GT Zum 4.0 crank change choice??

staggera99y

Hi all,

Very new here so please be gentle, here is a link to the bike
http://www.bikepedia.com/QuickBike/Bike ... jTDo2S9Kc3
Since owning it, 3 months I want to change some worn components.
Brakes from tektro to deore XT v brakes, tyres from 1.25 tioga to 2.0 Conti race kings, now I'm wanting to change the the crank due to 8 worn teeth on large crank.
I've noticed it's a square tapered crank so am I right in saying I need another square crank unless I changed bottom bracket?
If so how would I know what BB I need without removing old first?


Many thanks.

The Rookie

You can only fit square taper cranks to your current BB or change the lot.

The BB is square taper, 68mm and you can measure the length with the cranks off or go to the crank tech docs to see what width it should be.

Are you sure the teeth are worn and not shaped for shifting - it's a common mistake!

staggera99y

The Rookie wrote:

You can only fit square taper cranks to your current BB or change the lot.

The BB is square taper, 68mm and you can measure the length with the cranks off or go to the crank tech docs to see what width it should be.

Are you sure the teeth are worn and not shaped for shifting - it's a common mistake!

Now that has me thinking!! Shaped for shifting....hmmm, I presume when you shift and the front mech moves it has to come off the large crank somehow, that's best advice ever!!
Thank you.

Even though that maybe the case I have seen a rather nice Deore LX square taper crank with 3 chain rings 22/32/44T and arms for £55, if I went for this to my already installed BB it will be straightforward I guess with no messing with gear line up etc...

Many thanks

nicklouse

yes the teeth of the rings is all varied to allow for smoother shifting.

it might be it might not be as you need to know what length axle the new cranks need if the same then you are ok but spending more money than needed.

staggera99y

Well this is the crank etc...
http://bit.ly/1gkmH7x
I guess it's the correct part ( hope it's ok to link fleabay)
It's also about personalising the bike, it's 2nd hand in great condition, running 1.25 tyres but now changed to Conti race kings 2.0, tektro v brakes changed to deore XT v-brakes, so I did think a crank change and maybe the bb also.

Thanks

The Rookie

Go to the shimano techdocs site (google it) for that crank and it will tell you want width axle it needs, do the same for the current Suntour cranks and if they say the same, then you can use your BB.

staggera99y

Well I went to the site you suggest, I typed in FCC M570 and no info, 571 and a 470 but not a 570!!!
Also my suntour xct 252 no such luck either!!

Hmmmm......

staggera99y

Hi again,
I received a message from suntour today stating my BB is 110mm in length and either the 68mm or 73mm shell width depending on frame.
As I'm looking to change the crank can someone point me In the right direction please,
I'm looking at Shimano 3 chainring to suit 24 speed to suit the above dimensions, can someone pls link to some suitable cranksets please.
Oh my pocket is a little shallow so in all it needs to be under £80.

Many thanks, I look forward to suggestions.

Darrell

cooldad

Just get a Shimano Hollowtech II and have the BB shell faced, probably about £60 all in, excellent crankset and no hassles with BBs in future. Find a 9 speed one.

staggera99y

cooldad wrote:

Just get a Shimano Hollowtech II and have the BB shell faced, probably about £60 all in, excellent crankset and no hassles with BBs in future. Find a 9 speed one.

Please accept my apologies for not being up to speed....but have the bottom bracket "shell faced?"
A new one or the old one?

Edit: had a google on shell faced, don't understand entirely but if I were to get the HTII would it be a splined crank arms an would my local halfords store be able to shell face it as you say?

If not I will buy an appropriate bb and crankset.

Thanks

The Rookie

I wouldn't get the shell faced at Halfords, use a proper bike shop.

staggera99y

The Rookie wrote:

I wouldn't get the shell faced at Halfords, use a proper bike shop.

Ok thanks, I will go to a local bicycle shop instead.
So if I get the crank as suggested HT II They can mate it to my bb or to a new bb, I'm still none the wiser tbh

Darrell

cooldad

HTII cranks come with a BB, it's in the box.

staggera99y

cooldad wrote:

HTII cranks come with a BB, it's in the box.

Right I now think I'm there!!!
Two piece crank with bottom bracket, sold as a set, so I would then take that to my lbs and get them to fit it.
I will pop there tomorrow to get advice.

Thanks

cooldad

Yep.

staggera99y

Hi all, I rode to lbs this morn, parted with £100 of hard earned cash, 45mins later my bike came out fitted with a Shimano HT II with bottom bracket, oh and cleaned.
A touch on the expensive side but labour wasn't cheap, overall I'm very pleased with the parts and the 6mile tow path ride home.

Shame no iPhone app to load pics quickly.

Cheers all