Making a Super Compact Chainset?

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PpPete

Legendary Member
Location
Chandler's Ford
Get out and ride?
what ?
and deprive us of of further doses of all this accumulated wisdom ?

Shame on you MacB :biggrin:

Seriously though, did u sort that question of tyre clearances in the OP? I was rather struck that you were putting a lot of ££ into a super whizzy Ti Frame... and then giving yourself problems by asking it to take 44 mm tyres that will likely weigh more than any weight saving from using Ti in the frame. Dont get me wrong, not a criticsm, I know you like your big tyres, (in the same way that I put stupidly skinny tyres on an old steel touring frame) - just wondered how you resolved it ?
 
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MacB

MacB

Lover of things that come in 3's
Well Vaya build back on hold for a couple of days, thought I'd been really whizzy when I stripped the Pompetamine. Kept bars, stem cables and disc brake calipers all hooked up together. Yes it slotted on to the Vaya very neatly but...there's always a but....the Goodridge cable outers were trimmed to fit the Pomp and the Vaya is a rather larger frame. It's close, could set it up and ride it as long as I didn't turn any corners :biggrin: so just ordered some more Goodridge outer.

Pete, the tyre clearances, yeah I've had a bit of an overall change in my intended use/design for the Ti frame, signed off on it today. I'd gotten too hooked up on versatility and multiple use, same as with the Crosscheck, hence why that's being sold off. I've reverted back to the original setup of the Dawes as a pub/shop/backup commuter and put some better parts on it. That had been the intended role for the Surly but it's a bit expensive to just leave anywhere. But I loved the ride and clearances on the Surly and the Vaya ticked the boxes as a replacement. It differs in longer chainstays, compact geometry, longer head tube, vertical dropouts hence the EBB and disc mounts. The rear disc mount is chainstay orientated so no interference with rack/guards. But Salsa and Surly are both owned by QBP the huge bike company, so same frame material, build, etc. So the Vaya is good as a commuter but it also has touring pedigree as well with front rack mounts etc, I've gained in that respect if I ever want to tour. Both the Vaya and the Dawes can take my Winter studded tyres and both have rack, guards etc.

Originally I'd been thinking of the Ti frame as a commuter/backup weekend bike and looking towards a new disc brake weekend bike in carbon, like the Volagi. But a bit of common sense struck and I realised I was going to end up with more bikes than my stable required, I still believe in 3 being a good number, with 4 only happening if I want to do proper MTBing. A leave anywhere bike that can cope with backup commuting duties, a dedicated commuter that could cope with weekend duties and a weekend that could cope with commuting. If I'd ploughed ahead I would have ended up with the Surly as the leave anywhere(I don't think so somehow), the Vaya as a sort of floater, the Ti as a commuter and the Volagi as a weekend. I admit I was drawn to the idea of a Ti commuter, ie weather proof. But some further thought led me to recognise that it was overkill for purpose and a steel frame commuter would see out my working life no problem.

That's a long way to say the design concept of the Ti changed to more road/audax but still with some of my little quirks. The 44mm tyre clearance was just to match the Windwood Muddy Cross disc forks, I have an orderly mind. Now we've agreed that 44mm isn't a must have and tyre clearance will be maximised but without resorting to S bend chainstays. This will mean that I'll certainly get clearance up to 35mm, so can run studded tyres if desired, and that's good enough. I also decided to go with dropout/seatstay disc tabs rather than chainstay, if I have to use a rack then I'll get a disc specific one. For the sort of rides this will be for then the most I'd take would be a rackpack, I have an Arkel Tailrider. Coincidentally Arkel have brought out a new 'Randonneur' rack which is seatpost/saddle rail mounted:-
http://www.arkel-od.com/us/arkel-randonneur-rack.html
I'm rather taken with this as an idea, QR mounting, quick and easy and allegedly very stable due to the 3 supporting points, or certainly in comparison to other beam racks. I'll know better after the night rides get going again as TimO has bought one and I'll get to see it in action.

The final design of the Ti frame bears a remarkable resemblance to a Spesh Roubaix, a bike I've both admired and test ridden, and comes in between their 56 and 58 sizing. Similar geometry, I'm sticking with a 200mm head tube, I've lengthened the chainstays to 435mm but the overall wheelbase is only about 1027mm and the trail comes in at 61mm with 32mm tyres. This is 4-5mm less trail than all my other bikes have been so should give me a more agile ride without getting into twitchy country. The effective TT is 570mm and, coupled with a 120mm stem, should give me a saddle nose to bars reach of about 550mm(with saddle in centre of rails and an inline seatpost), which is spot on compared to all my other setups. The saddle setback from BB is bang in the middle of my setback range at 74.5mm so this allows for a bit of tweaking with the saddle being in the middle of the rails. Compact geometry as well but not crazy sloping, just midrange.

I've paid the deposit so it's all systems go(Justin at Burls has been very patient with me), can you tell I'm excited? Jane and the boys have no interest in any of this, their eyes just glaze over if I start talking about it :blush: But you can expect further lengthy deliberations and procrastination as I try to decide on the precise build spec for the Ti frame. The only definites so far are the frame, forks and a Thomson Elite inline seatpost, you can imagine how bad I'm going to get choosing the rest :ohmy:
 

PpPete

Legendary Member
Location
Chandler's Ford
I've paid the deposit so it's all systems go(Justin at Burls has been very patient with me), can you tell I'm excited? Jane and the boys have no interest in any of this, their eyes just glaze over if I start talking about it :blush: But you can expect further lengthy deliberations and procrastination as I try to decide on the precise build spec for the Ti frame. The only definites so far are the frame, forks and a Thomson Elite inline seatpost, you can imagine how bad I'm going to get choosing the rest :ohmy:

Bated breath....:biggrin:
 

P.H

Über Member
without resorting to S bend chainstays.




Interesting reading and I agree three bikes is the ideal stable for road and touring. I'm puzzled by the above, do you dislike shaped chainstays? I'd have thought they were an idea way to get tyre, chainring and heel clearance. Many Ti frame builders use them and I'm not aware of anyone having a problem.
 
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MacB

MacB

Lover of things that come in 3's
Interesting reading and I agree three bikes is the ideal stable for road and touring. I'm puzzled by the above, do you dislike shaped chainstays? I'd have thought they were an idea way to get tyre, chainring and heel clearance. Many Ti frame builders use them and I'm not aware of anyone having a problem.

that versatility bit again, I was led to believe that the use of s-bend chainstays could limit choice of chainset due to chainring clearances. If that's not the case then I'd be interested to know.
 

P.H

Über Member
that versatility bit again, I was led to believe that the use of s-bend chainstays could limit choice of chainset due to chainring clearances. If that's not the case then I'd be interested to know.
I'm not sure, there's so many variables. I've seen some MTBs with very wide tyres and short chainstays, that don't seem to have a problem, though they're running the appropriate chainset. The only bike I have with shaped chainstays runs a single ring and was specified for 35m tyres so it's hard to work out from there. In the end you have to trust the framebuilder you're chosen.
 
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MacB

MacB

Lover of things that come in 3's
I'm not sure, there's so many variables. I've seen some MTBs with very wide tyres and short chainstays, that don't seem to have a problem, though they're running the appropriate chainset. The only bike I have with shaped chainstays runs a single ring and was specified for 35m tyres so it's hard to work out from there. In the end you have to trust the framebuilder you're chosen.

:biggrin: Very diplomatically put, too late to change now the trigger has been pulled, you are of course free to contribute on my component procrastination. I think this thread idea may now be dead in the water as I'm probably going to go triple in the end :whistle:
 
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MacB

MacB

Lover of things that come in 3's
Have you thought of a Stronglight Oxale two (29/44) from Spa Cycles for £85, available elsewhere too. You'd need a 108 Isis BB.

See http://www.spacycles...lid=m2b0s109p43

That was one of the early chainsets that got me thinking on the whole idea. My doubts were that Spa only had the 170mm cranks and I wanted 175 and I read some poor reviews of the ISIS crank fitting. A quick trip to Stronglight shows they no longer do the Oxale Two but they do now have the Meister STK X2:-

http://www.stronglight.com/stronglight/page.php?nom=produit&keyProd=Meister_X2

still the 9 speed 44/29 or 42/29, the 42/29 with a 9 speed 11-32 cassette makes quite a nice spread. I may have to investigate this further, thanks!!!!! :biggrin:
 
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MacB

MacB

Lover of things that come in 3's
well I have a Tiagra triple chainset, 30/42/53 - I've replaced the 30 with a 24t and will need to replace the other two(I got a good deal on this), so I was messing about with this idea again. As, at least for initial setup, I'm cost saving now, I'm sticking with the 9 speed bar end shifters. I'm focusing my dosh on frame, headset, forks and wheelset.

First thought - put a 40t middle, bash outer and run 40/24 with a road double FD, or maybe 42t(as they seem more readily available) and risk the 18t rather than 16t variance. Maybe trial it with the existing 42t ring and an old cassette and chain to see how it works.

The middle ring has a 45mm chainline using a 113mm BB so - based on RecordAces cassette info - that should put that ring in prime spot to hit whole of cassette. The inner ring only needs to hit the first largest 4/5 so not concerned about little/little working. Or should I go to a 115mm BB to get the chainset out a tiny bit?

As I'm using the non indexed barend front shifter, STI compatibility no longer an issue but now trying to work out which FD and will I be able to clamp it low enough on ST to work? Also if I use a road double will the arc of the FD be incompatible with the arc of a 40/42t chainring? Again I have the option of getting an old part from LBS and maybe having a go at reshaping if need be.

Has anyone else done anything like this, I am relying on the fact I can fall back to just running it as a 1x9 setup if need be.
 
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MacB

MacB

Lover of things that come in 3's
Yep, it all worked out very well, the 40/24 shifted fine with a road double FD and the rear was comfortable on all 9 cogs from the 40t and 7 from the 24t.
 
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