Help wanted Viking Sprint bike.

capt_slog

Hi,

I wanted to get fitter and go out for occasional rides with my sons, so I bought a "racing bike" off the Ebay. I know it's not up to much but I'm not going to ride it lots and couldn't afford or justify anything better.

I have a small problem with it. I know that it has been repaired in the past, and this repair was to the bottom bracket. I'm pretty certain that a new one has been fitted from the look of it (clean, no corrosion etc.), however it looks to me that the WRONG part has been fitted. The reason I think this is because the inner chain wheel is far too close to the frame. The only reason it's not touching the frame now is because when the original bottom bracket failed, the wobble cut a gouge into the frame at this point; not enough to go through it, but it's taken off the paint a and a little metal. Also on the left hand side, the cup goes in further than I'd expect.

So, I'm thinking that I need a new BB with a longer spindle length? If anyone knows the part required for this bike I'd been really grateful. It's a Viking Sprint, not that new but not that old either. Mine has crossbar that is more or less parallel to the ground, the more current ones slope backwards to the seat a little more. 700c wheels, 23in frame, 14 speed.

Please note that two days ago I had never heard of a 'cartridge bottom bracket', the last time I stripped one of these was around 35 years ago and it had loose ball bearings in! I realise you will need other information to help me, but go steady OK?, it's a steep learning curve.

Thanks

keef66

You can be fairly certain it's a standard road BB, ie 68mm wide and with British threads (= drive side tightens anticlockwise, non-drive tightens clockwise). As you've already worked out, the cartridge BB's come in differing axle lengths. Easiest way to find out what you need is to get the current one out, the size should be written / labelled on it, then find one a few mm longer so you get better frame clearance.

You'll need a crank extractor to get the existing cranks off the axle, and a BB tool to get the existing BB out of the frame / put the new one back in. Shimano type is the most common, but without a photo I'm just guessing.

capt_slog

Thanks for the quick reply.

On the grounds that the non-drive side cup has 20 splines in it, I've already ordered a Shimano fit BB tool, it was in a bundle with a crank extractor for £9 so it looked like a good deal.

The 68mm, is that measured across the frame where the BB is? They are square tapers as you'd expect on this bike, but I've read that there are two standards JIS and ISO, which one is most likely?

keef66

Yes, the BB shell part of the frame should measure 68mm side to side; easy enough to measure externally without dismantling anything.

I suspect the BB in there is a Shimano type / copy, so the axle will have JIS taper. The taper on the cranks is another matter. Any identifying marks??

Luckily both tapers use the same angle, just start and finish in different places, so 99% of the time you can mix and match. Have a read on Sheldon Brown if you want the full sp / what can in theory go wrong.

In your case if your cranks are currently not constantly falling off, and you replace one Shimano type BB with another with a longer axle, you'll solve your problems!

keef66

http://www.chainreactioncycles.com/Cate ... egoryID=90

CRC have UN54 and UN 26 in a few sizes for a tenner each. The former is particularly bombproof.
I put the latter in my son's rescued Peugeot to solve a chainline issue (with an ISO taper campag chainring / crank, and an as yet unidentified NDS crank of indeterminate taper)

capt_slog

Thanks for the info.

Yesterday my tools arrived, so last night I took off the pedals and removes the BB. No doubt it's a cheapy unit, made by 'Neco', it's 68mm 1.37" x 24t and 113.5 long.

It occurred to me last night that all I really need is about 2-3mm extra on the chain side, so today I'm going to turn a spacer/washer to put in this side before I tighten it back up. Obviously this brings the left pedal in by the same amount but I reckon I can live with that.

keef66

Worth a try I suppose. Hopefully that will still leave enough thread on the drive side to hold the BB securely. Only potential problem could be if the non drive side cup has been stretched by formerly being 2-3mm further in.

Do let us know!

capt_slog

It looks ok. I made a 3mm washer and put it in the drive side. There was plenty of thread left to make it secure, and it didn't look 'wrong' on the other side. I went for a few hundred yards just to check it out and it rode ok too, a purist might notice his nuts were a bit more to one side of the saddle than they used to be, but not me.

I would have gone further, but I now have to adjust the front changer, as it was set-up for the chainwheel being in the other position.

Thanks again for you help, it gave me the confidence to go ahead and try.