Bottom Bracket Sizing

Guys. I have just purchased a new frame but don't have much info on it except to say that it's brand new (well never used and new enough for disc mounts), 17", unpainted, magnesium alloy, 3lb and is one of the Saracen Kili's.

Anyway... on the build up I'll need to fit a bottom bracket but not having one fitted I'll need to size it. I have a couple old spares in my tool box I could use as a guide but there must be a way of properly measuring this?


Cheers.

Craig, do you mean the axle width or the diameter or both?

Both although I hadn't thought about the diameter.

Taking a look at CRC there's 68/70/73 for the diameter and 113/118/121 lengths. I guess the diameter is a straight mm measurement. Does the axle length actually mean from one end to the other? I'll measure my old ones tonight.

Clearly I'd need to ensure the front chainrings sit out enough to clear the chain stay but not too far I can't select granny at the rear.

Cheers.

You can prob measure the diameter of the BB shell on the frame. Will more than likely be 68 or 73.

As for the axle length, these are crank specific and it shouldn't therefore matter what frame you use. So if your transferring your existing cranks to the Kili, providing the diameter is the same the cranks/BB will be fine.

Ah....

I am running an XT crank, can't remember taking any size measurements from the old one when I upgraded but I guess I must have done. I know I altered the ratio.

So taking a random crank size from CRC what does the 170mm measurement refer to? I am clear on the rest.

170mm 4-Bolt 22.32.44

I think the 170mm refers to the length of the arms

yep length of the arms.

175 is the norm.

It should say the length on the back of your existing ones.

As soon as you said crank arm length the penny dropped.

Cheers guys.

Have you built this up yet Craig?

Dude, no not yet.

The story so far... I got the frame back from the painters last Saturday. It's been stove enamelled and lacquered. I went for a light gun metal in the end. At this point I have to say a BIG thanks to Becci Allen at Saracen Cycles (will email her a link). The seller of the 'never been used or painted frame' said that he thought it was a Saracen Kili Flyer. My research only took me so far so until I contacted Saracen. Becci got an engineer to look at some pics of the frame and diagnosed it as a 2003 Kili Flyer 1. After this point it appears they stopped using magnesium and switched to alluminium. The Kili 2 and 3's use carbon. Becci even sent me some free P clips for the hydraulics as it has bosses running along the top tube and chainstay. I am very impressed with Saracen, considering that they don't deal direct with the public and work through resellers.

I need to get a 27.2mm x 400mm seat tube. The rest of the gear on my current bike will transfer across (for the time being but don't tell the Mrs). I want to use stainless braided hoses (replace my black stuff) and will need to replace my other cables. I curently use Avid Flakjackets as they've been the only trouble free cable I have used. Would quite like straight carbon bars and a carbon seatpost but may have to wait.

Anyway my wallet is now closed until next payday. I am doing the SPAM Winter Challenge on 7th Jan so will run my current bike until after payday and hopefully build up then.

Sorry if I waffled on... I'll rent the community centre when it's built and run a slide show....

Oh... the painter, well he outsources that bit, his main trade is building bikes... http://www.leecoopercycles.com

Sounds like your putting alot of time and effort in, good to see, I'm sure it'll be very rewarding when you take it out for it's maiden voyage.

Don't forget to post pics

Craig, sounds like an epic build. Any pics of the beauty yet?

I had a look on Lee's website. And £100 for a full shot blact and spray sounds pretty darn good.

I've always wanted a personalised paint job, I might have a think of a design !

Dude,

I went for light gun metal but it wasn't my first choice. As it happens I now think it's a better colour than what I was going to go for. I had the frame enamelled and over lacquered.

If you absolutely want THE colour then learn from my mistake.

1. Speak to Lee about the paint options and ask what type of paint he'll use as a colour layer.

2. Get your exact colour mixed up in the relevant type of paint at an auto paint suppliers.

3. Sketch out or provide your own graphics for over lacquering.

I didn't want graphics but I wish I'd have pitched up with my own tin of paint - I am still happy though

Link to the build so far. That'll just be the painting then ....

http://bwffw.servehttp.com/bike/SaracenMagnesiumKiliFlyerImages.pdf

Oh if you're thinking of a colour then allow hmmmm about 12 months!!! It's worth having an aircraft hangar full of bikes just to satisfy 'colour lust'... so many great colours. Lee had a really funky metallic orange that looked great but you'd need to be doing 20 + mph everywhere and pulling somersaults where everyone else gets 4 inches of air just to pull it off.

Craig, have you got you painted frame back yet?

Whats the finish like? Will it survive minor shoes scuffs etc?

How long did it take to turn around?

I think Lee turned it around quite quickly as it was just before Christmas and no doubt a bit of extra cash is always welcomed. I think the turnaround was 1 week, Saturday to Saturday but it could have been 2. It was stoved but I asked for some over lacquering as well. Looks rock solid. It has a couple of tiny blemishes but nothing anywhere obvious. The overall finish is very good. I have got an order list about to go to CRC for the bit n peices I need so I'll update this thread when I know more about the toughness of the paint. Stove enamel is well known for being good stuff so I expect it to be fine.

Hi Craig

Interested to read about your new frame. I've got the 19" version and have just completed a light weight build with mostly s/h bits off Ebay and STW.

I had the same issues about the b/b and the granny ring is about 1.5mm off the chainstay.... Seems to work OK though - have taken it out for a couple of spins and will try it for real on Sunday at the next Soggy Bottom race in Plymouth. I did try to space the b/b out but although the chainline seemed OK I couldn't get the front mech to stop scraping the chain in the middle and big ring highest gears. Generally the transmission doesn't seem to be as well sorted as it might be so I would be interested to hear how yours pans out.

The colour I went for is 'anthracite' powdercoat which looks smart but understated....

Spec' is RC38 Airforce 2 fork, Crossride wheels, Mini Monos, RF Turbine chainset with Middleburn rings, Kooka Race stem, Pazzaz carbon straight bar, no name carbon seat post, San Marco Aspide saddle, XTR shifters and rear mech and Deore front mech. Was supposed to be economy build but still ended up about £800 inc frame.

Took me a while to sort out the hose fixing - but I ended up with nylon p clips. The thread size is M3.5 - and I'm using the same screws used to fasten wall sockets on.... To keep things tidy I also fitted rivnuts for a Crud Catcher - so no rubber bands or cable ties to scratch the paint. Was a bit nerve wracking drilling holes in the down tube though.

Look forward to seeing your pics.

Cheers

Marcus

How tall are you? I am 5'10 or 11 ish and went for the 17" version. The seatpost to head length is the same as my current bike but the BB to the seatpost clamp is shorter so I need a 400mm seat tube.

Saracen sent me some free P clips and screws. Are you using the screws that hold a socket/light switch to the plastic/galvanised patress/backfitting?

Interesting to note you used rivnuts. I had noticed the lack of bosses, just the water bottle one on my frame. I'll have to look into them - got any good links?

I am hoping it's going to be a good ride after all this effort ! The build so far is

http://bwffw.servehttp.com/bike/SaracenMagnesiumKiliFlyerImages.pdf

6' and with longish legs. I was going to have the 17" frame but talking to Peter Darke went for the 19" which was the right move I think.

Yeah, those are the screws - I wanted to get s/s socket pan head ones - but you can't get such things very easily so I'll see how the DIY stylee ones go.

I got the rivnuts from here: http://stores.ebay.co.uk/WVS-FASTENERS
and s/s screws to fit from here: http://stores.ebay.co.uk/Aruncas

If you wanted to use M4 rivnuts I've got a load more than I need, so can post you some, no worries. On balance if I was doing it again I'd go for M5 though - slightly more robust although with M4 I could get away with a 6mm hole in the tube. I used aluminium because they weigh vitually nothing and you can avoid the need for a special tool for the squishing bit, although it does mean a small amount of bodging. Steel rivnuts are a pig to fit unless you have the right tool.

Re the ride - I haven't had an aluminium hard tail so can only compare it with a full suss and steel rigid. Basically it's very light so acceleration and going uphill are great, within the significant limits of my fitness. Feels compliant on the bumps which is combination of the carbon post and magnesium I think. I'm very pleased with it. I'd post some pics but I haven't quite sussed these hosting sites yet.

I found an old magazine review of the basic Kili build here: http://www.mgbiker.20m.com/
- bit of an old dodgy site though - make sure your virus checker is up to date...

Marcus I rode my new build into work this morning as a test as I am taking out to the Quantocks tomorrow.

You said 'the granny ring is about 1.5mm off the chainstay'. Not sure if you mean the granny ring at the crank is close to the seat post tube or that top gear on the rear cassette is close to the chain stay.

All my tolerances are fine but my rear Hope rotor is quite close to the chain stay. I was surprised at how well the final bits came together without the usual faffing. I sized the new chain OK, the front mech went in and set up perfectly with only a few tweaks, the rear mech was even easier and I had no problems when I bled the rear brakes after trimming down the hose. That's really unlike me.

The ride to work isn't much of a test ride but it does at least prove the whole thing hangs together. It seems quite quick to accelerate and feels nimble. It seems to fit me really well and on the one short nasty climb felt really capable. I suspect the frame geometry suits me more than the old bike. It also felt quite smooth, maybe it was the off road tyres on the road, maybe it was the magnesium.

True test tomorrow at the Quantocks and Cannock next Sunday.