Bingod

I have a Shimano FC-3503 with 175mm crank arms and want a new crank with shorter arms. Not much available but I found a 5703 at 170mm. I am aware that if i use this crank i will probably need to use spacers to maintain the correct chainring spacing. But I'm curious, will my old 9 speed rings fit the new crank and if so would I still need spacers? I would consider a 3030 crank but I use a 26T inner ring and I don't believe I can find one for this newer model. Thanks

HillRider

I'm pretty sure the FC-3503 has 130/74mm bolt circles and it's chainrings should be a direct fit onto an FC-5703 crank arm. No spacers should be needed. BTW, treasure that 5703 crank. They are hard to find and are the last Shimano road triple that has the separate 74mm granny bolt circle.

icemilkcoffee 

Tiagra 4503 is also 9 speed:
https://www.ebay.com/itm/265062537308

Bingod

Thanks - a good suggestion. The 105 i found is considerably cheaper and new. Im going to buy it now - hope the sale works out

Bingod

Same BCDs. good to know about the spacers as I just recently bought new rings for Sora and will make the swap a lot easier.

icemilkcoffee 

Another choice would be the Sora R3030:
https://www.ebay.com/itm/384031455531
It's also 9 speed. The 10 speed 5703 crankset would probably work, but triple cranksets being super touchy to dial in correctly, I would stick to all 9 speed components to minimize headaches.

Bingod

Rats! looks like a scam. I'll keep looking. (Edit: The 105, that is)

Bingod

I hear you. R-3030 would be first choice but i don't believe i can use a 26T inner chainring

Bingod

Would a 5503 crank work? If I can use my chainrings then this could be a cheap, albeit silver, alternative, that looks almost identical to a 3503, plus I can keep my old octalink BB. The few I've seen look pretty trashed though

icemilkcoffee 

Yes. 5503 would definitely work too. That one is also 9 speed. Same with 4403, 6503.
However there is no guarantee that the octalink BB would work because Shimano had changed Octalink like 2 or 3 times.

HillRider

AFAIK, there were only two different Octalink designs, V1 for most road cranks and V2 for most MTB cranks. V1 was made in 109.5mm for doubles and 118.5mm for triples. 5503, 4503, 6503, etc. all used V1.

KCT1986

The FC-5503 uses a 118.5mm Octalink V1 BB. The only V1's in this size are BB-7703, BB-5500, BB-6500. BB-M95x are also V1 but not in the 118.5 size.

All other Octalink BB (BB-ESxx) are V2 and have a different spline pattern.

KCT1986

The FC-4503 has the spindle attached to the crankarm and uses a external BB.

The Tiagra with a Octalink BB is in the 4400 series. More specifically the second versions only, FC-4402 and FC-4404. These uses the V2 BB (BB-ESxx) not the V1's.

The Sora 3300 series also uses the V2 Octalink.

Bingod

Job done. I found a new 5703 crank without rings (I will treasure it) and a new 5800 left crank arm, plus RS-500 BB. All went together without a hitch and it works great.