Freewheel upgrade?

[Wolfie4560]

I'm currently planning out some upgrades to my tourer which has a 5 speed freewheel and 27" wheels. I'd like to fit an 8 speed freewheel and wanted to ask if it will cause any unforseen problems. Obviously I'll need a screw on freewheel and narrow chain but will the conversion cause any other problems?
It also has a double chainset which I might change to a triple and use bar end shifters.

 

[lpretro1]

An 8 speed freewheel is a rare thing - if you are upgrading you should future proof yourself by using a freehub and fitting a cassette. However you will need to be aware of the dropout width as it sounds like the bike may be quite old - modern dropout width is likely 130mm or 135mm whereas the old ones were 125mm. Depending upon the frame and its condition you may be able to spread the rear triangle - but get local good advice from someone who can look at the frame for you. New wheels are 700c size which is bigger than your 27" ones so check for frame clearance. Otherwise your option (if rims are good) would be to rebuild the wheel with a modern hub. You may well need to change the rear derailleur as well

 

[Tim Hall]

8 speed freewheels are available and changing to a freehub would mean a wheel rebuild too, so the OP's plan is fairly sensible. However, 5 speed freewheels are 120mm OLN, whilst an 8 speed is 130mm. This means the dropouts will need re spacing, by getting scientifically brutal with the rear triangle. The change sounds a lot in mm, but is less than a quarter of an inch each side.

 

[rrarider]

700c wheels have a smaller diameter than 27 inch wheels. That's why you need to fit long drop brakes. I swapped my 27 inch wheels for 700c a while ago.

 

[Tim Hall]

700c wheels have a smaller diameter than 27 inch wheels. That's why you need to fit long drop brakes. I swapped my 27 inch wheels for 700c a while ago.

I the OP is talking about removing the existing 5 speed freewheel and putting on an 8 speed. The existing 27 inch wheels stay put, so no brake faffing required.

 

[rrarider]

I the OP is talking about removing the existing 5 speed freewheel and putting on an 8 speed. The existing 27 inch wheels stay put, so no brake faffing required.

True, but lpetro1 said 700c wheels were bigger, which is wrong.

 

[Wolfie4560]

Hi guys
Thanks for the replies.

I intend to keep the original wheels at 27" and was considering just changing the freewheel for an 8 speed. The width of the hub won't be affected as its just the freewheel that will change. 8 speed freewheels are available in wide ratios and screw on. I had thought that a screw on freewheel, being an older fixing, would be the same dimensions as a 5 speed but with narrower sprockets.
I hoped that someone on here had already done this and could let me know if it is possible without causing other problems. If it can't be done, then I'll leave it at 5 speed but the extra ratios would've been nice

 

[Tim Hall]

True, but lpetro1 said 700c wheels were bigger, which is wrong.

Good point, well made. Note to self: Read the other responses properly next time.

 

[Wolfie4560]

8 speed freewheels are available and changing to a freehub would mean a wheel rebuild too, so the OP's plan is fairly sensible. However, 5 speed freewheels are 120mm OLN, whilst an 8 speed is 130mm. This means the dropouts will need re spacing, by getting scientifically brutal with the rear triangle. The change sounds a lot in mm, but is less than a quarter of an inch each side.

Thanks for the reply, Tim The frame is a 531 and given the 5mm each side, it certainly doesn't sound like a lot but could this cause problems with the cones? I would think that the 8 speed could overlap the cone nut on the drive side. It might be more prudent for me to go with 6 or 7 speed?

 

[Ed no-more-lemons]

Newish old stock seem to be rare in 6 ratios, I have always shied away from 8 speeds blocks on the bearded ones advice.

http://www.sheldonbrown.com/freewheels.html

I may well be wrong but I think the 8 speed blocks have the same distance between sprockets as 5, 6 or 7 speed blocks.

I do like 7 speed ones, but have recently fitted a 5 speed number and this can be easier to use with downtube friction shifters.

 

[raleighnut]

You need to measure the rear axle spacing,
If it is 126mm you can fit extra washers behind the cone locknut to take it to 130 in order to get a 7 on (the sprocket stack width increases as you have more sprockets) but the chain is the same 5-8 speed.

If the spacing is 120 I wouldn't try unless you can get a frame builder to replace the rear brake bridge.

 

[gbb]

What shifters do you have / intend having ?
If you have friction shifters, can wolfie use them with 8 speed ?

Or are you intending fitting 8 speed shifters Wolfie?

 

[Wolfie4560]

What shifters do you have / intend having ?
If you have friction shifters, can wolfie use them with 8 speed ?

Or are you intending fitting 8 speed shifters Wolfie?

I'm hoping to get bar end shifters, probably friction. I've seen some Dia Compe bar end friction levers on eBay and think they would suit the bike era

 

[lpretro1]

700c wheels have a smaller diameter than 27 inch wheels. That's why you need to fit long drop brakes. I swapped my 27 inch wheels for 700c a while ago.

Apologies my error. I meant to put smaller (622 as opposed to 630) - too much wine over Xmas hic!!

 

[Ajax Bay]

The difference in total width between a regular 5-speed and a SRAM 8-speed is 12 mm (24 to 36+). I'd be amazed if you could fit this in the dropouts without violence. Next the distance from smallest sprocket to the chainstay would be tight/unusable. I'd say with my 126mm dropout which had a 5-speed on (1980s) now (2009) replaced with a 6-speed the gap is max 2mm (and part of that is required for the chain sideplates, and a bit more for slight overshoot to ensure assured shifting to that sprocket). The first measurement the OP should make and share is the OLD of his/her frame. I think 5 to 8 is just too ambitious. Go to 6 first: the friction levers will do anything, so the OP can then step up to 7 if the 6sp doesn't 'do it' for them, by just getting a (relatively cheap and consumable) 7sp block: the chain (6-7-8) is the same.