70sSanO

SRAM makes a 12-36 and Shimano an 11-36. SRAM cassettes are Shimano compatible. SRAM 1050 and 1070 are good cassettes.

My issue is the Shimano 11-13 gap vs the SRAM 12-13 1 tooth gap. Both have 13-15 which are on the edge of acceptable, at least for me.

Plus a 52-12 high gear ratio is probably fast enough. Other than downhills, it is close to a 35mph gear on the flats.

John

ShannonM

And what wonderful derailleurs they were!

Let alone the 1st generation XTR... by no small margin the most beautiful components that Shimano has ever made.

--Shannon

reburns

6500.

Steve_sr

So this proposal looks like it just converts the road crank to a MTB crank. This sounds like a viable solution as long as I can find a 24 and 46 tooth ring for the front. Does Shimano have the 24 and 46 rings still available? How would I find the part numbers? Any other quality alternatives?

For all of my local rides I basically use the 39 as a 1X and very seldom the 52 or 30. It is only on tours or up in the mountains that I would need lower gearing. At my age I am not "racing" down hills so rarely need the 52.

Steve_sr

This was my original thought as a temporary change only on hilly tours.

I think that I may already have a 9-speed 11-34 in the parts archive.

So If I leave the front as-is and put a 11-34 or 12-36 cassette I'll need a RD with a 45-46 capacity which puts it into MTB territory for sure.


This says that the cog spacing is equivalent between 8-9-10 speed. What ultimately determines compatibility is the parallelogram travel being sufficient to cover the number of cogs on the cassette.

Kontact 

No. You need a 10 speed cassette with your 10 speed shifter. 10 speed shifters move the derailleur the right amount of distance for 10 speed cassette spacing and won't shift anything but 10 speed cassettes correctly. 8 and 9 speed cassettes have more space between cogs.

ShannonM

More of an old-style touring triple than an MTB crank, by my lights, but yeah, kinda.

I don't know if Shimano makes a 46Tx130mm chainring, but lots of other companies do. The Suginos are even ramped and pinned, although they're twice as expensive as the non-ramped ones. Even plain chainrings should shift pretty well over a 7 tooth gap, but it's probably worth the extra 30 bucks on an STI bike. Front indexing needs all the help it can get. The granny can be the cheapest one you can get, they don't need any shift aids, and most don't have any. There's even a school of thought that says that your granny ring should be steel, because the smaller the ring, the faster it wears, and, being small, the weight penalty is negligible. That's probably overkill for a recreational road bike.

--Shannon

Steve_sr

Correct. I was thinking RD compatibility and incorrectly included shifters and cassettes as well.

Steve_sr

I just looked at my 6603 crank and there may be another issue. The big ring is integrated into the crank arm. I am also not sure if it is offset left or right. It also looks like the bolt attachment area is thicker than the ring. While the inner ring can be easily changed the outer one is not looking like an easy swap. Am I missing something? It looks like Shimano intended it this way to make it difficult or impossible to modify.

I also have a 9-speed XTR 952 crankset on my loaded touring bike and it is similar in design to the 6603 but definitely non-symmetrical and is offset left-right.

Here is a photo of the 6603 crank arm.

Kontact 

I don't know what you mean by "integrated into crank arm". That's a normal chainring held on with 5 bolts.

70sSanO

Maybe it’s an FC-6703?

John

Steve_sr

I was referring to the square joint where the ring meets the crank arm. I don't believe that generic rings have that.

Steve_sr

No, it is a 6603. I don't believe that Shimano offered a triple in the 6700 series. At least the CN-6700 chain doesn't support a triple

Steve_sr

Here is an interesting tidbit that popped up on a Ebay search...

https://www.ebay.com/itm/305344946968

A dura-ace 46T outer ring! Unfortunately, It doesn't appear to go with the mentioned FC-7800 as all of those I see are the standard 53-39 doubles. Anyone recognize this ring? Too bad it is on the other side of the pond.

bocobiking

This rear derailleur works well with shimano 10speed setups, and you can use it with a 34tooth cog. I've done it.

Kontact 

I don't see anything but the standard way chainrings fit to crankarms. Those rings would work with any 130 BCD rings and vice versa.

That 46T chainring is designed to mount on a FC-7800 crankset, and was sold as an accessory rather than packaged as a crankset. So it is a replacement for the 53T the crankset came with or for a crank that came without rings. It will mount on your crank. So will many aftermarket rings:





I was a shop mechanic and service manager for a very long time. I'm speaking from a lot of experience.

Bill Kapaun

https://www.paul-lange.de/de/service...FC/FC-6603.PDF

Carbonfiberboy 

Leave the big ring, Absolutely no reason to mess with that. You should have a 39T middle ring, good. Go with a 26T granny ring. Try that on a hill before you change out the cassette. Ignore the specific recs for chain wrap, etc. I've run a 53-39-26 front and a 11-40 cassette on our tandem for many years, no problem. Only an idiot would use small-small. We should presume you are not an idiot. I had to use the MTB RD and a Wolf Tooth to use that 40T cassette, but it all works fine. On my single my low is 30-26 on a 9-speed triple rig. That's been good for long pass climbs for a few years. I'm 78, no great athlete, just ride a lot. If you need a Wolf Tooth to run a bigger cassette, it just lowers your RD pulley, so you have to mess with chain length, but no big deal. Works fine. But I'll bet you'll like the 26T granny. It's cheap fix.

On my tandem and single, I only use the granny on the 4 largest cogs and don't use the big ring on the three largest cogs. The middle ring can run the whole cassette. On my single, I can go big-big though that's a pilot error. On the tandem I can't go big-big, but I have a Shimano Flight Deck - I can't see the cassette at all. You wouldn't need one on a single.

Camilo

If you need more chain wrap and biggest sprocket capacity, find a Shimano 8 or 9 speed mountain bike derailleur that will handle the 34 or 36t 10 speed cassette you're looking for. It will work perfectly with your 6600 shifters. It's a simple swap: install the new 8 or 9 speed derailleur and 10 speed cassette, new (longer) chain cut to proper length, adjust derailleur and shifting.

I've done it several times - MTB 8 or 9 speed RD (Deore, XT, etc.) with 9 and 10 speed road shifters - cassette matching the shifters, not the derailleur. 10 speed derailleur won't work.

I've always just found good used Deore, XT, etc. derailleurs on EBay or the sales forums on this site. I happen to have a brand new 9 speed XT derailleur I found at a local bike swap I'm "keeping in reserve"

70sSanO

I agree not to mess with the big or middle chainring, or try and mate an XTR crank to this bike.

Your initial issue was lower gearing, so you should stick with that. You only have 3 considerations…

1. Getting a 9 speed MTB rear derailleur and chain to run with your 10 speed shifters.

2. Getting an 11/12 to 34/36 10 speed cassette.

3. Either run your current 30t inner chainring, or go to a 26t or 28t. This doesn’t need to happen right away. It is not going to impact your chain length.

Yes you might have a chain wrap/capacity issue, but who cares. Don’t use the small-small or the small-2nd, or wherever the RD folds back on itself.

When I went to a 28t ring and 36t cog I couldn’t use the small-small, so I don’t. Being a triple it is a pretty severe angle anyway.

John

Duragrouch

I can only think that you are referring to the "ledge/shoulder" that the rings fit around, quite standard; That is both for a visually "smooth" outer and inner surface once assembled, and to center the rings rather than only rely on the bolts (auto analogy: "hub piloted" versus "lug piloted"). My 50/34 double, available with steel or aluminum chainrings, I have steel (thinner rings inboard of the teeth), the ledges are designed to accommodate the thicker aluminum rings, so a bit of ledge sticks out beyond the rings on both sides. Works fine.

You've got a lot of room in the inner chainring bolt circle, to go a lot smaller. Like you have, closer gap between inner and middle, than middle and outer, just gives you more duplicate gears (though may be proper for same percent difference). The wider the gap the better, IMO (to reduce duplicate gears), provided the system will accommodate that. By the way, what you currently have is the opposite of "half-step plus granny".

Seeing pictures posted of that crank, that may be the last great Shimano crank, one that I would buy. I don't like the assym 4-bolt cranks, both aesthetics, and construction.

Kontact 

How is he going to use a 26T when the front derailleur only has a 22T capacity? 53 - 26 = 27

Carbonfiberboy 

I confess to having a steel 26T granny ring on the tandem. Reduces wear. I don't think they make them anymore though.

Duragrouch

I think a lot of non-road use steel, so I think still available, depending on crank standard. My aftermarket 50/34 double was supposed to come with aluminum rings, showed up with steel, I wrote polite WTF letter to amazon seller, pointing out the ad said aluminum rings. No problem, no need to get amazon involved, we'll send you aluminum rings. Took a month from China and through their Nevada distributer or customs agent, but they arrived. And they promptly changed their amazon ad to reflect the actual material. No longer sold on amazon, but same crank is on ebay, choice of steel (cheaper) or aluminum (only about $8 more if I recall). So steel is still around. I didn't want the weight of steel, but they turned out to be a lot thinner than cheap-bike steel cranks, and have held up well.

Carbonfiberboy 

Too many people go by numbers. What does that even mean? Assuming one is smart enough not to go small-small. It works fine. I have a 10 speed FD on our tandem and a 9 speed on my singles, works just fine on both. On the tandem, I call out "spin it up" before the granny to middle shift, uh, not necessary on my single. Many tourers use a 24T granny and I've heard of 22T but not seen it.