New Bike busted. Pls help with fix.

For discussions about bikes and equipment.
wertert
Posts: 1
Joined: 10 Aug 2019, 12:23pm

New Bike busted. Pls help with fix.

Postby wertert » 10 Aug 2019, 12:31pm

Hi All

Bought a new bike and used it for a couple of weeks to compute into work. It wasn't expensive but I've managed to strip the thread from the left crank arm and cross thread the right pedal. Such a donut. Pedals were only finger tightened.

It's a Marin LARKSPUR CS1 city. According to their web site I need a Shimano FC-TY301, 48/38/28T, Ring Guard 175mm ( bike is a large size )
I can't find this exact crankset anywhere ( too old ? ). I have a friend who could fit a replacement crankset if I can find something that fits.

Sorry about the noob question but any ideas what I can use instead ? There seem to be plenty of FC-TY501 sets around. Are these the same size ? TBH Only the crank arms need swapping out but again I'm not sure what I'm after. I seems simpler to just swap the whole set.

What happens if I get a different number of teeth ? i.e SHIMANO FC-M171 SQUARE TAPER 3 X 6/7/8S BIKE CRANKSET 175MM 42/34/24T

Thanks all in advance.

wert

Brucey
Posts: 34868
Joined: 4 Jan 2012, 6:25pm

Re: New Bike busted. Pls help with fix.

Postby Brucey » 10 Aug 2019, 12:38pm

any shimano square taper chainset that has the same chainline/crank length/ ring sizes ought to work, but some may use a different length bottom bracket spindle, so check carefully or just replace it anyway.

[edit; both FC-M171 and FC-M391 use a 122.5mm bottom bracket, as should FC-TY301]

cheers
-------------------------------------------------------------------------------
~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~

User avatar
squeaker
Posts: 3539
Joined: 12 Jan 2007, 11:43pm
Location: Sussex

Re: New Bike busted. Pls help with fix.

Postby squeaker » 11 Aug 2019, 12:03pm

wertert wrote:What happens if I get a different number of teeth ? i.e SHIMANO FC-M171 SQUARE TAPER 3 X 6/7/8S BIKE CRANKSET 175MM 42/34/24T

1) the gearing will be 10% (high) to 14% (low) lower
2) the chain will (probably) need shortening a little
3) the front changer will need lowering to stay within ~2mm of the large chainring (can it be lowered?) and may prove problematic - check compatibility with the relevant Shimano technical documents

PS: https://www.ebay.co.uk/itm/Shimano-FC-T ... SwHp5bYYj9
"42"

gxaustin
Posts: 480
Joined: 23 Sep 2015, 12:07pm

Re: New Bike busted. Pls help with fix.

Postby gxaustin » 14 Aug 2019, 11:50pm

Spa cycles have a good selection of square taper triple chainsets with cranks up to 175mm.
Buy the right replacement and you can use the rings from the old chainset as spares for the new one.

JohnW
Posts: 6158
Joined: 6 Jan 2007, 9:12pm
Location: Yorkshire

Re: New Bike busted. Pls help with fix.

Postby JohnW » 15 Aug 2019, 2:02pm

wertert wrote:Hi All

Bought a new bike and used it for a couple of weeks to compute into work. It wasn't expensive but I've managed to strip the thread from the left crank arm and cross thread the right pedal. Such a donut. Pedals were only finger tightened.

It's a Marin LARKSPUR CS1 city. According to their web site I need a Shimano FC-TY301, 48/38/28T, Ring Guard 175mm ( bike is a large size )
I can't find this exact crankset anywhere ( too old ? ). I have a friend who could fit a replacement crankset if I can find something that fits.

Sorry about the noob question but any ideas what I can use instead ? There seem to be plenty of FC-TY501 sets around. Are these the same size ? TBH Only the crank arms need swapping out but again I'm not sure what I'm after. I seems simpler to just swap the whole set.

What happens if I get a different number of teeth ? i.e SHIMANO FC-M171 SQUARE TAPER 3 X 6/7/8S BIKE CRANKSET 175MM 42/34/24T

Thanks all in advance.

wert


It sounds to me that the bike wasn't properly assembled to start with. Why not take it back to the bike shop?

edited for grammar and spelling!!!! jw
Last edited by JohnW on 17 Aug 2019, 11:06am, edited 1 time in total.

gregoryoftours
Posts: 999
Joined: 22 May 2011, 7:14pm

Re: New Bike busted. Pls help with fix.

Postby gregoryoftours » 17 Aug 2019, 1:18am

You could try installing the Rh pedal from the rear of the crank (tightens backwards instead of forward). Sometimes it can clean up the damaged thread enough that it's possible to then install the pedal correctly. Obviously not a good idea if there is a lot of damage to the thread as you run the risk of your pedal coming off while riding.