Saracen lovers, at question for you...

[unocogero]

Hi Saracen experts,

Could anyone give me a rough idea of the best spindle length for a mid 90' Saracen Backtrax. It's blue if that helps anyone date the neast.

I'm building it up for a friend so I don't want to waist his money buying the wrong BB.

Any other info on the Backtrax would be useful.

Cheers

 

[drystonepaul]

Depends what cranks you have in mind. Some Saracens do have 73mm BB shells though.
What have you got planned Mat?

 

[Dead Rats]

I've recently been fiddling with a '95 Backtrax (it's now single speed, with v-brakes as the old cantis were buggered) and it had a 73 x 121mm cartridge BB which threaded in non drive-side first. It also had a NASTY b-bracket mounted front mech (does that explain the back to front b-bracket?) and pretty much Shimano Altus groupset throughout (except front hub which was Sachs - presumably stock?). It also had a cracked driveside crank... when I say cracked I mean snapped off completely!

Nice if heavy bike - like most low end early-mid '90s 'Rens really - and now a svelte-ish 60" geared pub bike:

 

[unocogero]

Interesting. The shell is definately 73mm and I can find replacement 122mm spindle lengths on chain reaction...

@ Deadrats: Did you use the old BB or did you replace it? Does 122mm seem right for the frame? Does the side it screw into matter then or can I just fit a standard UN54 BB?

@ Paul: Hi Paul, I've bought some old specialized cranks from Lewis1641. Will the cranks make a difference to the required spindle length?

Just as the fog was beginning to clear!

Cheers

Mat

 

[legrandefromage]

122mm is fairly wide, it all depends on the cranks you are running.

My Sahara ran a very narrow spindle length to fit low profile chainsets (M730 XT is 'old' style profile, M900 XTR is 'low' profile)

If you are using compact drive cranks, these are low profile and can sometimes require very narrow axle.

You have to look at the arm clearance for the rear stays and the ring clearance

 

[Dead Rats]

Interesting. The shell is definately 73mm and I can find replacement 122mm spindle lengths on chain reaction...

@ Deadrats: Did you use the old BB or did you replace it? Does 122mm seem right for the frame? Does the side it screw into matter then or can I just fit a standard UN54 BB?

@ Paul: Hi Paul, I've bought some old specialized cranks from Lewis1641. Will the cranks make a difference to the required spindle length?

Just as the fog was beginning to clear!

Cheers

Mat

I also suspect as lgf does that your replacement cranks will require a narrower BB... I think my 107mm would just accept a granny ring.

I however used a narrower 107mm BB purely cos I'm running a single outer ring up front on what sounds like very similar cranks to the ones you're planning to use and when I tried the old BB it placed the ring too far out for my tensioner to cope with!. The BB shell threads are completely normal - it just had the old unusual reverse BB based on, I presume, the BB mounted front mech.

There's no reason why if I was keeping the old triple crankset* I couldn't just use a standard 28.6mm band-on top-pull front mech and a standard BB such as, as you say, a UN54 in same width as before. I suspect the 121mm BB (not 122mm - it's stamped 121 - odd I know) was stock as it took a hell of an effort to get it out!

* the other reason being that it had snapped off! :shock:

 

[unocogero]

I've just whipped the cranks off my 1990 Fire Mountain and thats around the 110mm mark. The clearance looks similar on both bikes and as I'm single speeding it and can adjust where the rear cog is a good compromise might be a 113mm spindle.

Is this logical or woolly thinking?

 

[unocogero]

Thanks dead rats, I'd posted ebfore I'd seen that...so maybe 110mm would do?

 

[Dead Rats]

I've just whipped the cranks off my 1990 Fire Mountain and thats around the 110mm mark. The clearance looks similar on both bikes and as I'm single speeding it and can adjust where the rear cog is a good compromise might be a 113mm spindle.

Is this logical or woolly thinking?

you never said anything about single speed! what are you using as a tensioner?

 

[unocogero]

I'm using a Gusset Batchelor. I suppose it might be geared one day but probably not.

Your build, which looks great, is my intended end product.

I think the frame is butted as it does the ping thing and it is no way near as heavy as the Fire Mountain!