Advice Wanted - Change(s) for Lower Gearing

[Double J]

Hi,

I have a late 80’s Peugeot Aravis with original Shimano 105 groupset, which includes a 52/42T Biopace chainset and a 6 speed 13-21 tooth cassette with short cage rear mech controlled by shift index levers on the downtube.

Front mech also controlled by lever on downtube, but not shift index (just gradual movement).

To assist on climbs, I am looking at what alterations can be done relatively cheaply to obtain some lower gears.

My initial thoughts are:-

1. Change Biopace to compact or triple (will front mech need to be changed? Will compact/triple fit onto existing bottom bracket or will it also need changing? Special tools required?)

2. Change cassette with larger  unit (what max. size likely to be suitable? Compatibility with modern day cassettes? special tools required?)

Hoping to do the changes as a DIY project, if anyone can offer advice it would be much appreciated.

Cheers

JJ 

[Paul Rainbow]

Hi JJ,

Sounds like an interesting project. Should all be quite acheivable. The rear 6 speed free hub body is your main issue really but quite simple to sort out. You will find it hard to find a 6 speed cassette these days in any size let alone a wider range. Best thing to do is replace the 6 speed free hub body with a newer 7 or 8 speed version. After removing the 6 speed cassette (will need a chain whip) Remove the axle, and the free hub body can be unscrewed with a large Allen key 10mm I am pretty sure.

Then replace with a 7 or 8 speed version (7 may be easiest and cheapest option) when fitted you will have a wider range of ratios available but something like 12-28, 12-32 will be a good starting point.

The short cage rear mech will need replacing with a long cage to handle the wider range of gears. The 6 speed shifter should be ok to use as they normally have an extra position allowing them to run 7 speeds.

That should give you good starting point for a wider range of gears, then if you decide you want more the front chain set can be looked at. If you measure you bb axle length you can see what options are available. The front mech may handle a triple but a compact double should be fine.

Good luck whatever you decide to do!

Cheers Paul

[fruitcake]

http://www.cyclespeugeot.com/images/scan0009.jpg shows that the bike has a freewheel on threaded hub.  

I think 6 speed indexed down tube shifters is a very useful set up - simple, usable and reliable.  

However, 13-21 is what people raced on.  Everyday utility riding was done on 14-28 - or 14-24 if you wanted closer spaced gears.  I'm going to tell you how to change the freewheel. 

Obtain the correct type of freewheel remover - if it is a shimano freewheel, you need the shimano kind of tool - I recommend Park Tools as a brand, you will also need a one inch spanner, although a large adjustable spanner will work.
Using the freewheel tool and the spanner, unscrew the 13-21 freewheel.  If it won't budge, squirt some penetrating oil at the threads and leave it overnight then try again.  It will come off eventually.

Replace it with a 14-24 freewheel.  It should work with the derailleur you have.  This will give you a bottom gear 14% lower than you currently have.  

You will probably need to add chain links, and you may need to replace the chain if it is worn.  This will involve obtaining a chaintool and a new chain.  Six speed chain is inexpensive and highly durable.

If you need lower gears still, you can opt for a 14-28 freewheel for a 25% reduction, but that probably won't be necessary.

(A 39/52 chainring or a triple chainset will make a slight difference but the triple may require a different front derailleur to allow you to access the small ring, may also need a different bottom bracket which will require a special tool for the removal of cranks and one for the removal of the BB. So, don't worry about that until you've sorted the freewheel - which will probably give you all the gearing you want.)

(Cyclofabrica, the main problem with changing to 7 or 8 speed is axle width incompatibility, besides the need to replace shifters - DT friction is a chore.)  

[Double J]

Gents,

Many thanks for taking the time to share your knowledge.

I will now shop around to see if I can find a larger 6 speed freewheel and replace, as this appears the easiet solution and see how I get on from there.

It was great to use the link to browse through the peugeot cycles web pages, as I recall having a 1988 catalogue prior to buying the bike from mail order company based in North Wales where I bought the bike from new, since then it is still as original, except bar tape, bottle cage, peddles and a few spokes replaced along with a few rust spots.

However, 23 years on being less fit and about 5 stone heavier the gears need to be reviewed to make things easier, so some of the originality needs to go.

Thanks again for your replies.

Best Regards

JJ

   

[Karla]

Remove the axle, and the free hub body can be unscrewed with a large Allen key 10mm I am pretty sure.

Yes, if it's a Shimano freehub it will be removed with a 10mm allen key.

[EDIT: The Specialized hub that used to be on my Allez required an 11mm allen key for the freehub.  I have a Quando hub that requires a 12mm allen key, though it's screwed on tighter than a [insert lewdness here] so I can't get it off anyway.  ]

Then replace with a 7 or 8 speed version (7 may be easiest and cheapest option) when fitted you will have a wider range of ratios available but something like 12-28, 12-32 will be a good starting point.

6 speed and 7 speed gear systems used rear spacing of 126mm.  8 speed used 130mm.  It will therefore be easiest to run 7 speed rather than 8 speed, as the latter will require the frame to be re-spaced and  new freehub body fitted, whereas 7 speed should let you keep your freehub and leave your frame alone.  There's a Sheldon Brown article about this here and I believe Charlotte on this forum has a good blog about re-spacing a frame, if she'd care to provide a link.  Re-spacing is eminently doable on a steel frame, but not if you're looking for the easiest solution.  Then again, 8 speed gears are more readily available than 7 speed these days, so biting the bullet and re-spacing has its advantages.

The short cage rear mech will need replacing with a long cage to handle the wider range of gears. The 6 speed shifter should be ok to use as they normally have an extra position allowing them to run 7 speeds.

Depending on how much lower you want your gears, you may be able to keep the mech.  My short cage rear mech very nearly copes with 52-39 12-28 gearing, so it should cope fine with 52-42 12-28 and anything narrower than that.

[Double J]

All, thanks for taking the time out to give the great advice. 
After much searching around on the web for the required parts and tools, I must confess getting side tracked and drawn towards a BNWT Cannondale with triple in the sale, which came in useful for the Cotswold Corker on the weekend. So Cyclofabrica, you can expect to see me on a red bike with a cadence > 45, unless on a flat ride where the Pug may make a guest appearance, then cadence less than 45.

[Torslanda]

Peugeot Aravis 

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