriate frame.

JFK1

[QUOTE=Bad Lag;22622708]JFK1, here's what I would do to the bike, if I decided to go forward with the mods.

Thanks for this post, extremely helpful, I love the step by step plan, helps me immensely. I have a few comments in response though if possible...

00. Remove the cable lock. Save it but do not wrap it around the frame. Defo

0. Take the fenders off the bike. Already on it.

1. Replace the rims with aluminum rims.
a) Now, that likely means finding a used set of wheels for sale that have a 120mm rear hub.
b) What I would NOT do is buy new hubs, spokes and rims to build new wheels.
c) What you might do is buy a set of inexpensive, pre-built wheels. Is this purchase a second-hand purchase or could I buy these off the shelf?
d) If there is any hint of age, replace the tires, too Of course

2. Replace the seat with something a bit more rational, more conventional, less goofy.
a) A good saddle will last you a lifetime.
b) It can be transferred to the next bike you buy.
c) My Brooks Pro is almost 50 years old and is just beginning to break in. :-) Agreed, Brooks all the way for me and not just for touring.
d) Get a better seat post. There are many aluminum posts modeled after the two bolt Campagnolo design. Get one of those. Defo, the one on there weighs a tonne.

3. If you need lower gearing, get an Ultra-6 Freewheel and chain. They come in a 13-34T model. Again, is this an off the shelf produce? How will I know it will fit with the potential new wheels? If you have a link to both derailleur and wheels I would be most grateful.
a) Your rear derailleur is a good one and can handle it. Good to here, after some TLC it can continue its service.
b) If you do not need that 34T rear, stick with your 28T rear. I think I'm going to need it with a 42/52 up front and the overall weight and surrounding hills.

4. You must have a pump that works.
a) Test that one out to make sure it can actually inflate the tires to full pressure.
b) The plastic body gets brittle with time and might fracture in use.
c) Zefal makes top quality pumps that really work and are inexpensive.
d) I prefer vertical (seat tube) pump mounting as the pump is less likely to fall off when riding. This would be nice but I like the frame hooks on the top tube.

5. Ditch the turkey wing brake levers.
a) The brakes are fine but check the pads for age or just replace them with Cool Stops. Agreed.

6. Check the cables for easy levering.
a) If the cable pull is stiff (friction) lube them or replace them.
b) If the brake cables are kinked or have broken strands, replace them. Of course, perhaps a silly question.... is the cabling and outer sleeves the same diameters?

7. Check the stem height to ensure there is adequate depth into the steerer tube. Will do, it'll need to go down anyhow as its a large frame and I'm 5'10''

8. Find some rubber hoods for the brake levers. Defo, these look good and the comfort will be welcomed.

9. Redo the taping of the bars. YES YES YES, its currently ribbon! Comfort has come a long way.

10. Replace the missing pedal cap(s).

11. Re-lube (repack) all bearings on the bike. Defo.

12. Re-install the fenders being careful to get "good lines".

Murray Missile 

[QUOTE=JFK1;22622836]Why? I wouldn't add them to a bike but when I get a bike like that with them I make the best of it. With good cables, pads and aluminum rims they can work great and can even work pretty nicely on steel rims. I have a'74 Varsity Deluxe that came with them, it's 45 Lb. behemoth with chrome steel rims and the original side pull brakes. Before I lost weight I was 230+, (212 this morning) so we're talking around 275 Lbs. of mass total rolling down the road. 97% of the time I ride it with my hands on the curve at the ends of the bar and I can grab the curved part of the turkey levers and bring "Big Bird" to a panic stop VERY quickly. I think grabbing them on the curve improves their effectiveness because you're putting a straighter pull on them and not losing leverage from them flexing by pulling on the straight section. Or not. Give them a try before you ditch them, you might find them useful, kind of poor man's interupter levers.

Big Bird:

Bad Lag

[QUOTE=Murray Missile;22622886]Just my personal preference. Leaving them is probably easier, too.