74mm BCD inner ring on SilVio 2.0
- Thread starter iow
- Start date
Andrei Petrov
Member
6603 crankset on 6703 bottom bracket
Are the difficulties with the 6603 all due to its bottom bracket design? Would the 6603 chain set (and 24t 74 BCD granny ring) fit on the 6703 bb?
Are the difficulties with the 6603 all due to its bottom bracket design? Would the 6603 chain set (and 24t 74 BCD granny ring) fit on the 6703 bb?
the 6603 and 6703 bb's are
the 6603 and 6703 bb's are the same (ie. hollowtech II).
it's the smaller bolt circle diameter (74mm) of the granny ring on the 6603 crankset which makes fitting difficult, but will allow you to run a 24t ring.
the larger BCD (92mm) of the 6703 crankset means it will fit (with minor modification of the granny ring), but the smallest ring you can fit on 92mm BCD is 30T
the 6603 and 6703 bb's are the same (ie. hollowtech II).
it's the smaller bolt circle diameter (74mm) of the granny ring on the 6603 crankset which makes fitting difficult, but will allow you to run a 24t ring.
the larger BCD (92mm) of the 6703 crankset means it will fit (with minor modification of the granny ring), but the smallest ring you can fit on 92mm BCD is 30T
Andrei Petrov
Member
relieving the clamps
If the chainstay ring clamps were in fact 'relieved' (does this mean filed off?), would the spacers still be required, and would the chainline issue remain? If I understand your measurements correctly, the clamp width would need to be reduced by 3.5mm where the bolt is - is this realistic, or would this compromise the clamp in your estimation?
If the chainstay ring clamps were in fact 'relieved' (does this mean filed off?), would the spacers still be required, and would the chainline issue remain? If I understand your measurements correctly, the clamp width would need to be reduced by 3.5mm where the bolt is - is this realistic, or would this compromise the clamp in your estimation?
Interesting - particularly
Interesting - particularly that the Q ring clears without grinding. Triple cranksets are rapidly going the way of the dinosaur it seems, so stock up I suppose! ;-)
I do wonder - are you close to stall speed with that low of a granny? When I rode my older highracers, I tried super low gearing like that and found that hills for me to actually stay upright speed wise were too steep to really be riding anyway with traffic. I have my trike geared really low - but it doesn't wander all over the road when going super super slow.
Robert
Interesting - particularly that the Q ring clears without grinding. Triple cranksets are rapidly going the way of the dinosaur it seems, so stock up I suppose! ;-)
I do wonder - are you close to stall speed with that low of a granny? When I rode my older highracers, I tried super low gearing like that and found that hills for me to actually stay upright speed wise were too steep to really be riding anyway with traffic. I have my trike geared really low - but it doesn't wander all over the road when going super super slow.
Robert
Charles.Plager
Recumbent Quant
I can ride my Cruzbikes below
I can ride my Cruzbikes below 3 mph without stalling. Both of mine go down to below 17" and I'd go lower if I could do it easily without giving up the high end (~ 106").
I'm annoyed that triples seem to be going out of fashion. Oh well...
I can ride my Cruzbikes below 3 mph without stalling. Both of mine go down to below 17" and I'd go lower if I could do it easily without giving up the high end (~ 106").
I'm annoyed that triples seem to be going out of fashion. Oh well...
andrei - no, there is not
andrei - no, there is not enough material in the clamps to reduce the outside width by 3.5mm. i think you
would be lucky to gain even 1.0mm.
rose city - the lowest gear on my S2.0 is 27t x 27t (27 gear inches) which is approx. 5.5 mph @ 70 cadence. no problems with balance at this speed as long as i can maintain traction.
andrei - no, there is not enough material in the clamps to reduce the outside width by 3.5mm. i think you
would be lucky to gain even 1.0mm.
rose city - the lowest gear on my S2.0 is 27t x 27t (27 gear inches) which is approx. 5.5 mph @ 70 cadence. no problems with balance at this speed as long as i can maintain traction.
timt
Member
some 92 BCD pics
I just finished putting my Ultegra 6703 92 BCD triple on my Silvio. below are before and after pics of the modification to the sprocket.
The first picture is the crank as received. The tabs on the granny gear interfere with the bottom bracket clamp, preventing proper installation (and function) of the crank.
Note the little tab (circled) and arrow are lined up. Put them back together this way.
alt="tabs in place (before)"
The second picture is an "after" shot. There's about 1.5-2mm clearance between the shortened tab and the BB clamp and the crank is fully seated against the BB.
I cut the tabs off with a fine blade on a jigsaw. Then I cleaned it up with a sanding roll on the dremel.
alt="trimmed tab"
If you are happy with a 30 tooth granny, this is pretty easy. The downside is you have to buy an ultegra 6703 crank instead of a cheaper 105, tiagra, etc. I stress 6703 because the older 6603 is 74 BCD.
If you want smaller than 30 teeth, get a 74 BCD crank, and follow IOW's directions for trimming and offsetting in the posts above.
I just finished putting my Ultegra 6703 92 BCD triple on my Silvio. below are before and after pics of the modification to the sprocket.
The first picture is the crank as received. The tabs on the granny gear interfere with the bottom bracket clamp, preventing proper installation (and function) of the crank.
Note the little tab (circled) and arrow are lined up. Put them back together this way.
alt="tabs in place (before)"
The second picture is an "after" shot. There's about 1.5-2mm clearance between the shortened tab and the BB clamp and the crank is fully seated against the BB.
I cut the tabs off with a fine blade on a jigsaw. Then I cleaned it up with a sanding roll on the dremel.
alt="trimmed tab"
If you are happy with a 30 tooth granny, this is pretty easy. The downside is you have to buy an ultegra 6703 crank instead of a cheaper 105, tiagra, etc. I stress 6703 because the older 6603 is 74 BCD.
If you want smaller than 30 teeth, get a 74 BCD crank, and follow IOW's directions for trimming and offsetting in the posts above.
