Replace 172.5mm crank with 175mm

carchie86

Hi,

I have ruined one of the crank arms on my spare road bike by cross-threading a pedal, stupid I know but it's beyond repair I'm told. Unfortunately FSA do not seem to sell single crank arms for the non-drive side and as it is my old bike that I now only use for commuting short distances (3.5 miles and the odd ride in winter) I'm reluctant to spend any more than I need to on fixing it.

I have found a second hand pair of crank arms and bottom bracket on Ebay starting at £10 that are an exact match to the existing crankset on the bike (FSA Vero). The only issue is that the existing crank arms are 172.5mm and the replacements would be 175mm. I'm 5'10" on a 56cm bike riding only short distances on that particular bike so would there be any issues in swapping the existing cranks for slightly longer ones?

Thanks, Chris

neal1984

Lower your saddle by 2.5mm and you shouldn't notice any difference. That's what a respected bike fitter suggested anyway. Are you sure someone can not fit your crank with a helicoil?

carchie86

Thanks Neal, I had heard about fitting a helicoil but to be honest it's not something I'd considered too much as it sounded like wouldn't be particularly cheap. Is it something my LBS shop would do and have you any ideas on the cost of doing it?

If I did go with a 175mm crank then I could easily afford to drop my saddle 2.5mm so that option would be fine as well and may prove reasonably cost effective if I can get the crank cheaply on ebay.

Matthewfalle

No need to drop saddle at all.

2.5mm is nothing on the crank - unless you are Hoy you won't notice at all.

Take off old cranks, set fire to them, fit new cranks.

Bozman

Folk will tell you to lower your saddle and I probably would too but If you buy a brand new pair of shorts do you lower your saddle? I'd guess that the padding would be at least a couple of mm thicker than an old pair.

rolf_f

carchie86 wrote:

Thanks Neal, I had heard about fitting a helicoil but to be honest it's not something I'd considered too much as it sounded like wouldn't be particularly cheap. Is it something my LBS shop would do and have you any ideas on the cost of doing it?

Do a search on here and you may find a price. Should be quick and cheap and effective though.

neal1984

I've never had it done myself but I wouldn't expect it to be expensive. £10 max IMO.

A good LBS should be able to help.

markhewitt1978

Your leg will extend more on the downstroke and come up more on the upstroke - obviously! For most this won't be an issue but if you're already marginal on fit it's something to consider.

Matthewfalle

Helicoil will work fine and be dirt cheap, no need to mess about it with changing seat heights.