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General Category >> Technical >> Compact Crankset
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Message started by jayg on Feb 22^nd, 2011, 4:59pm

Title: Compact Crankset
Post by jayg on Feb 22^nd, 2011, 4:59pm

I have trial-installed an external bearing bottom bracket and 9-speed, triple crankset on my Baron, and found that the small chain ring is not accessible, because derailleur cage movement is blocked by the crank boom. I now want to try a compact crankset with external bearing bottom bracket, however, the desirable cranksets I have found on E-Bay are all 10-speeds. Are there any members that have successfully used a 9-speed chain with a 10-speed compact crankset?

Title: Re: Compact Crankset
Post by aikigreg on Feb 22^nd, 2011, 5:30pm

I dunno, Jay, but you can, depending on the crankset, get a spacer and shift the cranks over enough to clear the boom - I did it on my baron way back when and it shifted great.

If that doesn't work I have a new ultralight 10 speed KMC chain I might trade you for a 9 speed if you have it. I may be converting my carbent to a 9 speed.

Title: Re: Compact Crankset
Post by power_bent on Feb 22^nd, 2011, 5:36pm

I dunno, Jay, but you can, depending on the crankset, get a spacer and shift the cranks over enough to clear the boom - I did it on my baron way back when and it shifted great.

Get a longer(wider) crankshft spindle....

Title: Re: Compact Crankset
Post by jayg on Feb 22^nd, 2011, 6:37pm

aikigreg wrote:

Greg, thanks for your input. I guess a triple crankset suitable for a 73 mm bottom bracket could be used in conjunction with a spacer and 68 mm bottom bracket. Part of the problem I'm having is caused by the boom almost being bottomed out (I'm short). The derailleur cage is actually contacting the boom receiver, instead of the boom. So, cage movement is even more limited. I don't plan on climbing any steep hills with the Baron, so I want to try a compact crank, instead of another triple.

I wonder if a 10-speed chain would be compatible with my Baron's 9-speed cassette? I don't have a new 9-speed chain to trade. The chain on the Baron currently has 723 miles on it.

Curious as to why you want to convert your Carbent to 9 speed? I've never been able to keep the 10-speed Ultegra bar end shifter/rear derailleur combo on my Carbent in adjustment. Wonder if a SRAM 10-speed, "Exact Shift" combo would be better?

Title: Re: Compact Crankset
Post by aikigreg on Feb 22^nd, 2011, 6:50pm

Well, what I REALLY want is for sram to make a set of long pipe shifters that are 10 speed. My wife's ans F5 came with long pipe shifters and they are a breeze to shift. Shorties just hurt my wrist. So I've been using bar end shifters on the carbent - Shimano, which are about to break at any time. I'm just generally disgusted with shimano and the way they engineer shifters to break. And I can't afford the sram XX gruppo that I want to replace it. Going back to 9 speed is a much more inexpensive way to do what I gotta do until the money comes in for the change.

Title: Re: Compact Crankset
Post by jayg on Feb 22^nd, 2011, 6:52pm

power_bent wrote:

Tom, I installed an ISIS triple crankset and heavy, 128 mm (super wide), mountain bike bottom bracket and could get the drailleur to access the small ring. I screwed up the bottom bracket when I removed it to try an external bearing bottom bracket and carbon triple crankset. Instead of buying another 128 mm bottom bracket, I want to try another external bearing bottom bracket and light compact crankset.

Title: Re: Compact Crankset
Post by jayg on Feb 22^nd, 2011, 7:02pm

aikigreg wrote:

Well, what I REALLY want is for sram to make a set of long pipe shifters that are 10 speed.

Me too.

Title: Re: Compact Crankset
Post by jayg on Feb 23^rd, 2011, 5:02pm

Rode over to Dallas Bike Works at WRL, this afternoon, and talked to one of their mechanics. He said a 9-speed chain would be compatible with a 10-speed compact crankset. He suggested use of a 10-speed front derailleur for smoother shifting. Subsequently, I pulled the trigger on a new 165 mm Ultegra compact crankset w/bottom bracket for just $130 on E-Bay. Hope it works on the Baron.

Title: Re: Compact Crankset
Post by jayg on Feb 27^th, 2011, 6:13pm

Received my new Ultegra compact crankset yesterday afternoon and installed it on the Baron. The 9-speed Shimano 105 triple front derailleur and 9-speed chain on the bike are compatible with the new 10-speed, 34/50, double crankset. Took the Baron for a 37 mile test ride this afternoon. Only one slight problem - when the chain is on the big ring, it makes light contact with the axle screw for one of the return idlers. No big deal. I'll install a short chain tube. The compact crankset is fine for riding at WRL, but I wouldn't want to try to ride Muenster without packing some hill walking shoes in my bag. :)