32t cassette

fattywilliams

Doing velothon Wales at start of next month and could do with a bit lower gearing if it possible. Have ultegra 6870 Di2 short cage rear derailleur and a 52/36 crankset. Don't really wanna change cranks as more expensive

But can I put a 32t cassette on clearance looks like it will be okay just worried about changing into a big big combination by accident? I guess if chain long enough it will work right ?

photonic69

Seems not:

http://bike.shimano.com/content/sac-bik ... 70-ss.html

fattywilliams

Thanks for reply I'm aware officially it can't be done however I've ran a 32t on a sram rear mech only designed to take 28 no problem and have seen quite a few others do it however this was with a 50 big ring not 52 and specificly not Di2 which I don't wanna bust up

I'm fairly confident the 32 wouldn't hit rear mech and if it did I could use a road link to increase clearance just little cautious about the chain length issues

I.e if I increase chain to cope with a accidental 52/32 combo then will it then be too slack in normal gears or say 36/13

Alex99

fattywilliams wrote:

Thanks for reply I'm aware officially it can't be done however I've ran a 32t on a sram rear mech only designed to take 28 no problem and have seen quite a few others do it however this was with a 50 big ring not 52 and specificly not Di2 which I don't wanna bust up

I'm fairly confident the 32 wouldn't hit rear mech and if it did I could use a road link to increase clearance just little cautious about the chain length issues

I.e if I increase chain to cope with a accidental 52/32 combo then will it then be too slack in normal gears or say 36/13

You seem to be well aware of the issues and potential show stoppers. As you rightly point out, it is often possible to go beyond the official limits with these things if you're careful. It's probably down to you and how 'gear aware' you are.

timothyw

Yeah. I imagine I'd be OK, as I never run in small chainring - small cassette combos - that's the main risk doing what you're suggesting (assuming you can adjust the b screw sufficiently to clear the cassette) - so if you know that you are good at getting back into the big ring then it shouldn't be a problem.

I don't know that I'd want to risk it where expensive di2 derailleurs (and a presumably nice bike) are at risk however.

Do you already have a 11-28 cassette?

Better bet might be finding a friend with a 50-34 chainset you can borrow - five minute job to swap them over.

Incidentally, can't see any reason why a 52 tooth big ring would make any difference to whether this will work or not - 52-36 is the same gap as 50-34

weezyswiss

I run Ultegra Di2 on an 11-32 rear, but I use the long cage. Hills not my thing hence the 32 and useful when in the hills of Snowdonia or Yorkshire (at least for me)

I do find that the chain can "flap" a little but I use that as a gauge that I need to change it as it has stretched too much

rick_chasey

fattywilliams wrote:

Doing velothon Wales at start of next month and could do with a bit lower gearing if it possible. Have ultegra 6870 Di2 short cage rear derailleur and a 52/36 crankset. Don't really wanna change cranks as more expensive

But can I put a 32t cassette on clearance looks like it will be okay just worried about changing into a big big combination by accident? I guess if chain long enough it will work right ?

This annecdote may be of use, it may not.


I ran 53x39 with 12-30 and every gear selection worked except for 39x12 because the derailleur couldn't get any slacker, so I just avoided that gear ratio, which wasn't all that difficult.

But that was the limit.

Bobbinogs

WeezySwiss wrote:

I run Ultegra Di2 on an 11-32 rear, but I use the long cage. Hills not my thing hence the 32 and useful when in the hills of Snowdonia or Yorkshire (at least for me)

I do find that the chain can "flap" a little but I use that as a gauge that I need to change it as it has stretched too much

You really need to find a better way to measure chain stretch!

janwal

Roadlink website states it can only be used with a medium cage rear derailleur.

fattywilliams

janwal wrote:

Roadlink website states it can only be used with a medium cage rear derailleur.

Believe that only applies if you want to go proper mountain bike gearing IE 36 or 40 cassette all it essentially does increase clearance so would definitely work I've seen it work and as I say I think it would clear anyway. Just losing my bottle a bit cuz I don't wanna reck my Di2

It's like shimano brakes until recently ultegra and dura ace brakes officially won't work with a tyre over 25c but how many bike you seen with 28+

I'm no expert why I asked by that's my opinion

964cup

You can fit a UCB speedcage to the RD to increase chainwrap capacity. I fitted one to my DA9070 RD and run an 11-32 routinely. It's a 10 minute job to fit.

fattywilliams

964Cup wrote:

You can fit a UCB spveedcage to the RD to increase chainwrap capacity. I fitted one to my DA9070 RD and run an 11-32 routinely. It's a 10 minute job to fit.

Yh that's not a bad ideal although quite costly think it would work out cheaper to buy the GS mech and sell the short one on eBay that's kinda what I'm leaning to at the moment

meanredspider

Regularly seeing posts where people with so-called "Pro compacts" (52/36) need to gear-down for hilly rides. When the trend in any case is to go for shorter gearing (even amongst the pros themselves, seemingly), these "semi-compacts" seem like a retrograde step.

sh3p

if it helps and I'm a trusting kinda guy ...also doing the velothon Wales I have some ultegra 50/34 chainrings or a full chainset 172.5 you are welcome to borrow for the event...drop me a pm if is usefull to you ,we will be there on Saturday for registration and stuff (staying in local travel lodge)
cherrs Dave

fattywilliams

meanredspider wrote:

Regularly seeing posts where people with so-called "Pro compacts" (52/36) need to gear-down for hilly rides. When the trend in any case is to go for shorter gearing (even amongst the pros themselves, seemingly), these "semi-compacts" seem like a retrograde step.

Yh I think I'd probably agree speced it on the bike as I dint know anything about gearing at the time and used to grind more than spin now I wish I would of put a fully compact on although for what it's worth I do like the 52 when pushing on long decents so if I could have a 11-32 on the back and keep my 52/36 that would be ideal but I need to decide if it worth spending the money don't think I will risk doing a bodge/hack on it anymore

fattywilliams

sh3p wrote:

if it helps and I'm a trusting kinda guy ...also doing the velothon Wales I have some ultegra 50/34 chainrings or a full chainset 172.5 you are welcome to borrow for the event...drop me a pm if is usefull to you ,we will be there on Saturday for registration and stuff (staying in local travel lodge)
cherrs Dave

Thanks mate really appreciate that if it comes to I may message you nearer the time. thanks for such a kind offer mate!

sh3p

no problem a pleasure